ARRAY electronic loads - Page 1
Forum section: electronics / testgear

author: Unknown
author_rank: Unknown
timestamp: February 06, 2012, 04:03:53 pm
content: Hi, I was just wondering if anyone has had any experience with the Chinese ARRAY (rebranded?) electronic loads:http://www.array.sh/yq-3700e.htmAny info would be useful!

author: Short Circuit
author_rank: Frequent Contributor
timestamp: February 06, 2012, 04:52:30 pm
content: Readings are not very accurate, and PC control next to worthless, clumsy terminals.But overall, it's very good value for money. Offers various load modes, such as constant current, constant power, resistive.

author: olsenn
author_rank: Frequent Contributor
timestamp: February 06, 2012, 06:16:51 pm
content: I stand by the performance of my Itech (BK Precision) IT8511 DC electronic load... it is wonderfully designed and worth every penny if your work requires such a device

author: bsgd
author_rank: Regular Contributor
timestamp: February 06, 2012, 06:38:45 pm
content: I am also looking for a electronic load for my lab, but I dont wanna spend a fortune... if you guys have some nice and cheap recommendations it would be pretty nice!

author: olsenn
author_rank: Frequent Contributor
timestamp: February 06, 2012, 06:49:38 pm
content: In my opinion, NEVER CHEAP OUT! If you only need a power resistor for something in particular than that will be cheaper and more reliable than any electronic load, but if you are going to go for a professional tool like that, then you're better off paying $500 for something that will last forever, as opposed to something that either breaks down in a year, or is so pathetic in terms of features and accuracy that you'll end up buying that $500 one eventually anyways, the $150 one will end up in a closet (and never come out again) and you'll have spent $650 for something that you could have gotten for $500.That being said, if you are hell bent on spending no more than $200, then have a look on ebay; they have an assortment of cheap DC loads.

author: Unknown
author_rank: Unknown
timestamp: February 06, 2012, 07:13:38 pm
content: Thanks for the replies.Pretty much what I would expect Short Circuit, at ~£200 it is excellent value for money as you say. Have you pushed it to the higher end of its power dissipation capability? Does it feel like it will blow up?Olsenn, could you comment on the PC communications for the IT8511? It would be very useful to setup a test waveform on the PC, download it to the load and have a scope syncronized to the output of the PSU under test.Unfortunately high(er) voltage PSUs will frequently be tested, 140, 250V DC come to mind at a low current 1-10mA. The ARRAY 3710A quotes 2%+3mA accuracy in this range, so I will probably need a DMM too for current measurement if I am to have any confidence in it. From the Itech line the IT5812B can go up to 500V and the current accuracy quoted is 0.1mA (no further info is given on that figure).The (looking on ebay) BEICH CH8710B looks like it is the same hardware as the ARRAY device, with a different screen. It can do up to 360V. There is also the M9712B that goes to 500V and seems similar to the Itech/BK unit, VFD screen etc. I cant make out what brand it is, here have a look if you can figure it out. It starts with an 'M'.http://cgi.ebay.co.uk/ws/eBayISAPI.dll?VISuperSize&item=130600015278This goes for £477.EDIT: Olsenn I am of the same philosophy too, but its not always black and white; budget is always a factor. Agilent and Kikusui also make electronic loads. No need to splash out when you can get the quality and specs you want a bit cheaper.Lets see how much we can get the IT8512B for.

author: olsenn
author_rank: Frequent Contributor
timestamp: February 06, 2012, 07:31:47 pm
content: Quotehmm, I'm not sure you understand the principle of a "DC" load: you don't download a waveform to an electronic load, that would be an arbitrary function generator, and I don't see the need for an oscilloscope???The software for the IT8511 (and all 8500 series loads) is in my opinion, excellent. In addition to the software provided from BK Precision (that's right, they make and support the Itech line) LabView drivers are also available for download. The only concearn you may have is that it costs an additional $50 from Mouser to buy the TTL-to-USB (or TTL-to-RS232) cable that is required to connect it to a computer. One plus to this cable is that it is optically isolated.The device itself is built like a brick shithouse, very robust and fully featured. It surprised me to see that the LCD readings (and those reported to the computer) are largely accurate to three decimal places (tested with my Fluke 87-V and Rigol DM3058). I've also tested it to it's full rated power capacity of 150 watts and more (it actually will allow you to run up to 200 watts or something around there). Full over-voltage, over-current, over-temperature and reverse polarity protection is in place.

author: Unknown
author_rank: Unknown
timestamp: February 06, 2012, 07:46:54 pm
content: Quote from: olsenn on February 06, 2012, 07:31:47 pmI take it in the software you can set a few 'DC' operating points (say 100R, 50R, 10R) in time and have the load run those in sequence, right? The scope for various key nodes on the unit under test for transient response.Sounds like a worthy unit, or you are a good salesman, or both.Fired off a question to Caltest. Place your bets!

author: olsenn
author_rank: Frequent Contributor
timestamp: February 06, 2012, 07:54:28 pm
content: QuoteOh, I see what you mean -- yes, you can do that. If you need to know the switch times I'd recommend you look at the datasheet first though.Thanks for the compliment, haha, I'm sure you'll like it.

author: Unknown
author_rank: Unknown
timestamp: February 06, 2012, 09:36:03 pm
content: Thanks BaW for that brand. Why did your reply ('Maynuo.') got deleted?Here is the Maynuo M9712B, similar specs to the IT8512B with some notable differences at shortcircuit resistance and pulse tests.http://www.maynuo.com/english/xpro.asp?pid=53(warning, very slow page download)I tried downloading the software but at 1.3kB/sec it was not practical.If you look at the page linked above, they have a screen cap. Does that look familiar olsenn?

author: nctnico
author_rank: Super Contributor
timestamp: April 07, 2012, 12:58:20 am
content: I recently bought two Array 3710A loads (the 150W model). They work ok for testing power supplies. Fortunately the fans only switch on when they have to. The only downside is that they use relais to switch between the two load cells inside. Depending on the load / voltage they change over which causes interruptions on the load presented on the input. I converted one the have 4mm style inputs. The build quality is OK. Actually the casing is an exact copy of old style HP equipment

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 07, 2012, 07:20:11 pm
content: Maybe use incandescent light bulbs or heaters with PWM control? The hardest part of building a large load is dissipating all the power, which is what the heaters or light bulbs do very well. A grid tie inverter can recycle a large percent of the power, but it only makes sense if you're doing a lot (as in near 24/7 burn in tests at a factory) of high power testing.

author: bsgd
author_rank: Regular Contributor
timestamp: April 07, 2012, 08:26:49 pm
content: I have 2 BK 8500 loads and I like them a lot. At first I was inclined to get an Agilent 6060B, but it was kind of expensive and getting two would cost me too much.

author: nctnico
author_rank: Super Contributor
timestamp: April 10, 2012, 11:03:08 pm
content: Here is a picture of the inside of my 3710. Note that I modified the input connectors!

author: Rufus
author_rank: Super Contributor
timestamp: April 27, 2012, 02:27:07 am
content: Inside of a Beich CH8710B.Cheap and Chinese same as the rest. I am pretty disgusted with all these loads. I haven't seen one specify a maximum voltage rating between inputs and earth. I assume they all have all the internal circuity tied to the -ve input and floating with respect to earth.Cracks me up, the BK and Itech manuals have a page full of safety drivel but neglect to tell you that if you stick 360v on the +ve input terminal you are going to get 360v on the pins of the 9 way 'D' comms connector on the back.This Beich has RS232 conversion built in but it isn't isolated, at least the Itech etc want you to buy a comms adapter which if you believe the label on it is isolated but nothing tells you why it needs to be.

author: EEVblog
author_rank: Unknown
timestamp: April 27, 2012, 03:39:52 am
content: Quote from: Alex on February 06, 2012, 04:03:53 pmI was wondering about those, they go very cheaply on ebay.Dave.

author: codeboy2k
author_rank: Super Contributor
timestamp: April 28, 2012, 12:31:41 am
content: Quote from: nctnico on April 10, 2012, 11:03:08 pmin that picture on the left hand side, note the curvy traces on the PCB. Can anyone tell me what's the design decisionthat went into making those traces like that. Obviously the shortest path is a straight line there, and it's clearwhere a straight line would go. But they didn't go straight, and I can't imagine there is anything high-speed here, soit's not a strip-line or matched impedance like that. I've also seen it done this way on the battery connections insidecell phones and home phones. In those cases, it's almost like an RF choke on the PCB, but I can't see why such an RF choke is needed here on the DC load. Anyone know why's it done that way here.

author: nctnico
author_rank: Super Contributor
timestamp: April 28, 2012, 01:35:44 am
content: The designer probably wanted to add some extra resistance. The traces go to 2 low value wirewound resistors in series.

author: EEVblog
author_rank: Unknown
timestamp: April 28, 2012, 02:34:54 am
content: Quote from: bsgd on April 07, 2012, 08:26:49 pmLooks like I might be getting a BK Precision 8500 load shortly, so stay tuned...Dave.

author: Rufus
author_rank: Super Contributor
timestamp: April 28, 2012, 04:05:28 pm
content: Beich CH8710B issue and fix.One problem I noticed with this load was significantly low voltage readings at higher currents. The photo shows the back of the input terminals and L shaped bars which are bolted on the back of them and soldered to the analog PCB.The input voltage is sensed on the PCB and I measured about 15m ohm between one terminal and the PCB and 40-50m ohm on the other. The terminals have M6 studs and the bars were fastened with a flat washer, single turn spring washer and M6 nut (which was tight).The resistance appeared to be between the terminal studs and bar so I replaced the flat and spring washers with slightly domed spring washers with a serrated surface (think they came from earthing screws supplied with a large diecast box). With that fix the resistance between terminals and PCB was about 0.5m ohm both sides.Shows bolting together two bits of metal doesn't necessarily make a good electrical connection.The washers I used were something like herehttp://www.bellevillesprings.com/serrated-safety-washers.html

author: codeboy2k
author_rank: Super Contributor
timestamp: April 28, 2012, 09:49:44 pm
content: Quote from: EEVblog on April 28, 2012, 02:34:54 am...waiting for its Tuesday...

author: bsgd
author_rank: Regular Contributor
timestamp: April 28, 2012, 10:08:53 pm
content: Quote from: EEVblog on April 28, 2012, 02:34:54 amGreat Dave, a teardown/review would be awesome!

author: EEVblog
author_rank: Unknown
timestamp: April 28, 2012, 11:25:26 pm
content: Quote from: bsgd on April 28, 2012, 10:08:53 pmThat's the idea.Will be handy for the PSU and other stuff too.Dave.

