Does a hobbyist need a bench power supply? - Page 1
Forum section: electronics / general

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 13, 2010, 01:12:28 pm
content: So, all these projects we are making all require power, so an essential piece of equipment is something to power all of these.My first power supply was an Irwin variac power supply, which provided AC and smoothed, unregulated DC. I got it from a skip at school as the plastic casing was smashed and the banana plug sockets damaged. I then found it also had a 110V winding which meant you could get twice as much output voltage. It served me well until my dad chucked it out in a clear up whilst at uni.Since then I have relied on wall-warts (for most digital/microprocessor based work), custom built (e.g. +/- supplies for amplifiers), and a single-ended programmable switch mode bench supply (a GWInstek PSP-2010http://www.gwinstek.com/en/product/productdetail.aspx?pid=38&mid=75&id=164which I got because it was £100 in clearance at Rapid, and is very useful for battery charging, testing motors and so on).I'm feeling the need to get a proper bench power supply now - but I'm not quite sure why. Maybe it's because I see them on everyone else's bench. Maybe I'm just annoyed at having to build a 1.2/3.3/5/12/15V power supply each time I need one.So what to people feel they need in a bench power supply? Is dual output with independent/parallel/series enough? Do we even really need a variable power supply for most projects? How much current is enough?I've been looking at these two:http://cpc.farnell.com/caltek/psm3-5a/power-supply-bench-led-3ch-30v/dp/IN05511- which is mentioned here:http://www.rcgroups.com/forums/showthread.php?t=1030827http://aspen-instek.com/01-multi-output-dc-ps.html(GSP-4303 - I've bought from these guys before, their prices are very good).Any thoughts? Any bargains knocking around?

author: Unknown
author_rank: Unknown
timestamp: June 13, 2010, 02:12:44 pm
content: In my opinion, yes. It's used to power something before the power supply is finished, and to independently test the modules. Or just for experiments.I use the variable current limit to set the current limit just barely above the normal current draw, so nothing blows up when shorted. The variable voltage is useful to test things like minimum voltage (eg. dropout voltage of a regulator). There have been various topics on this forum about them. You can also build one yourself, they're not that complex.Tracking is useful for op-amps which need symmetrical power supplies. Amount of current depends on your projects, I rarely use more than a few hundred milliamps, but I also know people that have and use 10A+ power supplies.

author: Zed
author_rank: Contributor
timestamp: June 13, 2010, 03:43:20 pm
content: I would say that a variable voltage power supply is one of the things you need after a multimeter but don't bother buying one, build your own. My bench power supply is based on a LM317 variable voltage regulator, will supply current up to 1.5 amps but it only has a 1 amp current meter and best of all the voltage is variable from 1.2 volts to 13 volts which is pretty much all you need for doing hobby electronics. If you need current limiting, which is handy, you can use a L200 voltage regulator which will go up to 2 amps but the voltage will only go down to 2.85 volts. My next power supply project will prolly include + and - fixed regulators of various voltages for op amp work as well as the variable supply. The internet is awash with schematics and data sheets so you can easily find a design to suit your needs.

author: charliex
author_rank: Frequent Contributor
timestamp: June 13, 2010, 06:05:10 pm
content: i'd say fairly essential, primarily for the reasons before, variable and current limiting.less useful is the atx to bench conversion, since its neither of thosehttp://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply

author: XynxNet
author_rank: Regular Contributor
timestamp: June 13, 2010, 06:27:11 pm
content: For me a bench power supply is essential. I don't need variable current, but variable voltage is a must have.I don't think it would be a good idea for a beginner to build one himself. Mains is just too dangerous, if you don't really know what you are doing. Fortunatly simple bench power supplies arn't that expensive anymore.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 13, 2010, 09:39:49 pm
content: I need it all ... variable current ... variable voltage 10A to 30V, so to be able to test anything .My advice , get the best , its the only tool that you will own it for a life time..The ones with variable current are immortal

author: PeterG
author_rank: Frequent Contributor
timestamp: June 14, 2010, 03:20:45 am
content: I use 2 power supplies. The main ps is a standard 0-30V 0-5A setup. The other is a 9-15V 30A unit.I would be lost without either of them.RegardsPeter

author: MrPlacid
author_rank: Frequent Contributor
timestamp: June 14, 2010, 04:24:49 am
content: As a hobbyist myself, I can see the vital importance of a bench power supply. It just makes life simpler and testing ideas much quicker. I just bought my first 0-18V 5A power supply last month and I am already searching for one with higher voltage of 50V and up. Not only can I run test circuits of it, I can also run other consumer equipments too.Depending on what you are using it for, you'll require different voltages. For auto 12v, phone 48v, airplane parts 28v, etc..The bench power supply has so much uses. We can even uses it to blow up capacitors (and fuses) just like Dave

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 14, 2010, 04:32:43 am
content: You can almost never have too many power supplies, and at least one or two should be adjustable with current limit. Fortunately, they're extremely easy to build, especially with all the buck converter chips out there.

author: cksa
author_rank: Regular Contributor
timestamp: June 14, 2010, 05:57:16 am
content: What are some popular buck converters with adjustable current limit?

