Power Supply Recommendations - Page 1
Forum section: electronics / beginners

author: burro
author_rank: Contributor
timestamp: February 15, 2013, 03:13:04 pm
content: Hi, I am a newbie and I am trying to choose a power supply. I have read some of the postings here and on other sites and I can't figure out what to purchase yet...What I want:Cheap (Anywhere from $50 to $150)Output button.Linear power supply.Precise (as much as possible)Small (I do not care about several outputs)What I do no t want:Expensive (I am just starting this a hobby)I do not want to build one myself yet. Maybe in the futureI do not want to buy something used (God knows the mileage that that thing has on)I am down to the following models:korad ka3005p (I know dave reviewd this one and failed, but I think he got a bad unit)The Vantek DPS 3305P (Seems not to have the power overshoot problem that the Quakko has.)Uni PS-1303Any thought or recommendations?

author: burro
author_rank: Contributor
timestamp: February 15, 2013, 08:51:16 pm
content: Can anybody help me? Please??

author: c4757p
author_rank: Super Contributor
timestamp: February 15, 2013, 08:56:47 pm
content: Quote from: burro on February 15, 2013, 03:13:04 pmWhat's wrong with mileage? It's just a power supply. You can get some really nice used ones, and the worst "mileage" I've seen on a used power supply is a dent in the cabinet.

author: codeboy2k
author_rank: Super Contributor
timestamp: February 16, 2013, 01:30:49 am
content: Go for the used one. Really.You will easily find a good linear power supply in your price range that is 10 times better than most Chinese PSU's, it will not have the massive overshoot problems that many cheap units have, it will be more accurate and more stable at all loads, and will be over engineered to last a lifetime, not under-engineered with cheap parts operated at their physical limits.bonus... it will have really cool vintage analog volt and current meters on the front panel.If I am building a circuit on a breadboard and I need about 15V and about 50mA then I set it to "about" those values.If I need any accuracy in the settings, I use a DMM.I have been doing it this way for a long time, it's very usable. However, these days I could use yet another PSU, so I am going to build my next one with a digital panel, and can be set to 1mV and 1mA.

author: burro
author_rank: Contributor
timestamp: February 16, 2013, 05:15:17 am
content: Hi, thanks for your response. The problem with buying a used one for me is that I am an newbie and if it breaks I am afraid I would not know how to fix it. For you guys is easy, but I am learning. Also I would like one that has the "output" button, so that I can have it tuned on without transmitting any voltage untill I set it and press the button.

author: c4757p
author_rank: Super Contributor
timestamp: February 16, 2013, 05:20:17 am
content: A lot of them don't have a load switch and it's silly to spend more just to get a switch. Unplug the cable to "switch it off".

author: krish2487
author_rank: Frequent Contributor
timestamp: February 16, 2013, 06:26:30 am
content: It is actually easier to fix an older well known PSU like a TTi or HP rather than a newer chinese cheapo, because of the documentation available.Besides what is the point of getting into electronics if you are not willing to get your hands dirty??Learning to fix a PSU willl teach you LOADS about troubleshooting, and that in my opinion as much important as designing your own circuits and playing around with them.Most the seasoned engineers here would not bat an eyelid when asked about their choice between a HP E3610 and a Korad 3005.They would say HP before you can finish your question.. and it is for a reason.Try reading the service manual for the E361X power supplies and a Korad PSU(which I have not yet come across so far).HP has perfected the art of documentation much before any of the chinese companies existed.

author: burro
author_rank: Contributor
timestamp: February 17, 2013, 01:47:40 am
content: I though about the HP E3610, however the cheapest you can find a used one on eBay is$160(including shipping) and it only does15V @ 2A or 8V @ 3A, while the KORAD (which has almost5 stars on Amazon) is$95and does30V @ 5Aand on top of all that it is programable.

author: Fsck
author_rank: Super Contributor
timestamp: February 17, 2013, 02:24:50 am
content: The fact that such an old and "low" output unit sells for that much should give you an indication of it's quality.I myself have an E3630A and an E3620A from that family and various other units of other types. These units are proven to be excellent over more than a decade along with excellent background material.

author: c4757p
author_rank: Super Contributor
timestamp: February 17, 2013, 02:39:31 am
content: Do you really need that much current? I do a pretty wide range of stuff and most of the time I use my 500 mA power supply...