author: saturation
author_rank: Super Contributor
timestamp: August 25, 2012, 12:37:02 am
content: An interesting application of the Array 3710 and 3711:http://www.techpowerup.com/articles/overclocking/psu/161

author: T4P
author_rank: Super Contributor
timestamp: August 25, 2012, 01:19:04 am
content: That was my gripe with 95% of the Tech websites PC PSU reviews, largely inaccurate measurements

author: saturation
author_rank: Super Contributor
timestamp: August 25, 2012, 12:13:45 pm
content: It certainly can be, but I think these folks try, and IMHO honest opinion is worth more than hype from the manufacturer. But, I'm not as obsessed with PSU power supplies as these folks, so I leave that criticism for another thread!For our needs however and this thread, it appear like a good torture test of Array's lower cost electronic loads, that link is strong suggestion that Array's can hold up. Further, the demands of the design suggests the author knows what he's doing, technically, and is putting his money where his mouth is, the setup cost €10,835, €4,500 is just for the10Array loads alone.http://www.techpowerup.com/articles//overclocking/psu/161/4I emailed the author, and he's been using the test setup up for > 1 year. If you read how he tests it, regardless of the PSU, he's pushing the 3710 and 3711 to the limits of their power capacity, so as a e-load, its durable and reliable.That said he also mentions a key flaw, that are corrected in Array's newer and more costly models, 372x series: it has no remote sensing, so beware voltage drop on the leads at higher loads.I also noted on the manuals and reading the 372x manuals, the 3700 series slew rate, i.e., amps/microsecond, cannot be programmed. You can program automatic periodic load changes, e.g. cycle from 1A to 0.1A ~ per second increments, but you are at the mercy of the units inboard switching to determine the rate of change.Quote from: T4P on August 25, 2012, 01:19:04 am

author: MikeO
author_rank: Contributor
timestamp: September 06, 2012, 06:02:16 am
content: Hello all,I came across this thread while googling for a manual for a Kikusui PLZ300W electronic load. I need an electronic load for a project I took on, and am on a tight budget. I looked at the Array units and they seem nice. I ended up buying the PLZ300W, on ebay, for $360US, including expedited shipping.My main reason for making this choice was budget, and, in a previous life, I shared an identical unit with a couple of engineers and a couple of techs. I was in that lab for ten years, and that load was no spring chicken when I got there. It performed flawlessly for all the time I was there, and it was in high demand (lab was engineering department for a battery and charger manufacturer).I didn't over-think it, and went with what I know. I doubt it has the features many of you seek, but, as far as dependability and accuracy per dollar, it's a worthy consideration (if buying used).I think we all love new gear, but I've been so burned by Chinese made goods, I generally do what I can to avoid them. It may seem racist but, really, I've thrown away A LOT of Chinese made tools; frankly, I think there is some cultural differences, and they do not embrace the meaning of the word "quality" in the same way. Regardless, I did just buy that 1052E.I don't do much engineering these days, but have this one job, and need to set up a mini lab at home. I'm trying to do it for under $1000US, so as not to suck all the profit out of the job. I bought a Rigol 1052E direct from the manufacturer, two HP bench supplies (6289A, 6291A), and the PLZ300W, and, so far, with shipping, I've spent $833US. I still need a simple, low-speed function generator, and an array of test leads, but I think I'll make my budget. Considering that I've not been watching ebay for good prices, let alone hit up the HAM radio folks, but rather selected and purchased these items today, at the "buy it now" premium, I think one could do even better.Anyway, my point is, 30 year old equipment doesn't tend to inspire confidence, and usually lacks great, modern features, but the old thru-hole gear is very dependable and very repairable. Best of all, you can choose quality levels you couldn't otherwise get into the budget. The one caveat is the dark years of electronics: the previous decade. When Europe introduced the RoHS and WEEE legislation, it all really went bad. The lead free solders, tin whiskering, delaminated PCBs (from the higher heat for new solders) made for some of the worst lived electronics in the history of, well, electronics! I avoid gear from that era, whether it be an electronic load, or a car stereo. You can keep itSo, there are some opinions from some random guy on the internet.Best of luck in your endeavors.Regards,Mike O'

author: EEVblog
author_rank: Unknown
timestamp: September 06, 2012, 10:16:34 am
content: Quote from: MikeO on September 06, 2012, 06:02:16 amChinese companiescanproduce top quality products, it's just that 90% of the market seems to be the junk stuff built to the lowest price using what parts they can get this week from the markets.And likewise, western companies can get their products made in China to a high standard, but you have to drive them hard and control everything.Dave.

author: MikeO
author_rank: Contributor
timestamp: September 06, 2012, 02:00:17 pm
content: And therein lies the great value of your reviews and teardowns, Dave.Perhaps there is a bit more opportunity as well? Maybe you would consider adding some polls to the site, say a post one year and two year ownership with a few basic questions, like still working? Still accurate? Good service/support/repair/repairability? Maybe you already do, and I've failed to peruse the site before making such recommendations--can you tell I was moved to management?Speaking of which, is there anything easier than volunteering someone else for work? I think back to countless meetings with management, and getting the question, "Can't we just..."No! WE can't, cause you can't do anything! I can, but you'll fail to give me the budget and resources, and if I argue for them, you'll argue back, as if this were a negotiation, and not statement of fact. Of course, those were just the words in my head. And how would it go from there? The mechanical engineer would check out, the power supply engineer would turn down his hearing aid, the other controls engineer would get excited, knowing that it would fall to me, meaning I'd miss my other goals, making him look more productive...goodness gracious, I do not miss being an engineer in a dysfunctional company. Self-employment can be tough, but I'll take it!And therein, I suppose, is why a forum like this is so refreshing to me--it reminds me of the good side of my time as a designer: the culture of our lab. I miss the day-to-day working with my colleagues, the other engineers and techs, their mutual respect for each others unique skills, experience and education, and the willingness to offer help to one another whenever it was requested. Nice job fostering and maintaining that culture in your forum Dave.Cheers all, it's back to work for me.Regards,Mike O'

author: saturation
author_rank: Super Contributor
timestamp: September 06, 2012, 03:47:55 pm
content: An e-load was in my sights for some time too. Welcome MikeO, some comments.I concur with Dave, China can make good consumer or low end general purpose technical stuff, the reviews by Dave and others prove it. China can send a man into space they can certainly make a decent GP electronic load. The trick is finding who and what, and that's where the reviews come in.On Array: FWIW the founders of Array are Taiwanese engineers, not PRC, so they have a much more advanced design ethic, it probably explains why the build quality is more consistent with say Instek than Atten. The factory is in PRC. Array is very likely OEM for many look-alikes, such as Tekpower, IWH or CSI. I can say this because their product manuals, software, and photos of the devices [ 3710 and 3711 at least] are identical to Array's model, except for the brand name. I haven't had time to tear mine down and confirm that by looking at the PCBs.The forum has a lot of reports, but few are collated or polled. Any member can make a query and ask.One thing about PRC devices, the bolded item in your quote below, is in most instances you should expect low to none. A key feature of reviews I look for is to estimate its DIY repair-ability, which is why a tear down is most helpful. Its another reason I look at the PRC devices because they are often made with older technology, or more generic parts, and the probability of repair is higher.The Kikusui PLZ is a superior device in many ways, but the great unknown is how it was used. Power devices are likely to wear out with heavy use to its rated power, so its a bigger risk. I think a repair cost may outstrip its eBay cost given Kikusui bottom line models start over $3000. No schematic and only 12 years old or so for PLZ300W, could be challenge to self service.Quote from: MikeO on September 06, 2012, 02:00:17 pm

author: olsenn
author_rank: Frequent Contributor
timestamp: September 06, 2012, 04:16:34 pm
content: QuoteOutside of China, you can have a very high quality product made for a very high cost, or a high quality product made for a high cost. In China, you can have a very high quality product made for a very high cost, a high quality product made for a high cost, or a low quality product made for a low cost. If people outside of China want to make a very high or a high quality product, they'll just do it in their own country.

author: T4P
author_rank: Super Contributor
timestamp: September 06, 2012, 05:09:49 pm
content: Quote from: olsenn on September 06, 2012, 04:16:34 pmI don't agree. Look at rigol!

author: MikeO
author_rank: Contributor
timestamp: September 06, 2012, 05:13:40 pm
content: All interesting points.Certainly, I won't pretend buying old gear, of unknown provenance, from unknown sellers, is anything but high risk. It's a bit like buying a used car. The pics of the gear matter, the wear on the knobs, et cetera, just like the wear on the accelerator and brake pedals are more believable than the odometer. When I buy used gear, it is with the assumption that it may have been an error, only time will tell. And certainly, I wouldn't want to fail to reiterate what Saturation said, how it was used (duty cycle, and what percentage of maximum load) I cannot detect from a photo. It's a gambler's game, on the average, will I save enough to justify the risk, adjusted for the fact that I can get some better gear than what I'd buy new? And then there is the type of risk, as bad gear doesn't just cost money, it costs time, and they have different values in a home lab than a commercial one. In buying that load, my assumption is that if it fails, and I can't troubleshoot and repair it quickly, I'll be giving it away, as the repair cost will be higher than replacement.My experience with PRC manufacturing is out of date. But, I'll share some lessons... It is getting almost impossible to compete, over some volume, if you aren't doing some manufacturing in the PRC. In order to succeed with manufacturing in the PRC, you've got to maintain very high quality assurance, and quality control is generally best done outside of the PRC. Some quality assurance can be accomplished by supplying the components, but that often fails, as the components you supply are often resold, and cheaper parts substituted. It has been suggested to me that the lack of financing available in the PRC makes this a necessary model to achieve required plant improvements. Further, in the PRC, the concept of intellectual property is very, very different. I wonder, is that an effect of communism? A concept of collective ownership? We found that whenever you manufacture in the PRC, you will see your product elsewhere on the market, unlicensed, carrying someone else's name. Further, you've no legal remedy, other than if it's patented, you can get it seized at the importing country's customs, at great expense. Some would suggest, why pay for a brand name? To me, because I see a value in the quality control, and after purchase support. And because I believe in a name, that someone has pride in it, and is loathe to allow others to spend up that good will in the name of short term profits. Certainly, it's no guarantee. Goodness knows, I'm still using every Milwaukee power tool I've ever bought, except one, when it was an American company, and I burn up two a year on all the units since they've become an Asian company. All my Fluke meters are made in China, and they've seen some unbelievable abuse, so they are succeeding in manufacturing in the PRC.I think that brings us full circle. We need to depend on our colleagues, and forums and reviews like those found here on eevblog, to share their experiences, and to do what those of our ilk tend to do: take things apart. As such, I'm fortunate to have found you all.If not for this site, I'd not have purchased the Rigol 1052E. I'd probably have some chitty-chitty-bang-bang old scope with dried out caps exploding when I fired it up, and a burned screen, frustrated, and cursing my frugality.I think the one point I intended to make, and failed to, aimed more at the beginners, is that you'll never have the budget to get all you want and think you need. But, you sure will need some gear to earn enough to get close. Don't be afraid to buy some old gear and basic gear that is inexpensive. I think few would argue, the only thing that comes close to the value of a bench supply is a second bench supply, the only thing that approaches the value of a scope is a second scope (preferably analog if your #1 unit is digital).When I chose the Kikusui, it was because I didn't want to spend on a new Array unit, as that would cut my budget for a function generator; I had spent so much time researching my scope purchase, I didn't have the time to research my load purchase; so, I went with a unit which I had enjoyed a long and positive experience. Also, I was compartmentalizing my risk. If my scope fails, my project will be in big, big trouble. If my load fails, I'll get by with lightbulbs and resistors. I can think of many a project where the opposite would be true, and I'd survive the lack of a scope, but I'd need an accurate, predictable, consistent and bulletproof load. All in all, the win will be if, at the end of the job, beyond the profit, I've increased my equipment, and am that much more capable of taking on the next project, not needing to purchase that much more.Thanks for the dialogue. It's quite informative and clarifying.Regards,Mike O'