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 14, 2010, 08:35:52 am
content: To all those that feel the self-built is the best route to go - can a home built supply even compete on cost with a bought one? There's quite a few high value parts in there:* Transformer* Case* Smoothing caps* Heatsinks* Panel metersI just remember the first audio amp I built from a kit (I think it was 150W or so)- the kit itself cost about £50, built and tested at school using a bench power supply. Then I came to casing it, and found that mains lead, fuse, power switch, grommets, terminals, phones all cost a fair bit. Then there was the power supply... cost an absolute fortune!

author: saturation
author_rank: Super Contributor
timestamp: June 14, 2010, 12:28:51 pm
content: I couldn't agree more. Unless your parts are salvaged from the trash, building won't be cost effective if premade assembled or a kit exists. You can buy cheaply if you get a brand like Mastech. At the very least, you get the hardware you can modify to improve the specs or repair, if necessary.The reason is economy of scale, inventory and distribution chain. DIY is a 'custom build.' By the time DIY new parts you need reach your distributor, and finally you, its gone through several hands that up the price, not to mention shipping, handing, taxes or duties.Engineers dedicate careers designing power supplies especially in this Energy Star conscious world. Why reinvent a well established wheel except for the fun of it?That said when I consider the simple general specs:linear or switchingone, two or > 3 outputsprogrammableThe unit you already have is more than necessary for most home lab work, but do you need more than one ouput? With the ever increasing trend to low voltage, low power usage in devices, especially made to be portable and battery powered, a clear need is one with tight dependable regulation, and constant fully adjustable V and I.Quote from: cybergibbons on June 14, 2010, 08:35:52 am

author: cksa
author_rank: Regular Contributor
timestamp: June 14, 2010, 12:44:31 pm
content: Well you could just get a cheap not adjustable power supply, say that supplies 5 amps at 12V. Then you do all your DIY stuff after that. Shouldn't be too expensive?

author: Unknown
author_rank: Unknown
timestamp: June 14, 2010, 02:23:29 pm
content: You can often get some of the parts cheap, like transformers, heat sinks and a case. If this is the case, DIY might be cheaper. Or if you want more advanced features, since commercial power supplies with features like GPIB/RS-232/LAN control get expensive fast, but it might only add $15 or so to your build costs. If you pay full retail, everything gets expensive.Cheap lab supplies aren't usually very energy efficient, just simple linear supplies with at best a switchable second transformer winding, so I doubt that the designers spent a lot of time on that. When set to 10% of the max. output voltage, 90% of the power will be converted to heat, regardless of what you do.I agree that high currents and high voltages are a lot less important for most modern devices. It's more important that you can accurately output something like 1.2 or 0.8V than 2x30V. But it depends on your applications.

author: Rhythmtech
author_rank: Regular Contributor
timestamp: June 14, 2010, 03:06:10 pm
content: I added an LM317 to my ATX conversion bench top. I can get variable output from 2V - 12V and from 12V - ~23V. The amount of current I can use depends on the voltage drop across the regulator, but I usually get the 300 - 500 mA I need for most small projects. I have a large adjustable supply from Sorensen if I need more, but I rarely do. The small size of the ATX power supply in my work area, the fact it didn't go in the trash and that I built it make it a tool I reach for often.I have been considering adding a buck boost regulator to raise voltage out on it, but only for fun since the majority of my projects are all TTL level. I did a cursory check on digikey and came up with anAP34063, which for 76 cents did not seem bad, but would require a bit of work since it seems to rely on capacitance to change switching frequency to adjust the output. It would be nice to have a switched output instead of the linear also, so as to not worry about frying the regulator as I sometimes get close to doing on the LM317 when I run it at 3.3V. So I am still on the lookout for a cheap buck boost solution. I also would like add a voltage readout(s) eventually.

author: saturation
author_rank: Super Contributor
timestamp: June 14, 2010, 03:10:18 pm
content: http://mastechpowersupply.com/dc-power-supply/linear-power-supply/mastech-regulated-variable-dc-power-supply-gps-3030d-30v-3a/prod_62.htmlJust checking, they have over 50% discount on their PS. This wasn't there in the winter, when I first took a look at their linear and switched supplies.

author: slburris
author_rank: Frequent Contributor
timestamp: June 14, 2010, 03:52:16 pm
content: So their sale price is $90 for a 0-30V 0-3amp supply.For about $170, what do you think about their 3 output supply:http://mastechpowersupply.com/dc-power-supply/linear-power-supply/mastech-linear-dc-power-supply-30v-3a-hy3003f-3-triple-outputs/prod_7.htmlLooks like two of the $90 supplies put together with a 5v supply thrown infor less than 2X the cost.Scott

author: Rhythmtech
author_rank: Regular Contributor
timestamp: June 14, 2010, 04:30:19 pm
content: I can't seem to recall what the requirements of the power supply we are supposed to recommend are? Personally I kind of likethe programmable one. It's small so it won't take up too much space, allows you a measure of automation via a PC as well as apparently an arbitrary waveform generator.Upon looking for any information regarding the interface via manuals etc... I came to find that, none were available through mastech's site for any of the DC power supplies. At this point I would pay more to get a product with some support other than a pamphlet of unknown quality. The support button takes you to a link to their forum, where the only thing you find regarding the programmable power supply is posts telling everybody it is new.Do yourself a favor and get a PS that at least has manuals posted online so you can check out how crappy the instruction are in advance and get a feel for how important the company feels you are. I had an Extech EX330 meter that broke and was shipped a replacement within a week, their customer service was excellent in my experience.Check this one out -Extech 382213$199.99Here's Extech's page with manuals and a data sheetWay better than mastech's "support forum".

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 14, 2010, 04:49:35 pm
content: Interesting discussion!I agree that my programmable 20V/10A supply is enough most of the time. It's switch mode so quite efficient. I certainly couldn't use it as a arbitrary waveform generator though, as RS232 is just too slow.I'm also a big fan of manuals and support, which I guess is why I have a GWInstek scope and not a Rigol... but then I could have bought two scopes for the same price.That said, power supplies are a lot more simple.

author: slburris
author_rank: Frequent Contributor
timestamp: June 14, 2010, 05:28:04 pm
content: I'm glad I'm not the only one having trouble finding Mastech manuals online.But seriously, a Quakko power supply? I'm still smiling at the name. Aren'tthey another brand of Aoyue? I've heard of them only in the context ofSMD rework stations.Personally, I tend to prefer the LED displays over the LCD -- easierfor my eyes to read :-) If money were no object, I like theHameg 7044:http://www.hameg.com/163.0.htmlBut we're outside of what most hobbyists need, including me!I suppose it's too much to ask for a power supply manual to containschematics these days (the Extech manual does not).Scott

author: Unknown
author_rank: Unknown
timestamp: June 14, 2010, 05:31:13 pm
content: Get a used one (eg. HP) from ebay. You'll probably be able to find a schematic for those, certainly brand names like HP. Except for switchers and digital control, I'm not aware of many improvements in bench supplies in the last fourty years or so, so an old one with analog panel meters might work just as well (I actually prefer analog panel meters, they have a much higher bandwidth and I don't expect accuracy anyway).

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 14, 2010, 05:40:01 pm
content: I do like the way that HP test equipment, no matter how complex, always had the schematic. It amazes me what they managed to do without microprocessors.Hakko is another brand that sounds like Quakko... maybe this is the first case of a clone of a clone company?I agree with the LED over LCD - my current supply has an LCD display which can't be read from above at all, which is really irritating.For some reason the UK has a very poor second hand supply of power supplies on ebay. Most of my finds have been from skips... I used to have several lovely valve scopes as a result.

author: allanw
author_rank: Frequent Contributor
timestamp: June 14, 2010, 06:13:46 pm
content: I bought a used TTI PL330QMD dual output 30V/3A supply off ebay for only $50! The only downside was that it was wired for UK power, but the manual actually gave steps to convert it.The current limit on one of the outputs was abnormally low, so I asked the manufacturer for a service manual and they actually gave me one. Turns out the problem was just some burnt out resistors, which I'll be replacing soon.

author: Rhythmtech
author_rank: Regular Contributor
timestamp: June 14, 2010, 06:34:36 pm
content: Quote from: cybergibbons on June 14, 2010, 05:40:01 pmNot the first case for hakko -Luckey 936I've always had most of the ps's I've used at eye level mounted high on the bench, so I had not considered the LCD vs. LED issue. At home it would probably be much lower and I will definitely consider it from here on out.I bought a used Sorensen industrial variable DC power supply from ebay and have had to do some repairs as it was in an industrial environment. But I can't complain about getting a $1200 power supply for $30 shipped. It is not really a bench supply however, weighs about 35 lbs and is cumbersome because of its size on small benches. Eventually it may become part of a home test and measurement test board setup.For my day to day small power needs I built an ATX conversion power supply out a 350W Antec power supply because I wanted a supply I could carry to meet ups, give to a budding techie if I wanted to at no great loss, or blow up without much concern. I had all the parts sitting around already and it was a good excuse to "clean up" productively. I would however prefer to eventually get a good bench supply, but my current setup allows me to more than get by so I am happy at the moment.I like this -Extech 382280too much $$$ for me though.