author: T4P
author_rank: Super Contributor
timestamp: September 06, 2012, 05:18:24 pm
content: Well so i saw some Vantek CA5030 loads going for 285USD w/o shipping on precisegauge and i googled it ...I didn't expect a local's (arguably most biased reviewers on earth) tech website to get a little serious but they actually use USB meters to monitor voltage WTFBut still they bet some money on the CA5030http://www.istorya.net/forums/computer-hardware/521871-behind-scenes-vr-zones-psu-testing-station-mark-ii.html#post12959202

author: ElektroQuark
author_rank: Unknown
timestamp: September 06, 2012, 06:39:07 pm
content: Ah!

author: saturation
author_rank: Super Contributor
timestamp: September 06, 2012, 10:39:00 pm
content: Very well said, MikeO. Your comments are more a study of PRC manufacturing issues using our electronic loads as a case study, I hope others take the time to read it. I agree 100% with your comments.I'm not sure if you still have manufacturing ties in PRC, but sadly, all issues you lament are still ongoing as of 2012. Not to take this thread off topic, there are discussions on other threads here about it.Quote from: MikeO on September 06, 2012, 05:13:40 pm

author: saturation
author_rank: Super Contributor
timestamp: September 06, 2012, 10:56:33 pm
content: Nice! Ed, I'm sure Gossen did their homework of this unit before putting their name on it. They haven't remove all traces of Array's name on it. I downloaded the manuals and they are clearly Array's manuals. The software is identical. Lastly, they didn't remove Array's name from the software's splash screen.http://www.gossenmetrawatt.com/gmc/english/produkte/eloadms.htm#Quote from: EdoNork on September 06, 2012, 06:39:07 pm

author: saturation
author_rank: Super Contributor
timestamp: September 06, 2012, 11:29:44 pm
content: Nice, that speaks well for Vantek, assuming the setup holds up to repeated use. Since the original article was published 7/12, time will tell if the units are as reliable as the Array. What they did looks surprisingly similar to what techpowerup's crmaris did in Greece back 2011 using Array loads instead. The only reviews VRZone has using this setup began in July 2012, so usage has not much history yet.There are many budget basic e-loads from China not available in the US: Beich as briefly reviewed below, Vantek, MH, ... here's a one stop list of several models:http://www.goodluckbuy.com/index.php?target=products&mode=search&subcats=Y&type=extended&avail=Y&pshort=Y&pfull=Y&pname=Y&pkeywords=Y&cid=0&q=electronic+load&x=0&y=0Am not sure what to make of it as a bang for buck. On the low end the price/performance is very similar to the 3710. Add S&H cost, they come out ~ $350 delivered, same price as direct from a US vendor.Itech/Maynuo/BK Precision versions [ not sure who the original is] however, are a class above the others.Quote from: T4P on September 06, 2012, 05:18:24 pm

author: T4P
author_rank: Super Contributor
timestamp: September 07, 2012, 04:52:00 am
content: It's not only themThere's tonghui, atten, Crown (Well ... Atten rebadge), ITECH ( the most expensive one out of all but you can only find them in china well of course ... BK's not going to let ITECH sell outside ) And REK

author: saturation
author_rank: Super Contributor
timestamp: September 07, 2012, 02:53:53 pm
content: Thanks. I briefly looked at them, but couldn't find Crown. Tonghui appears to be a Beich, Atten does both rebadges, and REK is an Itech, all for about the same price. It would be best to buy it from the OEM, if possible, since they would know their product best.Sample links:http://en.ebuy17.com/product/4065/http://trade.e-to-china.com/company-cCB3BA/Changzhou_Tonghui_Electronic-pBAB1G1/CH8711_Program_DC_Electroic_Load.htmlhttp://www.attenelectronics.com/Products/Power_Supply/DC_Electronic_Load/Quote from: T4P on September 07, 2012, 04:52:00 am

author: T4P
author_rank: Super Contributor
timestamp: September 07, 2012, 04:15:04 pm
content: You can find them all over at taobao.

author: saturation
author_rank: Super Contributor
timestamp: September 17, 2012, 02:27:23 pm
content: There are several threads discussing China branded e-loads so I'll summarize points. Rufus suggests the brands mentioned have much similarity, one thread suggests the BK/Itech/Maynuo/ older Array model are designed by the same person, but I think others are distant copies, some changes don't look optimally thought out, but they seem cheaper to implement. So for example, the Beich lacks a quality ethos you see in common with BK, Itech, Maynuo or Array.Here's a comparison of Rufus' Beich CH8710B photo, a clearer photo of an Array [both rated at 150W], and a screen grab from Dave's BK 8500 review . Sorry its big, but the details are needed to contrast the 3.The most obvious on the PCBs are thermal management strategies. The BK and Array use 2 sets of forced cooling heatsinks, while the Beich, rated for the same wattage as the Array, uses one. It may not be a problem if the fan cfm is >=2x a single Array set, but clearly the Beich case is missing one set of fan/sinks.Since all 3 claim to have thermal overload protection, if the fans can't handle the load I presume the load with be cut off until they cool down, so if the Beich's copied those features it has a backup plan since it relies on a single fan for all its cooling.On both the Array and BK units, the low-ohm power resistors [ the twisted coils of wire in the BK] and heat sinked TO220 device are within the airflow stream of the fans. There are cutout vents on the side of the BK for intakes, as well as a ventilated bottom chassis. On the Array, the vents are on the bottom of the PCB both as powered intake fans and passive holes.On the Beich, while the bottom seems quite 'open' to ambient, the fan is on theoppositeside of the input resistors [ the yellow A in the photo], and resistors on the load board marked C, are on top of the PCB, these resistors will have to rely on indirect airflow for cooling. Beich could have put the single load module on the right side to help cool down those resistors. On the Array, similar functioning resistors on the load board marked a,b are on the bottom of the PCB, are not visible because they are in the airflow stream of the fans.In thermal management, overdesign is best, because heat dissipation will suffer drastically if ambient temperature is higher [ such as in hot climates] or obstructions to vents [ such as placing the unit against a wall].SafetySince few are UL, ETL, TUV etc., certified one has to rely on the CE mark or doing one's own due diligence to determine what limitations to put on these eloads.Both the BK and Beich have line voltage switched on the PCB; the Array uses a separate switch and only low voltage appear on the PCB. Not big issues, but its safer to keep line voltage separate from low voltage lines in case high voltage transients in mains voltage enters the unit.Both Array and BK add MOVs as surge input protection, and the binding posts, which potentially can contain higher voltages, are kept free of other lines as potential arc points, the only wire nearest it is a ground wire quite some distance away. The Beich seems to only have high voltage capacitors on the input, and there are a bunch ribbon cable crossing near its binding posts; one could move them away a bit as an arc may not be lethal to the operator but more lethal to the control electronics.Modern high voltage design prefers cutout to control line clearances on PCBs. Eyeballing, the creepage distances on the Array and Beich are acceptable but adding cutouts would be better.The Array has surprising design elements that provide safety in redundancy but at greater cost.For example, Array has two thermal sensors for each load cell, 2 fans for each cell. I'm not sure but suspect each fan is controlled by each cell.The Array design takes trouble to add separate ground wires to the chassis walls, and terminate them to the same ground point. This insures that the ground lines have lowest impedance path, rather than bolting it to the chassis.I'm intrigued by the x6 MOSFETs at the input. I'm not sure how its configured as a switch, but it gives a banked series rating of 330V at 110A. I'm guessing its either a high voltage reverse input protection but how it does it I'm still examining, and will report back. A similar configuration is not present on the BK or Beich.So in conclusion, even if Beich units copy another's design there is a big difference in implementation, considering the list price is often similar to Arrays.The Array seems very competent in hardware for what its designed to do, and for small labs, its use of through hole, and fairly generic parts makes its easier to service DIY. More later as I finished a detailed review and performance and finally safety test.

author: robrenz
author_rank: Super Contributor
timestamp: September 17, 2012, 03:50:17 pm
content: Wow saturationso much for BK just being a rebrand. Thanks for the pictorial comparison.

author: saturation
author_rank: Super Contributor
timestamp: September 17, 2012, 08:31:22 pm
content: I'm fairly intrigued by these e-loads, it has the look of being done by a very small team, even one man [ kmel in another thread suggests the designer Xiao Tony was formerly at Array, and the 3710a looks like an early version of models later of Itech/BK/Maynuo.]However, for bang for buck, the Array is looking like a very decent box if you don't need to test systems using constant voltage, and can deal with its buggy software.T4P provided some links to vendors in China per se, via taobao.com. Units from Beich, Maynuo and Array for the same wattage are priced near the same, even if Array is an older design. I think its main feature is its likely built like a tank and can take abuse, and Array is the only model you can get in the USA directly as OEM for other brands, like TekPower.Quote from: robrenz on September 17, 2012, 03:50:17 pm

author: saturation
author_rank: Super Contributor
timestamp: September 20, 2012, 04:14:24 pm
content: I've just posted a hardware teardown of the Array 3710a dc electronic load. My model is rebadged as Tekpower.http://www.flickr.com/photos/igsaturation/sets/72157631565608376/There are 31 photos so the above link is faster. It would be best to comment on this thread so the discussion has a larger audience than the Flickr site. I'll steer any comments on Flickr back here or mirror replies.Since I have confidence the unit is built well, its now undergoing stress testing and I'll post a functional review later on this thread.

author: free_electron
author_rank: Super Contributor
timestamp: September 20, 2012, 06:20:23 pm
content: ah , good. i just bought a 'out-of-spec' 3711 for cheap on fleabay. so i can compare.