author: saturation
author_rank: Super Contributor
timestamp: June 14, 2010, 06:53:28 pm
content: Yes, what's I see most work put in by designers is evolving PSU programmable modes, tighter parts integration, improved efficiencies and regulation. These Mastech's have ~ volts and amp ratings, but the regulation is 2-10x worse on the SPSU. At this price range, I'd be probably thinking of a better cost effective brand name, like Instek. Consider too, the LPSU is 25#, while the linear is 10#.http://www.mastechpowersupply.com/dc-power-supply/linear-power-supply/mastech-variable-linear-power-supply-30v-10a-hy3010d/prod_11.htmlhttp://www.mastechpowersupply.com/dc-power-supply/switching-power-supply/mastech-power-supply-hy3010ex-30v-10a-over-voltage-over-current-protection/prod_70.htmlSo what does a small lab need?More than anything else, I think an a priori in electronics is a PSU with clean stable output power. NiMH cells provide a low cost portable power supply, and typically output 1.2V at 2700mAH. They need to be cutoff ~ 0.9V. So, a PSU in the 0-15 3A works very well to emulate single cells to 14 NiMH cell packs, at least in my application. Also, most analog and digital components easily work in this voltage range and power requirement.In this application, a modest linear can provide a home lab user an easy to repair, quality PSU so a brand name is less critical. This smaller Mastech seems just right, but because this device is seems well suited doesn't make the whole Mastech lineup equally outstanding. Mastech documentation isn't widely available on the net. Some schematics are here:http://www.eserviceinfo.com/equipment_mfg/Mastech_11.htmlA simple example:Mastech HY1503D is $50, 0-15V 0-3AMastech is also sold as the Kaito brand, and there have been some complaints in the high current output devices on Amazon. I also would not trust its programmable models, given the need for good documentation and support in that area and would easy go form Instek.Quote from: alm on June 14, 2010, 02:23:29 pm

author: Rhythmtech
author_rank: Regular Contributor
timestamp: June 14, 2010, 07:28:28 pm
content: Quote from: slburris on June 14, 2010, 05:28:04 pmIf you look at the Quakko model number it is very similar to all of Mastech's power supply products, I don't know who the ultimate manufacturer might have actually been. Seems like Rebranding clones is becoming more lucrative than counterfits are. This is worrisome as I don't believe people are unknowingly buying fakes anymore.

author: saturation
author_rank: Super Contributor
timestamp: June 14, 2010, 07:45:24 pm
content: It reads good, but consider its size and weight when it occupies your bench. At those requirements I get confused between going to the switching supply camp. I should have added that choice to my example:http://www.mastechpowersupply.com/dc-power-supply/linear-power-supply/mastech-variable-linear-power-supply-30v-10a-hy3010d/prod_11.htmlhttp://www.mastechpowersupply.com/dc-power-supply/switching-power-supply/mastech-power-supply-hy3010ex-30v-10a-over-voltage-over-current-protection/prod_70.htmlQuote from: slburris on June 14, 2010, 03:52:16 pm

author: saturation
author_rank: Super Contributor
timestamp: June 14, 2010, 07:46:41 pm
content: Yes, I think there are other brand names as well. Here's the parent website, it looks like their principle is Mastech.http://www.mastech.com.cn/html/en/products-dc-1.htmA good news for skeptics, Instek's low end linear look like rebadged or upgraded Mastech, including the same model numbers, so one could say Instek's management has some faith in this product line:http://www.gwinstek.com/en/product/productdetail.aspx?pid=38&mid=53&id=128Quote from: Rhythmtech on June 14, 2010, 07:28:28 pm

author: Rhythmtech
author_rank: Regular Contributor
timestamp: June 14, 2010, 08:29:39 pm
content: Instek may impose their quality control standards on the product line which they sell under their name, which would be good. Sometimes, this is not transferred to the manufacturer's QC though for products manufactured under their brand. So even if it is the same product it does not mean that their are equal.Given it is the low end they are probably the same units since additional development cost would probably negate the production costs savings. Presumably they have tested the unit to verify it is up to their spec. Assuming Mastech's is not a complete piece of junk is fair. Although, buying Mastech then using GWInstek's support infrastructure to save a couple bucks would not sit well with me. I need my equipment manufacturer's to be there for me when I need them to be and not out of business or without documentation to remain competitive.

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 14, 2010, 08:45:59 pm
content: The re-branding thing gets deeply confusing. You're never quite sure if something with the same specs and front panel is actually the same beneath the skin, or just someone very, very good at copying a product. We got some DeWalt cordless power tools from the Far East once, and even the cast aluminium parts were spot on - the only problem was the cheap gear boxes, motors and batteries!For example, Farnell sells a number of different items as "Tenma". Sometimes they actually re-badge them (both physically and in manuals), other times they just sell the original brand - loads of Tenma multimeters are just Uni-T ones. It's quite weird.

author: Rhythmtech
author_rank: Regular Contributor
timestamp: June 14, 2010, 09:53:08 pm
content: Quote from: cybergibbons on June 14, 2010, 08:45:59 pmMany clone products are made on the same equipment as the originals. Discarded dies, molds, etc... are copied or repaired and reused. I can imaging sloppy gears coming from worn dies out of spec. I've heard more than one story of the great savings of chinese die manufacturers as they recoup profits by making a second set of your dies without letting you know, then selling them down the street. Ghost shifts runs can be on the same equipment the originals were currently being manufactured on save for the quality control on materials used to manufacture the parts or cheaper filler blended or substituted.Here's a great story -BunnieStudios Chumby On microSD ProblemsOkay to unhijack the thread....I think defining how the power supply will be used will tell us what we need.For me, I rarely ever run in to an instance of needing more than +/- 15V at more then 2 amps for the electronics I assemble as prototypes. This solidly puts me in the middle of the voltage/current range. Servos, stepper motors, nixie tube power and the like generally I would either purchase a powered control or build a separate power circuit. I would like programmable capabilities, because I enjoy integrating equipment and turning multiple systems into one. Regulation is usually obtained by a linear regulator on my finished circuits with regulators like aLM7805orLM317, so any bench power supply with regulation of ~0.1% is good enough, which most Mastechs we've looked at do ~0.01%. I probably will only use it 1 to 10 times a week for 1 - 4 hours each time, and nobody will lose thousands of dollars for ever minute it is down if it breaks, so a Mastech would probably fit my needs well enough for everything I am going to want to use it for.

author: saturation
author_rank: Super Contributor
timestamp: June 14, 2010, 10:16:57 pm
content: Yet another 'clone':Quote from: saturation on June 14, 2010, 07:46:41 pm

author: comox
author_rank: Regular Contributor
timestamp: June 15, 2010, 11:49:50 am
content: I'm an IT professional by trade, and an electronics hobbyist by, um, hobby... I'm also weird as I have 4 benchtop PSUs:1x TTi 302T triple-output bench top power supply (backup, in closet)2x TTi laboratory-grade QL355TP bench top power supplies. Yup 2 of ‘em.1x Agilent 6811b AC power supply and analyzer, which I control from a PC using a USB-to-GPIB adapter.The Agilent 6811b is a dangerous piece of kit and produces deadly voltage levels, but I use it all the time as I work with AC and power supplies. In fairness, the Agilent 6811b is on the floor.The QL355TP is a great, but produces some fan noise. I love the TTI power supplies, and I believe that they are made in Britain.Proper bench top PSUs will give you control over both voltage and current, which can be handy during the design phase. For example, let’s say you are designing a circuit that you wish to power from a battery. During the design phase, you would dial in the voltage and power limits of the battery into the PSU as to ensure that your circuit will operate within the power limits of the chosen battery. A PSU with current control would allow you to limit the amount of power available to the circuit under development allowing you to ensure that power is not exceeded. A good PSU would display in real time the current being consumed by the circuit. All good stuff.

author: logictom
author_rank: Unknown
timestamp: June 15, 2010, 02:58:07 pm
content: I still need to either buy or build a power supply, I keep changing my mind if I should buy or build.The main thing putting me off building is finding a good case and making the thing look half decent. Whilst buying a supply is less educational, you get less control over the specs and for anything with more than one output they seem to be £120+This is the most reasonable single output one I can findhttp://www.maplin.co.uk/Module.aspx?ModuleNo=219129&j=truethe rather limiteddatasheetbut is it cheap because it's a load of garbage?

author: Time
author_rank: Frequent Contributor
timestamp: June 15, 2010, 04:23:28 pm
content: Quote from: comox on June 15, 2010, 11:49:50 amYou must be a very successful IT professional to own a serious piece of equipment like this for hobby reasons.

author: slburris
author_rank: Frequent Contributor
timestamp: June 15, 2010, 06:23:40 pm
content: So I asked support@mastechpowersupply.com for a schematic of the HY3003F-3.They didn't have that, but sent me a schematic of the next one up in the series,the HY3005-3. I haven't studied it in great detail yet, but it give me hope I couldrepair one of these if I decide to purchase it.Note that mastechpowersupply.com is a US distributer, Acifica, Inc.Scott

author: saturation
author_rank: Super Contributor
timestamp: June 15, 2010, 06:36:28 pm
content: I have a link below with additional schematics, they look pretty standard, for those in the linear range.More importantly, I've also canvassed Amazon feedback from those who have purchased Mastech PSU, and most have been favorable. Some comments on build quality, only one had a major failure. Their forum posts may be misleading about quality, since most posts are about tech support issues and complaints, so posts are about damaged units.I sent a email to them inquring too about schematics and user manuals and pdf, and response was prompt, within the hour, but nothing to send.Last item I found is their eBay pages:http://reviews.ebay.com/Mastech-Power-Supply_W0QQugidZ10000000008864448He has a good rep.Quote from: slburris on June 15, 2010, 06:23:40 pm

author: saturation
author_rank: Super Contributor
timestamp: June 15, 2010, 06:40:50 pm
content: Nice stuff. I like your enthusiasm! Care to share why you have 4 bench supplies?Quote from: comox on June 15, 2010, 11:49:50 am