author: saturation
author_rank: Super Contributor
timestamp: September 20, 2012, 06:45:16 pm
content: Nice, and congratulations. I'd be interested in your comments, free_e-. I was wondering what happened to this unit.http://www.ebay.com/itm/TekPower-3711A-TP3711A-Programmable-DC-Electronic-Load-0-360V-300W-/290771559411?pt=LH_DefaultDomain_0&ssPageName=RSS:B:SHOP:US:101&hash=item43b355e3f3&nma=true&si=4%2FoYUNwtxMPRuUXZmUBrIJTg4og%3D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557If its you, its in good hands.I wonder if the 150W, which is really 200W, is just crippled in firmware and is in hardware a 300W. Much of its components suggest it is. A photo of your PCB and your comparison would clear it up easily, when you've time to get to it.Quote from: free_electron on September 20, 2012, 06:20:23 pm

author: LaurenceW
author_rank: Frequent Contributor
timestamp: September 20, 2012, 11:50:30 pm
content: Greetings all,I've just posted a rather wordy initial impression of my Maynuo electronic load, herehttps://www.eevblog.com/forum/product-reviews-photos-and-discussion/why-is-bk-precision-still-in-business-bk8500-programmable-load-oem-found/30/I'll get the lid off this weekend, and grab some pictures.

author: saturation
author_rank: Super Contributor
timestamp: September 21, 2012, 11:21:47 am
content: Excellentreview, must read for anyone considering an eload. Please keep it up, and as many pictures as you can! I'll post comments on that thread rather than here.Quote from: LaurenceW on September 20, 2012, 11:50:30 pm

author: free_electron
author_rank: Super Contributor
timestamp: September 21, 2012, 01:07:50 pm
content: Yep. Me. Snatched it for less than thatI have some 'reverse engineering ' info.The meanders on the pcb are there for a purpose. The two powerfets at the back have their own 0.1 ohm sense resistor to close the loop. These two resistors share a single trace on the board that is via-stitched between top and bottom layer and comes to the front of the board. The meanders on the front resistors inject the same trace length to the star point. The reason is load balancing. The pcb trace resistance would be different between front and back and the front fets woul pull more current than the back. Deliberate operation. Good design.The bank of 6 mosfets on the main board is for range switching.The use either 0.2 ohms for current measuring , in series with 0.02 ohms ( five 0.1 in parallel ). At high current they turn on the bank of six mosfets to short the 0.2 ohms out.A relay toggles between the sense points. ( strange.. No analog mux ... Probably because there is a post divider protecting against large voltages.. )My machine is off in the voltage measuring department. The programmed and measured currents are correct. The voltage measured on the terminals is wrong , so it probably needs adjustment.The sticker said. Cannot adjust , but they didnt even try.... None of the pot seals are broken and this machine has no electronic calibration.... Lazy callabs...

author: saturation
author_rank: Super Contributor
timestamp: September 21, 2012, 03:14:53 pm
content: Congrats on the good price on the eBay item.Nice. Those are great insights, I wasn't entirely clear on the meanders nor the 6 MOSFETS.Volt adjust is fairly straightforward. The cal information and software can be downloaded from Array's website. The software is not well made and unreliable for controlling the device but its fine for data collection.But if anyone can write a better version! I'd be happy to test it outNote the reverse input protection causes non-stop beeps and a warning on the LCD but it shorts the load rather than cuts it out, so it will draw the full output. It'll be a shocker if you were testing high current DUT and had reversed the leads in error.Quote from: free_electron on September 21, 2012, 01:07:50 pm

author: free_electron
author_rank: Super Contributor
timestamp: September 21, 2012, 07:09:32 pm
content: Good ! got the info. will hook it to the calibrator over the weekend.I download the software.... typical national instruments tripe ... made in CrapWindows or Crapview..I'll write my own. Just need to find the comms adapter ....

author: saturation
author_rank: Super Contributor
timestamp: September 23, 2012, 01:52:02 pm
content: I've completed the functional testing. In a nutshell, I ran 90W for >1 hour and checked the response of the electronics, the load distribution between the modules, and the stability of the readings. During that time I ran all the modes, CC, CR, and CP but kept to about 90W or more. I programmed a series of variable loads, going from 0.01A to 2.5A and various level between and ran for 30 min. Temp was measured with an IR thermometer.Loads on the power MOSFETs appeared evenly distributed as measured through its voltage across load resistorsthe Array can slew far more ~> 1A/1mS as measured to the response to variable loadingThe unit held its calibration as monitored by Fluke 87Vs checking current and voltagesThe fans are a soft hum and not a harsh blowing whine when at full powerThe fans engaged at 40C, and keep the unit at a constant 38C. It shuts off at 35C, the difference being as thermostat hysteresis. Each load module was only1C warmer at the center of the heat sink compared to the end, and -4C at the exhaust end of the vents.The dual supply linear regulator ICs warm up to4050C, while the 5V supply peaks at 64CThe most annoying drawback is the voltage drop across the hook up cables so one will have to compensate for itThe interface is fairly simple, and direct. Rare glitches happened when playing with button and rotary control adjusts, the system would then jump to init mode, which happens quickly so its not a bother, 1 sec or less. All the saved defaults remain untouched.

author: T4P
author_rank: Super Contributor
timestamp: September 23, 2012, 06:30:41 pm
content: Good info thanks saturation, so the question still begs ... Maynuo M9712 OR Array 3711ABoth are around the same prices with the Maynuo being newer but the maynuo is only 150V and has battery test feature (Of course my prices are quoted from china directly)Forget about the CA5030 from precisegauge, i can get a 3711A cheaper than the CA5030

author: nctnico
author_rank: Super Contributor
timestamp: September 23, 2012, 07:05:04 pm
content: Instead of one 3711A I bought two 3710A devices. They can be parallelled to handle more load or put in series for a higher voltage or used for two different projects at the same time.

author: T4P
author_rank: Super Contributor
timestamp: September 23, 2012, 10:06:45 pm
content: I'm still thinking whether the battery test function is worth the extra dollars ...Quote from: nctnico on September 23, 2012, 07:05:04 pmSure but they aren't exactly light or half the price in any way so i'd get a single 300W unit plus shipping's not free. so yeah (40-50bucks for 4.5kg)

author: LaurenceW
author_rank: Frequent Contributor
timestamp: September 23, 2012, 10:12:19 pm
content: T4P, i should declare "an interest" first - I've just bought a Maynuo M9712B! (300W, 500V 15A)In looking at the Array equivalent, a few points.The Maynuo specs quote almost an order of magnitude better basic accuracy (Maynuo0.03%+0.05%FSVs Array4.00~35.99V?0.2%+30mV)The Array generally resolves to three decimal places (1ma, 1mV) while the Maynuo stretches to four for voltage (0.1mV) and five for current (10uA!!), BUT that last current place ismost iffy- call it four decimal places (100uA)The array does boast a lower minimum or short circuit resistance; this is a function on the lower voltage mosfets. (The 500V Maynuo can "only" go down to about 0.25 Ohm)The 500V Maynuo can only handle 15A, Vs the 360V Array's 30A. What do you reallyneed?The Maynuo battery test function is an eye-opener; especially if you use a lot of rechargeable cells, and they don't seem quite as efficacious as they once were. The battery test function quickly weeds out dieing cells, with poor mAhr figuresThe Array comes with wingsWhy, I wonder? The Maynuo sports a front rubber bumper.The Maynuo number pad is upside down (GRRR), but the Array number pad is even WORSE! Does this matter? Well, I find it slows down your direct input typing speed a lot, yes. To see how number pads SHOULD be laid out, look at an Array 3720 series (but don't look a the price - ouch)The Maynuo sticks out about 120mm further (deeper) than the Array. How deep is your test bench?The Array boasts FOUR fans to Maynuo's two. I suppose it depends on how big a fan fan you are. (Maynuo seems to manage fine with its internal pair)The Maynuo includes a V-set function (Think: 300W Zener Diode!) while the Array appears not to offer this.The Maynuo allows you to set a number of set points (i.e currents) and then switch or slew between them, so that you can observe how your power supply performs under transient load situations. I cannot see that the Array offers this. I am interested in transient performance, but your applications may not need this.The Maynuo is about 50% more expensive than the ArraySo I think that the Maynuo is " mostly winning" here, but it depends on your budget and whether you feel you actually need these extra features.

author: T4P
author_rank: Super Contributor
timestamp: September 23, 2012, 10:59:27 pm
content: Quote from: LaurenceW on September 23, 2012, 10:12:19 pmGreat! Didn't notice that.Quote from: LaurenceW on September 23, 2012, 10:12:19 pmHmm ... Do i need more than 1mA reso? nope. lolbut i definitely need more than 0.25Ohms so that rules the M9712BoutQuote from: LaurenceW on September 23, 2012, 10:12:19 pmAh ... i feel the need for 30Amps ...Quote from: LaurenceW on September 23, 2012, 10:12:19 pmi was going to buy ahttp://dx.com/p/imax-b6-2-5-lcd-rc-lipo-battery-balance-charger-100-240v-us-plug-35190?item=2balance charger for it's main purpose but it's also good for testing it seemshttp://dx.com/p/imax-b6-2-5-lcd-rc-lipo-battery-balance-charger-100-240v-us-plug-35190?item=2Quote from: LaurenceW on September 23, 2012, 10:12:19 pmThink Cessna-182 vs Bugatti VeyronQuote from: LaurenceW on September 23, 2012, 10:12:19 pmYarr matey, the 3721A costs 100$ more than the M9712BQuote from: LaurenceW on September 23, 2012, 10:12:19 pm600mm but i like 300mm for my actual space but i can let it sit on the edge, well then i'll take the maynuoQuote from: LaurenceW on September 23, 2012, 10:12:19 pmI like fans. The more the better, but ah wellQuote from: LaurenceW on September 23, 2012, 10:12:19 pm

author: saturation
author_rank: Super Contributor
timestamp: September 24, 2012, 01:51:40 am
content: Just checking tabao its amazing they are near the same price. If what you need works within the limitations LaurenceW very well summarized for Maynuo, you get more for your money. What is cut to reduce costs? We know it works well now, but will it affect the Maynuo durability over time? I am impressed they are moving fast, my speculation would be they wouldn't risk a bad reputation on a fragile product since many of its product are variations on a common theme, its eloads, and if one performed badly, it reflect on all of the others as well.OTAH, Array is less speculation on durability . The only reason to get an Array is the few areas it excels are areas you require. Gossen-Metrawatt thinks its built well enough to put their name on it, crmaris from tekpowerup.com uses 7 units for his many PSU reviews spanning > 1 year, and its been in production for ~ 10 years.Although a push button AH test is convenient, you are better testing AH with a discharge curve, as the curve's shape also gives you a more complete health check of the battery. The Array can do it with external software compared to the push button of the Maynuo, but you still need to connect either to a PC to collect the data to generate the curve, so include the interface adapter too in your cost [ in the Tekpower I bought, all the accessories were included in the price.]Quote from: T4P on September 23, 2012, 06:30:41 pm

author: T4P
author_rank: Super Contributor
timestamp: September 24, 2012, 04:24:46 am
content: Well the RS232 interface cable is quite literally cheap, compared to the prices fluke charges for a rs232 interface cableBut yeah, one area it seriously lacks is V-set.