author: comox
author_rank: Regular Contributor
timestamp: June 15, 2010, 08:57:20 pm
content: I bought the TTi el302tv back in 2007 new for £305 (British pounds, excluding VAT) when I first started playing around with microprocessors. It is a nice unit, and good for the bench as it has NO fan noise. However, the analogue dials are easy to bump and thus knock the voltage and/or current limits askew.I bought the first TTi QL355TP 2 years later, second-hand on eBay (UK) for £530, ex VAT. I was after a more precise power supply as I was experimenting with charger designs (e.g. phone charger, gadget charger) at the time. This is a great unit, but produces fan noise. No risk of knocking the power or current limit settings as it is digital. This is now my daily use benchtop PSU and the el302tv is in the closet.I bought the second TTi QL355TP a couple months later for TTi directly, ex demo, for £478.50, ex VAT. Funny that: was cheaper than eBay, and was in brand-new condition. I bought it because I am weird and need things I like in 2s. Not kidding: when I grocery shop, I never buy one of something I like. Kind of like Obsessive Compulsive Disorder, but stops it at 2. However, I would like to point out that I have only 1 handheld multimeter, unlike our esteemed video blogging host!There is no reason that I needed the second QL355TP. I was sent an ex-demo salesheet from TTi and phoned them to purchase an ex-demo LD300 DC electronic load. It was sold already so I purchased the QL355TP instead. As I said, I am weird.I purchased the Agilent 6811b back in Feb this year as I have been doing a lot of work with AC power switching. I have been working on a zero-crossing detection circuit for actuating a relay when the AC voltage crosses the zero threshold. I needed to produce a design that would work "around the world" regardless of line voltage (e.g. 110V US, or 250V in Europe) or line frequency (e.g. 60Hz US or 50Hz Europe) and I therefore needed a special power supply that could output AC voltage at different frequencies. The 6811b was the answer, and I found a second-hand one on eBay for £1455 ex VAT. brand new would have been at least £4000. Had to splurge on an Agilent USB-to-GPIB adapter to control it with the PC, but was worth it. This is a very cool product, but very dangerous due to the high voltages produced. Did you know that AC in aircraft operates at 400Hz?I have been in IT for 20 years, and am burned out with pushing bits around. I am the same age as Dave and my original love was always electronics. I re-discovered electronics a few years back, and have put my heart into it. Dave's videos fill in the theory that I missed a) not studying electronics at uni, and b) not doing it for a living.I would recommend the Thurlby Thandar (TTi) kit to anyone, as I think it is well engineered. And heck, it is made in Britain!Comox

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 16, 2010, 07:05:58 am
content: I've used very similar Agilent gear for testing products to see if they will deal with different voltages and frequencies. Also you can produce glitches and the like, for simulating generator power, or if you are testing a UPS. If I remember correctly it has fairly good control of limits so you can't really break anything by just spinning a dial...The power in aircraft is 400Hz because you can reduce the size of inductors and transformers I believe.Anyway, I managed to pick up a GPS-4303 for not much more than the cheap Caltek supply... it seemed like a pricing error at first, but called up, and it isn't ex-demo or anything. Seems like a nice bit of kit - the design does look v. similar to the Caltek shown on rcgroups.com but the construction standard appears to be higher.

author: saturation
author_rank: Super Contributor
timestamp: June 16, 2010, 11:43:04 pm
content: A nice unit, CG, and another Instek. Did you have a particular need for this type of power, or was it just a good unit for price? It ranges in the $400 US.The manual is at tequipment, and it reads impressively for a 7kg unit. Its not explicit but it reads like a switching power supply but with regulation and ripple to rival the best linear supplies.Quote from: cybergibbons on June 16, 2010, 07:05:58 am

author: saturation
author_rank: Super Contributor
timestamp: June 16, 2010, 11:46:27 pm
content: A fun story, pretty much in the vein of a lot of enthusiasm here. I'm sure if you have rechargeable batteries around, they are getting well topped upQuote from: comox on June 15, 2010, 08:57:20 pm

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 17, 2010, 12:49:52 am
content: With all this digits on display , I got excited ...I have the Kenwood PD3510 laboratory-grade PSU , is there any worthy solutions , so to replace the analog voltage meter , with digits . (4 or 5 digits resolution)I could glue on it the Fluke 87-5, but I am looking for an "true good" alternative solution.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 17, 2010, 05:45:37 am
content: Quote from: cybergibbons on June 14, 2010, 08:35:52 amSurplus/recycled parts can really lower the cost. Especially if your application needs a supply similar to a mass market unit like ATX power supplies. And really oddball power supplies would be cheaper to build.

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 17, 2010, 06:54:55 am
content: Quote from: saturation on June 16, 2010, 11:43:04 pmAfter all of the earlier posts, I was looking for a bench power supply - the RF transmitter/receiver project I am on at the moment needs two independent voltages, one of which I need to vary from 1-12V. It was just cheaper than any other dual rail power supply so I went for it. I can't remember how many 5V wall warts I've frazzled now as well (I have maybe 30 in a box, all old phone chargers).I do have to admit, I'm pretty happy with it - it seems to perform well. It works up to about 32V/3.2A on each channel. Maybe my only complaint is the single output on/off button - though it does make a satisfying series of clicks as all 4 sets of relays come in and out. I may even try it with a powerful audio amp to see how it copes!

author: saturation
author_rank: Super Contributor
timestamp: June 17, 2010, 05:32:40 pm
content: If you are ever inclined to dissect it and see how its made inside, I'd be interested in the quality of their engineering.Quote from: cybergibbons on June 17, 2010, 06:54:55 am

author: Hypernova
author_rank: Unknown
timestamp: June 18, 2010, 01:53:14 am
content: Am I correct to assume that thisAtten APS3005S-3Dis just a superficially touched upMastech HY3005F-3?They appear to have the same spec too except that the Atten is nearly 5Kg lighter ?And what does Atten mean by this line in their spec?Series Parallel Working Method:-series adjustable rate: ?300mVWould be odd if it means the combined error in series since it's far larger than the independent errors combined.In Aus the Atten is $70 cheaper than the Mastech so I'm thinking about it given my low budget. I need something that's good for 5A@24V for sure.

author: saturation
author_rank: Super Contributor
timestamp: June 18, 2010, 05:40:44 pm
content: Atten in a peculiar company, they do design their gear rather than rebadge; but they have been linked to making copied designs, one infamous one is the Rigol 1000s series which led to litigation in China. Some posts suggested they are an ODM for low end scopes by LeCroy. Their brand build quality tends to be less refined [compared to when they ODM], and choice of specs often leads to user disappointment compared to other brands.http://www.electronicskb.com/Uwe/ForumPost.aspx?article=au-electronics:5911:13a6720e-08ce-4ef5-8780-39843642e877%40b9g2000yqm.googlegroups.comhttps://www.eevblog.com/forum/index.php?topic=40.msg231#msg231But a power supply is such a low tech device, it would be easy to repair or enhance what they did wrong, so long as those added cost don't equal your savings by buying another brand. If you can see the device, try it, and potential return it, I'd look at it.Otherwise, IMHO, Mastech has a better reputation.Quote from: Hypernova on June 18, 2010, 01:53:14 am

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 19, 2010, 05:35:57 pm
content: As promised, I took the cover off the GW Instek GPS-4303. All in all, impressed, but there are a few strange aspects.http://www.flickr.com/photos/cybergibbons/sets/72157624310102322/detail/The performance so far has been pretty good. It can deliver the full rated power for a good length of time, and can also drive a fairly powerful audio amp.Comparing it to the Caltek onhttp://www.rcgroups.com/forums/showthread.php?t=1030827there are a number of similarities and differences:* Physical construction including heatsink, case, and front panel are very very similar.* Board layout is approximately the same, though noticeably different.* Soldering quality appears to be better on the Instek.* More fuses on the Instek* Extra output transistors on the Instek (I presume for the extra channels)Hard to tell if the Caltek is a clone of the Instek, or if they are made by the same factory, and if so, if they are made to different quality standards.I'm fairly happy anyway.

author: saturation
author_rank: Super Contributor
timestamp: June 19, 2010, 07:21:41 pm
content: Does the Caltek also use a toroidal transformer? These are much better to use for cleaner power, but they cost more than laminated core, so just seeing that in the Instek is a good sign of things to come. The workmanship is very good, and except for that floating PC board, it does look like a 10/10, as expected from Instek.I recently bought the 3A Maxtech I'll dissect later for comparison. I don't expect it to have a toroidal but we shall see.Soldered fuses is something I increasingly see in Chinese designs. It isn't bad these days, as in decades of use I have rarely seen a fuse blow without an internal fault that will require more than just a replaced fuse to fix. In PSU, the overload protection circuits should kick in to make fuses a last resort for safety.Thanks for the photos, CG. Very well done. You also take very good photos, of all kinds of subjects including your friend ... you may have another professional calling if you choose and so could she, she knows how to and has the lines of a model, compared to so many in Flickr. Now back to electronics !Quote from: cybergibbons on June 19, 2010, 05:35:57 pm

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 20, 2010, 08:58:39 am
content: Thanks for the kind comments!The other power supply, the switchmode PSP-2010, I took apart when I first got it (in the true spirit on EEVblog I guess...).The construction quality of this is fairly good again. They seem to have added a sheet of plastic to duct airflow over the choke and power resistor, but outside of that they seem to have got this right first time.There's a good number of ferrite beads, threadlock on most screws, soldering is neat.In use, I'm more than happy with the power supply. The controls are digital, which means I can dial in x volts with a limit of y amps. It also has limits which you can set, so that if you are testing a circuit that has a max vcc of 12v, you can cap it there, and not worry about spinning the dial too far. The power limit is also an interesting feature, but I have yet to use it.RS232 is a good addition. You can both control and monitor the supply using this - the command set is very simple. I'm contemplating adding a cutout and FTDI board so that I can control it with USB. Currently I'm using USB->Serial adapter from about 10 years ago and it's crap.It's a useful supply for powerful projects - motor controllers, RF amps. Also really useful to use as a charger for different battery types as you can monitor and change the charging profile from a PC - I've not written anything to do this yet as the USB->Serial adapter fails all of the time!

author: saturation
author_rank: Super Contributor
timestamp: June 20, 2010, 12:34:10 pm
content: You're very welcome. Thanks again for the dissection.Lots of ferrite beads ~ lots of EMI, as expected from switching PSU, including much smaller, and cheaper type, laminated core transformers. Construction is as you say, very well done.Have you tried looking at its ripple under load, comparing the switched PSU versus the analog one you bought, also at near maximum load? I'm interested in whether the published performance spec is near its real world measured spec.Quote from: cybergibbons on June 20, 2010, 08:58:39 am