author: saturation
author_rank: Super Contributor
timestamp: September 25, 2012, 03:44:35 pm
content: You mean constant voltage?Quote from: T4P on September 24, 2012, 04:24:46 am

author: free_electron
author_rank: Super Contributor
timestamp: September 25, 2012, 04:37:47 pm
content: 3711 Adjusted and fully in-spec now. stupid callabs 'can't adjust' ... too lazy to open the box or download the cal manual... ah well their los, my gain.

author: saturation
author_rank: Super Contributor
timestamp: September 25, 2012, 07:38:28 pm
content: Great! I figured that was the case. Another advantage for owners is that the Array's don't need much in terms of high end metrology gear either, and is easy to self maintain; one can even make small adjustments on the fly while the unit is operating to compensate for settling, due care taken naturally.Looking forward to your progress and to LaurenceW's updates on his close case firmware based calibration his new Maynuo for comparison.Quote from: free_electron on September 25, 2012, 04:37:47 pm

author: T4P
author_rank: Super Contributor
timestamp: September 25, 2012, 08:56:52 pm
content: Quote from: saturation on September 25, 2012, 03:44:35 pmYes

author: saturation
author_rank: Super Contributor
timestamp: September 27, 2012, 06:48:39 pm
content: Yes, that has pros and cons, its not entirely a loss. Since V and I are related phenomena, tests meant for CV can be done with CC for practical reasons [ that is, not following the manufacturers precise test protocol which requires CV but getting the same result ] e.g. plotting a V x I curve for a battery or PSU. However, it may not be possible to to test NiMH chargers; if it has input protection, it will first check output voltage from the load before it switches on, so most good chargers will see the connection as open circuit or short circuit and refuse to start.Quote from: T4P on September 25, 2012, 08:56:52 pm

author: saturation
author_rank: Super Contributor
timestamp: September 28, 2012, 02:36:07 pm
content: Final burn in report:The Array 3710a has been running ~ nonstop for almost 3 weeks, 24/7, and all the internal components are holding <= 50% of their rated operating temperature whether quiescent or under load. This speaks well for long term durability. The power MOSFETs are held at 40C or less. I've also finished over 20+ hours of load testing, 4 cycles each of 2x NiMH battery packs drawing between 20-40W each, and the interior temps stay <= 40C while operating at room temperature 25C, fans kick in as needed and do a good job in cooling.

author: saturation
author_rank: Super Contributor
timestamp: October 01, 2012, 12:36:23 pm
content: I ran into this today:https://www.tmatlantic.com/e-store/index.php?SECTION_ID=367Another Array rebrand for USA buyers. The newer model is the lowest price so far I've seen for the 372x series.

author: T4P
author_rank: Super Contributor
timestamp: October 01, 2012, 12:40:08 pm
content: A whole new design with 250W for the base modelAt least they addressed the lack of CV and added a shitload of modesI guess it isn't designed by Xiao Tony right?

author: saturation
author_rank: Super Contributor
timestamp: October 01, 2012, 01:57:08 pm
content: The AEL-8321 is likely the higher end 400W model, Array 3721a. I hope someone one day tears it down, because it appears to have different capabilities from the BK, Maynuo or Itech models 85xx series. Anyone can compare just searching tabao.com that the price is very competitive with local China prices, particularly once you add in S&H, so if they charge more it might be made quite differently, better I hope.Spec wise the AEL-8310 appears as the Array 3710a entirely.Quote from: T4P on October 01, 2012, 12:40:08 pm

author: LaurenceW
author_rank: Frequent Contributor
timestamp: October 01, 2012, 09:18:38 pm
content: ... and the numeric keypad is laid out properly -Hurrah!

author: Katalyst
author_rank: Newbie
timestamp: November 05, 2012, 02:34:43 pm
content: Hey guys,I am new to this forum and am so happy I have found it. I have read every post you guys have written about electronic loads.I am currently working with an Array 3711A and am not very happy with it. It works great for discharging but I am having serious problems with the remote control. I would like to do some basic control using MATLAB and the constant resistance function in this device but I have serious doubts about it's functionality for this purpose. I have noticed that when the device is programmed at lower resistances (<250 Ohm), it produces erroneous current measurements. Could this be to do with the input terminals? The device was previously used.Can anyone recommend a load which may be better for electronic control? I am considering a BK Precision but am not sure yet.Thanks,Katalyst

author: saturation
author_rank: Super Contributor
timestamp: November 05, 2012, 03:34:18 pm
content: Great to find another interested reader. The native software is buggy but crmaris has made a customized programmed suite to remote control 4x 3711a and 3x 3710. This suggests to me the drivers are OK. I collect data using the battery charger software but if I try to control the unit by sending commands using the native Array software, its erratic. It works accurately when operated via the keypad for all the supported modes, C, R, and W. I'll recheck your ohms issue.http://www.techpowerup.com/articles/overclocking/psu/161A previously used eload can be problematic as it can be damaged if misused, or abused.Quote from: Katalyst on November 05, 2012, 02:34:43 pm

author: robrenz
author_rank: Super Contributor
timestamp: November 05, 2012, 06:07:12 pm
content: Anyone know of any guides/manuals for the actual setup for using using a bipolar operational power supply (4 quadrant) as an electronic load. Specificaly how to accomplish CC CV CR CW modes of operation. I realize some of these modes may require additional circuitry to control the source/sink unit. I just got a new unused TDK/Lambda/Electronics measurements inc. BOSS20-10-1-D-PM Bipolar Operational Source/Sink Power Supply ±0 - 20V, 0 - 10A off Ebay.I am not looking to be spoon fed, just get me pointed in the right direction.

author: saturation
author_rank: Super Contributor
timestamp: November 05, 2012, 06:43:45 pm
content: Hi robrenz,It may be described in manuals for the 4-quadrant supply you have. As example, Agilent N6700 Modular Power System SMU user manuals describe the adjustment to provide CV and CClikemodes. Called downprogramming, the main drawback to using such supplies is that if the source stopped sinking current the PSu could then start supplying it to the source [ it could be programmed to not do so, but it depends on your unit], and could be a problem. Note capability differs in other members of the SMU family, mostly are capable of CC but not CV. I'm not sure about CP. The N678xA manual describes using it as a CV or CC sink.Quote from: robrenz on November 05, 2012, 06:07:12 pm

author: peter.mitchell
author_rank: Super Contributor
timestamp: November 06, 2012, 02:13:31 am
content: I just saw this;http://www.ebay.com.au/itm/150792412128and thought immediately "well, someone must have held a grudge against those loads"

author: saturation
author_rank: Super Contributor
timestamp: November 06, 2012, 12:46:44 pm
content: Its certainly taken a beating, chances are its far worse internally. Many eBay used eloads are harder to spot, it looks good on the outside but its taken a beating on the inside. If the driver MOSFETs or transistors were run in a hot ambient lab the lifespan of those power devices will be much worse than one kept cooler; likewise those used Prodigit units are from Israel? so its naturally a hot climate too; even as parts one thing to worry about is unobtanium, so even if cheap rebuilding a $3k eload on eBay may not be possible.That's one advantage of the Array tear down, except for the firmware, all the parts are generic, particularly the ones that will likely wear: power MOSFETs, sense resistors.Quote from: peter.mitchell on November 06, 2012, 02:13:31 am

author: reagle
author_rank: Unknown
timestamp: January 26, 2013, 06:01:54 pm
content: Just picked up a used Tekpower branded 3710A. So far so good, though menus and beeps are a bit annoying. So is the lack of pulsed load mode, but I knew that going in. Will be taking it apart soon to check out the build quality on this one.Does anybody have a part number for the RS232-USB adapter ?

author: T4P
author_rank: Super Contributor
timestamp: January 26, 2013, 06:14:20 pm
content: Pretty sure it's the same as the Array ones.

author: saturation
author_rank: Super Contributor
timestamp: January 26, 2013, 09:16:37 pm
content: Part numbers vary by who relabels the model, but theCSI ones are here:http://www.circuitspecialists.com/dc-electronic-load-csi3710a.htmlQuote from: reagle on January 26, 2013, 06:01:54 pm

author: reagle
author_rank: Unknown
timestamp: January 27, 2013, 04:49:54 am
content: Looks like P/N 3312 for the USB version is universal across the brands.On a related topic, in Saturation's teardown pictures rack handles are shown as part of the accessories, separate form the unit. How are they mounted to the case? I am trying to get them removed, and it does not appear possible without taking the unit apart

author: saturation
author_rank: Super Contributor
timestamp: January 27, 2013, 12:49:42 pm
content: You're right on the PN#, I stand corrected. The fit on the handle covers are most impressive for a made in China, its very tight and seemless. You'll likely mar it opening it, but it can't be helped.On the arrow, use the finest and strongest knife or screwdriver to insert it between the grey cover and the white body, then twist, it should snap off the unit. Underneath it are the mounting screws. I forget where the snap is, try A first, to see where the most give is, it will move off frontward. From B, it will snap off to the left, based on the picture.Quote from: reagle on January 27, 2013, 04:49:54 am

author: reagle
author_rank: Unknown
timestamp: January 27, 2013, 02:27:45 pm
content: Thanks, worked like a charm- I used a wide metal putty knife. The covers are latched along the front edge, so I went from the back twisting and lifting.

author: saturation
author_rank: Super Contributor
timestamp: January 27, 2013, 02:54:20 pm
content: Nice! and no injury! Putty knife is it. Thanks for the close ups and description, the manual says nothing about how to assemble or disassemble those handles.