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 20, 2010, 12:44:18 pm
content: I'm going to do some tests and post them - but I do need some consistent loads for both of them - 20V at 10A means I need to find something that will dissipate 200W of heat!

author: saturation
author_rank: Super Contributor
timestamp: June 20, 2010, 01:07:57 pm
content: Yes, only if easy enough for you to do. You mentioned you had an ~ 32V/3A load somewhere, and the 4303 has a load regulation spec at 3A of ~0.01%. The PSP 2010 spec is written independent of load, so you could compare it at open circuit and at 3A too.https://www.eevblog.com/forum/index.php?topic=683.msg8431#msg8431Quote from: cybergibbons on June 20, 2010, 12:44:18 pm

author: Zed
author_rank: Contributor
timestamp: June 23, 2010, 09:43:34 pm
content: When you build your PSU use digital for the voltage display and have an analogue display for the current (Moving coil meter or LED Bargraph). 7 Segment LED/LCD displays for current measurement without a bargraph display are almost totally useless even though you see them often on manufactured PSUs.DO NOT PAY GOOD MONEY FOR A MANUFACTURED PSU! They are easy to build yourself.

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 25, 2010, 12:21:05 pm
content: There is no way I could have matched the value of the 4 channel power supply I got - just a quick calculation would put the case, analogue panel meters, terminals, transformer and fan over cost. I should imagine the design has a few more features than the basic supplies I often build.Does anyone actually really trust panel meters when it counts? I always double check the voltage with a meter, and if the current matters to me, I short it to put it into CC mode and confirm that it is right. I'd rarely use it for monitoring.

author: desolatordan
author_rank: Regular Contributor
timestamp: June 25, 2010, 12:41:50 pm
content: Quote from: Zed on June 23, 2010, 09:43:34 pmPlease extrapolate. Do you prefer an analog display because you don't need the precision in constant current mode? I use the constant current mode for a number of things and require it to be just as precise as in constant voltage mode.

author: Unknown
author_rank: Unknown
timestamp: June 25, 2010, 01:06:26 pm
content: Analog meters have a much higher bandwidth, and will show you fluctuating current draw much better. It's also easy to see a needle go to zero or full-scale from the corner of your eyes.

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 25, 2010, 02:30:14 pm
content: Of course, you also get the tell-tale ticking as the needle slams into the stops!

author: Unknown
author_rank: Unknown
timestamp: June 25, 2010, 04:20:41 pm
content: True. I find relays clicking (when a DMM changes ranges) also quite useful for this purpose.

author: Zed
author_rank: Contributor
timestamp: June 26, 2010, 11:18:00 pm
content: Quote from: desolatordan on June 25, 2010, 12:41:50 pmWhen you are supplying power to something the voltage will remain pretty constant (unless there is a fault) but the current will vary proportional to the load. If the load varies then so will the current. With an analogue current meter you can see instantaneous changes in current but with a digital current meter you will see numbers all over the place if the load is not constant.Digital Voltage Meter. Analogue Current Meter. This is THE LAW!

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 27, 2010, 02:10:03 am
content: QuoteA row of LEDs can react even faster than an analog meter and be cheaper to implement.Or how about have a color LCD for the front panel display and allow the user to select the display format using software? Maybe even have a basic "oscilloscope" that can resolve voltage and current variations up to something like 20kHz or so.

author: Hypernova
author_rank: Unknown
timestamp: June 28, 2010, 12:58:48 pm
content: Quote from: NiHaoMike on June 27, 2010, 02:10:03 amA display like that will add a non insignificant chunk of coin to the price that most ppl aren't will to pay for. You are better off making your own small amp meter and have it sit between the terminal and your load.

author: DaveB
author_rank: Newbie
timestamp: July 23, 2010, 12:20:16 pm
content: Along these lines does someone have a general opinion on the new BK 9110?http://www.bkprecision.com/products/model/9110/100w-multi-range-60v-5a-dc-power-supply.html

author: saturation
author_rank: Super Contributor
timestamp: July 23, 2010, 05:51:51 pm
content: A very interesting unique device, roughly its limited by "constant" power, so it delivers more amps at lower voltage and lower amps at higher voltage to the limits of 5A or 60V, whichever is reached first. Its programmable with memories, so its can memorize for quick recall a list of oft used combinations.The specs are good, and the price range is what can be expected of B&K.The 2 issues are, do you need programmability given its ~ $300 price and what do competitors offer?The 'constant' power approach is unique to this B&K. A traditional power supply state amp and voltage limits, e.g. all linears by Maxtech for example, to 30V is about $80, $50 for 15V both at 3A, with similar specs for power regulation but without the programmable conveniences.http://www.mastechpowersupply.com/dc-power-supply/linear-power-supply/mastech-regulated-variable-dc-power-supply-hy6003d-60v-3a-new-model/prod_119.htmlQuote from: DaveB on July 23, 2010, 12:20:16 pm