author: reagle
author_rank: Unknown
timestamp: January 27, 2013, 11:31:36 pm
content: Yes, and I was very leery to start pulling on them not knowing which part actually comes outIt's much better now without the handles, as it fits on my workbench and does not get in the way. Next step is getting serial interface adapter and either stock software or playing with the one mentioned here and tweaking it to my needs

author: reagle
author_rank: Unknown
timestamp: February 12, 2013, 03:19:50 am
content: Just picked up the Array USB to TTL interface, and promptly tore it down.Looks pretty standard- a USB- serial bridge + opto isolation. Overall quality is not bad, except for no-clean solder flux residue on the back.Edit: Umm, except the USB connector is type A. I didn't realize that until I tried to plug it inDB9 side pinout (for those playing along) is:1: 3.3V2: TX3: RX5. GNDI don't think any other pins are used

author: reagle
author_rank: Unknown
timestamp: February 27, 2013, 04:17:06 am
content: Finally got all my cables in order and started playing with the software. Has anybody been able to get Discharge software to actually turn off load when end voltage is reached? I tried it quickly with a power supply and it just kept going. On the second thought, i don't see any "OK" or the like button to confirm that I entered the number. Ideas? "Smoking gun" picture is attached

author: saturation
author_rank: Super Contributor
timestamp: February 27, 2013, 02:20:38 pm
content: I've used it quite a bit since I got it, however the software is just short of garbage.Use the "discharge" softwareonlyto collect data that it then ports to excel. Other that turning the test ON, do not control the Array with its 'discharge' or the main software; I found them both unreliable, the discharge one is the least worst of the two. You may have to press the buttons several times to get a response and this is not related to the baud rate either. Check the status lights of the USB-TTL interface to insure data is going each way.You'll have to experiment with the data capture rate to find the best for you if you want lots of data points, I think 100ms/point is the limit for practical collection. Its fairly reliable at 1sec.When running and collecting data confirm status not with the PC software but on the Array unit LCD.Set your shutdown voltage, or any programmed parameters you wish, through the Array unit itself. If you use the PC software, press self control to reactivate the Array keyboard. I can do pretty much everything through it, the firmware of the eload is reliable.

author: reagle
author_rank: Unknown
timestamp: March 01, 2013, 02:00:42 am
content: That's pretty much what I've been doing. Might have to get off my rear end and write something less sucky for general use

author: saturation
author_rank: Super Contributor
timestamp: March 01, 2013, 11:51:24 am
content: If you write new stuff, I'd be happy to test it for you, me alas, no time. One user wrote an extensive suite for it to suggest the hardware is stable to write a good application.http://www.jonnyguru.com/forums/showthread.php?t=7178and used that design, an array of 10 array loads working together, in his reviews:http://www.techpowerup.com/articles/overclocking/psu/161Quote from: reagle on March 01, 2013, 02:00:42 am

author: reagle
author_rank: Unknown
timestamp: March 01, 2013, 12:07:34 pm
content: Just ran a discharge test on a replacement cordless phone batteryAll went well and it stopped exactly at the voltage set as a minimum input. Their stupid logger crashes though when trying to actually save data. Yep, writing own may just be the answer. I'll post about it on the EEVblog once I get around to that

author: TPI
author_rank: Contributor
timestamp: July 14, 2013, 12:29:05 pm
content: [Apologies for resurrection of this topic]But I have one quite simple question that I haven’t been able to pin-point an answer for. Or are just plain blind.Are Atten ATZ3710A and the ARRAY 3710A as well as the other variants all identical except for the casing and labels (plus included extras which may come with the device)Are they made in the same factory just finished off with a different case ? so it wouldn't matter if you had an ATTEN over an ARRAY ?

author: saturation
author_rank: Super Contributor
timestamp: July 14, 2013, 12:46:23 pm
content: No apologies needed, I think resurrection old topics in electronics is a valid action because why have multiple threads on the same device, concept or idea scattered throughout the forums?I have not seen the Atten personally, but the probability is high they are rebadged Arrays. The Array design isn't as feature rich as the Maynuo or BK design, so there is less incentive to clone the old Array as the Maynuo, e.g. Beich. If you are buying locally, that would be ideal because you can easily open it and compare the PCB and if suspicious, return it. If you are buying international it would be more difficult to return any brand back to the dealer, so getting the Array branded one would be the least risky.BTW, since I posted my review the Array is working perfect, except for the annoying software; once you learn to work around the bugs, the software does the job.Quote from: TPI on July 14, 2013, 12:29:05 pm

author: all_repair
author_rank: Frequent Contributor
timestamp: August 11, 2013, 05:08:16 pm
content: Finally decided to stick with Array for my additional piece of loader. I had my first piece of 300w Array eloader for more than 3 years now, and it have been working reliability so far. Usage is about 1 day per week.Fan can be quieter, and voltage readings can be more accurate. But at the end of the day, guess they are not so essential features as a loader for me.Wondering the remote senses are for the PS under test right? So just a parallel pair of connection from he load sockets, right?Ps: main reason to go with array is so I dont end up having to many types of equipment unnecesarily, and Array still the most value for money from my lSearch.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: August 11, 2013, 08:20:00 pm
content: Quote from: TPI on July 14, 2013, 12:29:05 pmActually, thank you for bumping this. I had looked for t before but I couldn't find it. Here is a link to a thread where I posted my great experience with Array customer service.https://www.eevblog.com/forum/testgear/great-customer-service-from-array/They really impressed me with their attention to service for something so minor.

author: saposoft
author_rank: Contributor
timestamp: November 10, 2013, 10:30:43 pm
content: If anyone is interested in programming and/or use the 3710A E-Load with a computer you can find a simple program that can set current, start and stop the load and read values from the E-load in my website , source code included, only for hobby/personal use.It's still partially in Italian sorry , but pretty simple to understand.https://sites.google.com/site/elettronicaarduinoesperimenti/have fun and do some solderingAlessandro

author: metalphreak
author_rank: Frequent Contributor
timestamp: November 13, 2013, 01:05:50 pm
content: Atten mostly stick their name on existing products. They also sell a line of DC loads that are identical to the Maynuo DC loads, right down to the Maynuo badge on the front next to where they slapped the Atten logo!

author: ted572
author_rank: Frequent Contributor
timestamp: January 27, 2014, 08:02:11 pm
content: Installation of, and using of ARRAY 3710A/11A Software under Windows 7 x32 or x64 OS:Also applies to ATTEN, etc. versions of the 3710A/11A Electronic Load software, and documentation listed below in Note 2.1. Right click on 'Setup.exe', select 'Properties', '', Check (x) 'Run This program in compatibility mode for:', select 'Windows XP (Service Pack 2)'*, , ''. Note: * DO NOT select 'XP (Service Pack 3)'.2. Right click on 'Setup.exe' and select 'Run as administrator', and continue with the installation.Note 1: If this software had previously been installed in Windows 7 without following the above procedure, un-install it fully by also cleaning the Registry either by using an Un-Install App. (preferred), or using Windows un-install function followed by using the file/registry cleaner of CCleaner.exe (freeware, available at:www.piriform.com), and then re-install as detailed above.Note 2: The most current 3710A/11A Documentation and Software is available at:http://www.array.sh/yqxzcnE.htmUnder: 371X Series DC electronic loads. Use of the following is suitable for use with all of the different 3710A/11A OEM versions as the original design/build was by ARRAY.3710/11A User's Manual, version 3.0, dated Dec. 20133710A Eload Software, version 3.3, dated Aug. 20113711A Eload Software, version 3.3, dated Aug. 20113710/11A DISCHARGE Software (for Battery Analysis), Version 2.0, dated May 20053710A/11A Calibration procedure, version 2.0, dated Dec. 20133710A/11A Communication Protocol for PC, version 2.0, dated Dec. 20133312 USB Adapter Drivers. Go to bottom of page under: Others, 3312 DRIVER.* The ARRAY software is considered by some to be buggy, although once you become familiar with it's intended purposes and limitations it's quite acceptable.Note 3: The ARRAY 3312 USB Adapter with cables is available for a little less than $34 with 2 day USPS shipping at:http://www.mortoncontrols.com/index.php/labequip/accessories/3312.html

author: ted572
author_rank: Frequent Contributor
timestamp: January 30, 2014, 01:59:08 pm
content: Re. The ARRAY, ATTEND, etc 3710/11A Electronic Loads:To expand our software options with more capability and/or ease of use, does anyone know of any third partyWindows softwarefor the ARRAY, ATTEN, etc. 3710A to use in place of the ARRAY 'E Load' and/or 'Battery Discharge' software? Perhaps even something you developed, etc.

author: reagle
author_rank: Unknown
timestamp: February 09, 2014, 11:47:44 pm
content: I am working on a piece of software to talk to it now. Most likely will be in Python, so it should be cross-platform. One annoying thing I noticed is the lack of minimum voltage command in the protocol. I can set Vmin on the front panel, but there does not appear to be a command listed for doing the same serially. Sniffing traffic when running their own software does not show any commands being sent. I wonder if they look at Vmin setting on the PC end vs reported voltage and just turn the load off..

author: ted572
author_rank: Frequent Contributor
timestamp: February 12, 2014, 12:02:04 am
content: Quote from: reagle on February 09, 2014, 11:47:44 pmI'm looking forward to hearing how your application works out for you. Good luck.

author: reagle
author_rank: Unknown
timestamp: February 27, 2014, 04:18:54 am
content: It's a slow going since I am learning the language while at it. So far I can talk to the load and get and parse data it sends back. At this rate, check in a yearThough we can start a wish list of the features. For now this is all command line - start, run, maybe get log data type of a thing

author: nctnico
author_rank: Super Contributor
timestamp: February 27, 2014, 10:07:03 am
content: I wrote a command line discharge tool in C++ which also produces a CSV file you can import in Excel. I'll try to zip it and post it in a few days. It can compile on Linux and Windows.Edit: attached source code. It is an Eclipse project and compiles for Linux. It can also be compiled for Windows but it may need some tweaking (defining WIN32). When compiling make sure wxserial/linux and wxserial/win32 are excluded from compilation. The files in these directories are pulled in by including them.

author: saposoft
author_rank: Contributor
timestamp: March 09, 2014, 07:03:59 am
content: I have a small utility to characterize batteries using an Array 3710A e- load .It works much better than the provided software .Have a try it's freehttp://sites.google.com/site/elettronicaarduinoesperimenti/

author: ted572
author_rank: Frequent Contributor
timestamp: March 13, 2014, 10:41:45 pm
content: Quote from: saposoft on March 09, 2014, 07:03:59 amI would very much appreciate it if this was also available to work in Windows XP and 7 for x32 & x64 hardware.Thanks for any consideration of this.

author: battery
author_rank: Newbie
timestamp: March 14, 2014, 03:57:39 am
content: Im new to this forum but had a read through the electronic loads posts. Some great reports. Im looking at getting an E-Load to mainly test various battery types but mostly Lead Acid up to 250 Ah or so. Looking at either BK 8500 Maynuo M9712 or M9712C and also the Array 3721A loads. Im in AU Sydney area I can get the BK and Array locally BK8500 $1500 Array 3721A $1200 may be able to do better on the Array? A previous post mentioned the array software is a bit buggy.Any advice or suggestions would be appreciated

author: VK5RC
author_rank: Unknown
timestamp: March 14, 2014, 07:10:04 am
content: On 'fleabay' the 3721 goes for about $900.Regards Rob

author: nctnico
author_rank: Super Contributor
timestamp: March 14, 2014, 11:10:53 am
content: I got mine through Ebay as well. I can sum up the the software which comes with the dummy loads with two words: useless crap.

author: HighVoltage
author_rank: Super Contributor
timestamp: March 14, 2014, 12:03:03 pm
content: I have a BK Precision 8500 and a Maynuo 9811And I can highly recommend any one of those two instruments.Somehow, I like the Maynuo a little more, because it has 2 lines and 4 numbers at the same time in the display.So, watching voltage, current and power at the same time, is sometimes a little benefitAnd the software on both systems works great.For a lower end project, I needed a low cost solution and ended up with several 100 W power resistor, instead of a DC load.Because I did not like the lower cost units at all.

author: Circuitous
author_rank: Unknown
timestamp: March 14, 2014, 01:03:18 pm
content: I have a couple of Array loads, 3723A and 3710A. I like that they can display 4 attributes at once (unlike the BK) but the PC software isn't great and it has a crappy TTL interface (not RS-232 or USB) that requires an adapter (you can make your own).The backlit LCD on the 3723A is clear and bright, easy enough for me to read from 3 feet away. But, I still would prefer a VFD.If I was starting over, I'd probably get the Maynuo. I may pick up a M98xx later this year.

author: MarkL
author_rank: Unknown
timestamp: March 14, 2014, 01:37:12 pm
content: Quote from: Circuitous on March 14, 2014, 01:03:18 pmThe 3723A has an isolated, true RS-232 inteface. No adapter needed.

author: saturation
author_rank: Super Contributor
timestamp: March 14, 2014, 01:56:55 pm
content: Its hard to believe my unit is over 1 year old now, an Array 3710a rebadged as a Tekpower brand. I use it a lot and its saved me a lot of time, grief and burned fingers.I've definitely put it through its paces, often burning at full 200W nearly a day, and the thing never gets hot. The hardware is very well made for what it does and the LCD screen is accurate as displayed; I've checked it many times with DMMs as backup for V and A readouts.The software is poor but functional.Even if you buy direct from China via Taobao.com the Array 3710/1 is typically ~ half - 1/3rd the price of the Maynuo. The build quality of the Maynuo makes me feel uncomfortable but no one has reported failures here; and the software for Maynuo and clones are superior, and has far more functions. You may find the Array 3370/1a sold locally to your country from someone as a rebadged unit so there is less uncertainty buying it Internationally; if Gossen Metrawatt is will to put its name on the Array, it says something for their build quality.https://www.gossenmetrawatt.com/english/produkte/ssl150300.htm

author: saturation
author_rank: Super Contributor
timestamp: March 14, 2014, 02:23:57 pm
content: FWIW, quite a number of Maynuo variants are available from Amazon.com and some sellers ship from USA locally.

author: linux-works
author_rank: Super Contributor
timestamp: March 20, 2014, 07:19:22 pm
content: for interest (and because I took a photo for someone), here is my array box doing a load test of a psu:that array was $700 (sigh). I paid extra for the gpib interface and also to get it from a US seller with a US warranty (in texas, I think that's still the US, lol).it does not go up as high in voltage as I'd want (the Array) but its built pretty well, has a good UI, has ascii SCPI for remote mgmt and uses a simple and easy to get lcd display, so nothing custom or fancy here. rotary wheel is nice and clicky and the front button arrangement is tasteful. I like this box

author: DaGlitch
author_rank: Contributor
timestamp: September 23, 2014, 05:17:46 am
content: Just got a 3721A and was wondering if anyones unit sounds like mine. I can hear the fan just fine, but this sounds like something else. I didn't see any mention of the noise anywhere (or expected it) so I thought I would ask to see if this was normal. Cheers!

author: sacherjj
author_rank: Frequent Contributor
timestamp: September 23, 2014, 01:17:23 pm
content: Quote from: DaGlitch on September 23, 2014, 05:17:46 amThat sounds like maybe a fans running while rubbing on something. The 3710 has two stages of fans, but they come on full, half, off cycle when powering. So it doesn't seems like the sustained sound would be there if it was the fan. Unless the control circuitry is messed up.Although the insides of the 3710 and 3721 might be completely different.

author: MarkL
author_rank: Unknown
timestamp: September 23, 2014, 02:35:34 pm
content: I have a 3723A, which is in the same product line, so I'd expect it to have a similar internal build as the 3721A. The fans are noisy, and they also have the same "rubbing" or buzzing sound as in your video. It's hard to tell, but yours might be a little louder.I would take the cover off and check for anything obvious in the way of the blades. There are two fans, at least in the 3723A, so try disconnecting one at a time to see if one of them is the culprit.Test equipment manufacturers aren't generally looking for the quietest fans when spec'ing their parts. You could always replace them with quieter fans with the same rating if it continues to bother you. It might be a little work getting them out, though, since they're inside the metal air duct around the heat sinks.Or, since it's new, you could ask for a swap for a different unit.(Edit: Fix ambiguity.)

author: saturation
author_rank: Super Contributor
timestamp: September 23, 2014, 06:20:15 pm
content: I think this is a teardown of this model lie from an archived post:https://www.eevblog.com/forum/testgear/any-experience-with-scpi-and-chinese-dcprogrammable-loads/msg352717/#msg352717@ MarkL, is this correct?IIRC, the fans are on continuously in this model line?Quote from: sacherjj on September 23, 2014, 01:17:23 pm

author: DaGlitch
author_rank: Contributor
timestamp: September 23, 2014, 07:25:57 pm
content: Took the unit apart and it is definitely the fans. They aren't rubbing on anything and are just noisy. I can stop both of them and the unit becomes completely silent. Inside my unit:

author: saturation
author_rank: Super Contributor
timestamp: September 23, 2014, 08:37:21 pm
content: Thanks DaGlitch for that photo, it does look like MarkL's teardown device so the other images are from the same model line.

author: MarkL
author_rank: Unknown
timestamp: September 23, 2014, 08:56:48 pm
content: Quote from: saturation on September 23, 2014, 06:20:15 pmYep, that's correct; those are my pictures. Sorry; that's not really much of a teardown. I was mostly answering a question about the built-in isolation.The fans are always on in the 3723A, and they really get cranking if it gets hot while sinking a lot of power.The unit, at least as supplied with the stock fans, is definitely not for those who want it quiet in their lab. It doesn't bother me because there's already so much other stuff running.It might be hard to find a very quiet programmable DC load that can handle a decent amount of power. It has to dump the heat somewhere...

author: Makerman69
author_rank: Newbie
timestamp: July 10, 2015, 04:31:55 pm
content: We've got 8 DC loads made by ARRAY in our lab. Plus more than I can count of their programmable power supplies ( rebadged Circuit Specialists) No problems, they do what we need them to do and then some. Good build quality and terrific value. Can't ask for more. Some of the posts trash these because they are made in China . What isn't made in China? My understanding is that ARRAY is a Taiwan company and the engineering and quality are more on the upper end of made in China products.

author: dolomike
author_rank: Newbie
timestamp: September 14, 2015, 06:05:32 am
content: How well do the Array/Re-branded loads handle a PWM source?We'd like to test out PWM based control circuitry but need something that can handle 5-20kHz PWM signal.Mike

author: forrestc
author_rank: Unknown
timestamp: September 14, 2015, 07:30:03 am
content: Haven't ever put anything like that on mine, what type of wattage, voltage, frequency, filtering, etc. are you planning?My guess is depending on the frequency it probably would work fine. I know on mine (3711A) it seems to have a pretty good sized cap on the input---although I have noticed the ability to get it into oscillations where I have say a constant current source trying to drive it in constant power mode (I think that's the bad combination - if not, you get the idea).-forrest

author: dolomike
author_rank: Newbie
timestamp: September 14, 2015, 03:38:54 pm
content: Well, we normally run DC motors in automotive and heavy duty applications so this isn't a lightweight system. I think we would normally run CC or CR mode for most tests but some could be upwards of 800W. I believe this can be achieved by paralleling the devices in CC or CR mode. Some re-brands state they can be paralleled but I didn't recall seeing anything in the Array manual about it.Voltage: 12V/24V nominal but some tests can be at 28V.Current: ~10-15A but some tests may require almost 30AWattage: Most tests are done at 12V so we could do most of it with ~400W but if the parallel combos work, then we can get up to the ~850W for the extreme tests.PWM Frequency: 5kHz-20kHzFiltering: What type of filtering are you asking about?I guess a lot depends on the current slew rate but the manual states 1mA/us~4A/us on CCH mode which is quite a range so not sure what the driving factor will be.The transient generator can handle up to 50kHz so I would expect it could handle a PWM source upwards of that frequency as well.Thanks for the feedback.Mike

author: nctnico
author_rank: Super Contributor
timestamp: September 14, 2015, 04:20:26 pm
content: I'm not quite sure a standard DC load will do what you want because the control loop will always lag behind and could mess with the control loop of the system you are testing. For this kind of tests I designed & build a switched resistor DC load myself. I can set it to a specific resistance and because its purely resistive it will keep that setting no matter what appears at the input.

author: dolomike
author_rank: Newbie
timestamp: September 14, 2015, 08:16:29 pm
content: It would be more for analyzing performance of some of the power components and PCB in a design and not for testing closed loop control although there isn't much to the loop that would be affected anyway.We do have switched resistance banks but would like to test with a constant current load ideally.Mike

author: rx8pilot
author_rank: Super Contributor
timestamp: September 14, 2015, 08:52:05 pm
content: Quote from: nctnico on September 14, 2015, 04:20:26 pmThat is what I did for my setup. Resistors and capacitors are dumb and predictable. I have an ARRAY DC load, but I am looking at a Chroma mainframe so that I can automate with LABView.

author: LabSpokane
author_rank: Super Contributor
timestamp: September 14, 2015, 10:22:05 pm
content: Quote from: dolomike on September 14, 2015, 03:38:54 pmCould you or someone else explain how a constant resistance / current can simulate a motor load? Not that a electronic load could do much better of a job, but unless you get some sort of a custom wind, typically a power resistor is wound to be non-inductive.

author: dolomike
author_rank: Newbie
timestamp: September 14, 2015, 10:30:04 pm
content: We've looked at the Chroma stuff as well but I don't want to spend over $10k for a 1200W system and probably not use half the features. We aren't looking for pinpoint accuracy since we are using 10's of amps and not worried about mA resolution/accuracy.To help simulate a motor, you do have to add in a comparable inductance. Although you won't ever get the same behaviour as a motor at least you can get it close enough to validate some aspects of the design. The nice thing about the DC load is the transient generator which could help with ripple testing to a certain extent.Another way we have done it is to drive a motor coupled to another and connect that to a load bank.I'd like to have some finer grained control over the load that a switched resistor bank can't easily do especially when operating at varying voltages.Mike

author: nctnico
author_rank: Super Contributor
timestamp: September 14, 2015, 11:22:33 pm
content: Quote from: rx8pilot on September 14, 2015, 08:52:05 pmThat is rather crude. I came up with this (neatly controlled with a microcontroller):

author: rx8pilot
author_rank: Super Contributor
timestamp: September 15, 2015, 12:06:59 am
content: Definitely crude, but I needed it in one day and had to build it from parts on hand. Serves the purpose while being the ugliest piece of gear on the bench by a long shot.Yours looks like its nearly ready for a production run. Nice.Sent from my SAMSUNG-SM-G890A using Tapatalk

author: forrestc
author_rank: Unknown
timestamp: September 15, 2015, 12:40:12 am
content: Quote from: dolomike on September 14, 2015, 03:38:54 pmIn relation to the filtering: I guess I should have asked "are you using PWM to derive DC, or are you using it to drive a motor".My experience is that a DC load doesn't really like a dynamic power source. For instance, to illustrate I hooked my Array load up to my Rigol Power Supply, and set the load to constant resistance mode, and set the rigol to deliver at most 1A at 24V. See the video below to see what happens..... in short the load can't adjust correctly with this type of power source - it keeps trying but it doesn't succeed.(Sorry about the shaky handheld Cell-phone video).

author: dolomike
author_rank: Newbie
timestamp: September 15, 2015, 05:17:07 am
content: We are using PWM to drive a motor - we're not generatingforrestc - Thanks for posting the video as I think it answers my question. It appears that the DC load cannot adjust quickly enough to handle a switching source. Looks like I might have to go for some of the more advanced and thus more expensive models out there.... or I can look at creating a resistive load bank with some smarts like what nctnico has done.I may also play around with an DIY electronic DC load circuit and see what kind of response I can get with it with some high speed component. I wonder what sort of speeds I could get?Mike

author: MarkL
author_rank: Unknown
timestamp: September 16, 2015, 07:25:15 pm
content: Quote from: forrestc on September 15, 2015, 12:40:12 amIt depends on the design of the control loops in both the power supply and load.I tried the same experiment on an ITT MX100TP set for 24V @ 1A, and an Array 3723A load set for 20 ohms. It worked with no instability.While I agree it's hard to beat the simplicity of a real resistor, I wouldn't rule out an electronic load just yet.dolomike: What range of duty cycle for 5kHz-20kHz is needed?In a quick test the above Array settles in about 40us to a 10A target setting. It settles in about 10us to a 1 ohm target setting (@ approx 16A). These numbers are from a simple switch closure, and they're too long for 20kHz, but it might do better with a MOSFET-driven steady state PWM.Edit: Fixed model number.

author: MarkL
author_rank: Unknown
timestamp: September 16, 2015, 09:48:18 pm
content: Here's a little more about applying PWM to an Array 3723A load.A 10kHz square wave was generated by a beefy LIPO 4S battery pack (approx. 16V) put through a MOSFET switch.Here is the load in 10A mode. Blue is current, red is voltage across the load. Until it settles at 10A, it's unreasonably high at almost 65A.Here is the load in 1R mode. For whatever reason, it settles much faster and with much less of a current spike. There's an odd spike in voltage above the idle battery voltage indicating some inductance inside the load.Just for comparison, here is the same plot but with the load disabled. The PWM generator was manually triggered. There's some current being drawn in the beginning due to a capacitor inside the load on the input and likewise, the voltage does not return to 0V because the capacitor is holding it up.So, I think in resistance mode, this load could be usable at 20kHz as long as you know what to expect out of it. Because it overshoots, it's certainly going to stress your circuit for testing.You'll have to be the judge. Maybe it's worth a try. No idea on the parallel requirement, though. I only have one.Edit: Fixed model number.

author: SharpEars
author_rank: Unknown
timestamp: October 07, 2015, 11:51:15 pm
content: Quote from: MarkL on September 16, 2015, 09:48:18 pmAs far as I can tell, there is no such thing as an Array 3732A load. What is the correct part number?

author: rx8pilot
author_rank: Super Contributor
timestamp: October 08, 2015, 12:15:57 am
content: I have a 3710A - looks like the one in the video a few posts back.incidentally, it's for sale if anyone needs one.

author: Circuitous
author_rank: Unknown
timestamp: October 08, 2015, 01:04:27 am
content: Quote from: SharpEars on October 07, 2015, 11:51:15 pmWell, I have an Array 3732A, it works quite well. I got it from here:http://www.circuitspecialists.com/array-3723a-electronic-load.html

author: MarkL
author_rank: Unknown
timestamp: October 08, 2015, 02:44:49 am
content: Quote from: SharpEars on October 07, 2015, 11:51:15 pmOops - sorry. It's a 3723A.

author: Makerman69
author_rank: Newbie
timestamp: February 22, 2016, 06:17:51 pm
content: We use several ARRAY products including three different models of their DC loads at our test facility. Can't say anything bad about them and there is significant cost saving compared to so called legacy brands. My understanding is this is a Taiwanese company manufacturing in China. Maybe the engineering is a bit on the upside compared to some of the mainland China makers.

author: Zbig
author_rank: Frequent Contributor
timestamp: September 07, 2016, 09:49:08 am
content: I've just got an ARRAY 3721A. I'm quite impressed with it so far but I'm a bit surprised by one design decision. Peeking under the heatsink assembly, I could see eight pass transistors in what looks like a TO220 packages to me. Granted, the heatsink is beefy, there are two fans and the airflow is tunneled within a metal sheet shield but isn't asking the poor TO220s to dissipate 50W each maximum (the unit is rated 400W) stretching it a bit? I'm pretty sure they knew well what they were doing but still, why not TO247?I could imagine the thermal compound going bad on one of them and the heatsink-mounted temperature sensor not even noticing as the localized hot spot from a single TO220 wouldn't affect the average heatsink temperature much. Or am I overthinking it?I realized the last sentence didn't make much sense but anyway, seems quite strange to use TO220 in such device.

author: forrestc
author_rank: Unknown
timestamp: September 08, 2016, 06:58:41 am
content: Quote from: Zbig on September 07, 2016, 09:49:08 amI just picked a random FET datasheet with TO-220 and TO-247 options. This one has 0.45*C/W junction-case thermal resistance listed for TO-220, TO-247 and D2PAK. So, for heatsinked applications, it seems like it should be good (50W *0.45C/W = 22.5*C temperature rise, with a 175*C junction temperature max means the case needs to stay under 152.5*C)... So, this doesn't seem like a lot of a stretch. One would have to look at the thermals for the exact transistors and also the thermal resistance of the heatsink (case to ambient).

author: Zbig
author_rank: Frequent Contributor
timestamp: September 08, 2016, 07:07:59 am
content: Thanks for checking that. Actually, it's case to heatsink resistance I'm more worried about. Do they specify that as well for the one you've checked?

author: nctnico
author_rank: Super Contributor
timestamp: September 08, 2016, 09:33:56 am
content: IIRC you have to count on 0.5C/W for direct heatsink mounting (non isolated) when it comes to a TO220. After that you have to add the thermal resistance of the heatsink which can be another 0.5C/W even with air cooling. All in all that 50W easely adds up to a 75 degree C difference between the air and the die of the transistor.

author: Jester
author_rank: Frequent Contributor
timestamp: September 08, 2016, 02:18:58 pm
content: Quote from: MikeO on September 06, 2012, 06:02:16 amFWIW, I have a couple of old school Kikusui loads (PLZ72W and PLZ152WA), still working fine.The one thing I really like about this old school equipment is the ease of use. Much like my go to Agilent E3615A power supply, you turn it on and adjust to the desired value. I had and sold an Array power supply nearly identical to the Array load being discussed, it worked very well functionally however the user interface sucked. The loud beep on every key touch was also annoying until I put a piece of tape over the transducer.The one thing I did not like about the PL72W was the single line display, so I replaced it with a cheapo but accurate ebay dual V/I display that fits in the original cutout.

author: Peter_O
author_rank: Frequent Contributor
timestamp: March 29, 2022, 01:12:26 pm
content: I've a 3710 electronic load and just got the 3312 USB adaptor 2nd hand.Simple and maybe stupid question: Do I need the 9male-9male cable null modem or 1:1?

author: OiD
author_rank: Regular Contributor
timestamp: September 01, 2024, 06:54:53 pm
content: Guess I'm going to do some necromancy here in this old topic.I was doing some maintenance on my Array 3710A and did a complete tear-down. I solved the issue of bad voltage measurements by adding dome shaped washers.I'm very happy with it, got it back around 2014 for 80€ when a company I worked at shutdown.I've been looking at tear-downs of the 3711A and... they are identical. I have often run mine at 200W continuously and had no issues. Any higher than that and it disconnects the load.So if the schematics are identical... and so is the actual device...Is it only software that is limiting the power?I think I saw an EEPROM next to the MCU, I doubt the actual code is stored there, even the 150W or 300W keyword... but maybe we could do EEPROM dumps of the devices and see if there is anything?If anyone has the schematics for the 3710A and 3711A and they are correct/identical...Doubt I'll have time to dump my EEPROM in the coming weeks as it's in use.

author: jacky1975
author_rank: Newbie
timestamp: June 25, 2025, 03:31:56 am
content: Array 3710 can use Array 3711 software to adjust to 300W load.

author: neverendingstudent
author_rank: Regular Contributor
timestamp: June 25, 2025, 04:03:31 am
content: I have a number of Array / Circuit Specialists 3710A electronic loads I got from a pallet of T&M gear I won at auction - I've been cleaning / testing / selling them one at a time on eBay. They are pretty nice and, at least according to the specs, designed to be pretty hard to accidentally damage. Over current / over voltage / over power protection, reverse polarity protection. The 3710A is rated for 150W and I've tested them up to the 190W range when stress testing before eBay sale and they've held up fine.With all that said, I also have a bunch of rather nice Japanese Kikusui PLZ334W loads... feel free to guess which ones I keep to use on my personal bench.

author: MathWizard
author_rank: Super Contributor
timestamp: June 29, 2025, 09:41:56 pm
content: So I've been modelling and modding the Array3700 (maybe it's 3710), for now to use 8x IRFZ44N, so I'll only go up to say 40V max (they are from ebay too so I don't exactly trust their ratings).For now, at least with 40V, I think I can make a version that goes up to about 150W continuous, and I figured I'd double it to 300W for really short tests or pulsed loads, I better calculate if the junction temp is still ok.One thing I see is in this Array3700, is a lot of capacitance around the control loop. So like on the main Vref input , and on the voltage control op-amp for all the mosfet driver op-amps, and again on the output itself, they have chosen large caps.So doesn't that really limit the testing it can do ? With all the caps removed or greatly reduced, the gain of the main voltage driver drops to 0dBV at 1MHz. With those caps in the pdf, the main voltage driver is 0dBV by 100Hz. In both cases the DC gain is up around 70dBV with the OP07's and a mod or 2 I've made.I have tons of little switches, so it wouldn't be hard to low and high bandwidth setting. IDK how fast high current DUT's can respond tho, so maybe you don't want to try changing the load too fast.But don't people hook up their signal gen's to E-load and do all kinds of HF stuff too ?