author: amspire
author_rank: Super Contributor
timestamp: February 17, 2013, 03:23:23 am
content: Another vote for a quality used power supply. The manuals for the HP supplies are magnificent and they are not hard to fix. As the components tend to be overrated, you are unlikely to get a blown transformer. Basically, the supply will last for decades.CI would be surprised if any of the chinese supplies have any kind of service manual, and with the more complex digital circuitry, they are far more likely to be irrepairable if they fail.It is really extremely rare to need a programmable supply, and many of the old HP supplies have something that may even be more use. On the back, there are terminals with all the supply, sense, voltage and current sense connections. You can set the supply to switch between output voltages and currents with a relay and some resistors.My preference is for conventionally cooled supplies with no fan for my day-to-day work. A switching supply would be a good addition if I need high current.Doesn't have to be as recent as a E3610. The supply I use the most is a HP 6227B dual 25V 2A supply from 1970. Fairly compact with a massive transformer and massive quality Sprague capacitors.

author: krish2487
author_rank: Frequent Contributor
timestamp: February 17, 2013, 04:13:26 am
content: Have a look at the prices for HP E3610 and the agilent U8001 power supply on the agilent site.The U8001 costs about 330$ give or take and the E3610 costs about 470$.That is the pedigree of the E361X series that, Agilent after buying out HP did not discontinue the product.Granted, they are trying to milk out more money for the reputation of the E361X series but such is their reputation.As amspire suggested, go for an older generation HP model within your budget.You said your budget was about $50 - $150. Spend ten bucks more and get "actual" value for your money.It might seem worthwhile to get a $80 chinese power supple now but when the power supply fails, and it will fail soonyou ll be in a tight spot.Even if the power supply does not fail, there is a fairly high chance it will blow out a couple ofcomponents you are testing due to the massive overshoot.Compare the specs for a momentHP E3610 -15V @ 2A=30 WattsKorad -30V @ 5A=150 WattsRest assured that the Korads rating is absolutely rubbish, while the HPwilldeliver the rated 30 watts continuously.I concede that Dave might have gotten a bad unit, whats to say you wont?Are you really willing to gamble $95 on a PSU?Where is it assembled, who assembled it, whats the companys track record?As C4757p said, for any started bench experiments,500mA - 1A is the limit.Most of the split supply semiconductors(not bipolar semiconductors) max out at+/- 15Vand about10-25 mA MAXEven if you were to run about 10s or even 100s of such semiconductors and associated circuitry on your bench (highly unlikely and not practical, but just for arguments sake) you ll still be drawing about3~5 wattsmax.No one here is trying to ostracize you or criticize your choice, the final call is still yours to make - we are just trying to help you make an informed decision since you asked for help.

author: BravoV
author_rank: Super Contributor
timestamp: February 17, 2013, 04:25:39 am
content: Quote from: krish2487 on February 17, 2013, 04:13:26 amTo be honest, I think I roamed & lurked enough at too many electronic forums, imo, currently here in this very forum probably is the best place at internet to ask for an advice for a bench top PSU either used,new,pro-grade or even hobbyist grade.

author: c4757p
author_rank: Super Contributor
timestamp: February 17, 2013, 04:26:56 am
content: Quote from: krish2487 on February 17, 2013, 04:13:26 amI'd add that while my 500mA supply (a really nice Power Designs precision model, voltage resolution to 100uV with an ovenized reference) is more than enough formostthings, there have been times I'd have been up the proverbial creek without a paddle if I didn't have a higher current supply. I would not recommend one that weak as someone'sonlysupply. However, I can't think of too many uses for a 5A supply. The only thing I've ever used my 5A supply's upper limit for is testing an electronic load, and I'm sure I could have found something else to source that current for such a temporary purpose.

author: rsjsouza
author_rank: Super Contributor
timestamp: February 17, 2013, 04:40:07 am
content: The point that everybody is trying to make is: don't let features alone lure your decision - especially in instrumentation, where a robust technical design is far more important. Given that power supplies are absolutely critical for any electronic circuit, its quality is crucial to remove any guessing that you may have when designing your electronic circuit.

author: krish2487
author_rank: Frequent Contributor
timestamp: February 17, 2013, 04:43:26 am
content: @BravoVI ll admit I have refrained from asking questions in many a forum due to fear of getting criticized or browbeaten.I also admit my post above might have been misconstrued as harsh and blunt.I just wanted to make sure that the OP does not feel the same.The fact that the discussion is being held on a online forum does not mean we do not bring courtesy to the table.I only look at it as an opportunity to draw from the infinitely more experienced folk around here and learn or understand.Yes, EEVBlog is my number one go-to forum for posting any sort of question, suggestion, achievement(which are non-existent, i admit)Primarily due to fact that people here are benign and helpful most of the time.

author: ChrisW
author_rank: Contributor
timestamp: February 17, 2013, 08:01:40 am
content: I am going to ask a silly question here but can 230VAC devices be plugged into 240VAC without causing any problems? I am in the market for for a E310 but can't find any 240VAC models.

author: SeanB
author_rank: Super Contributor
timestamp: February 17, 2013, 08:42:17 am
content: In most cases yes, as they are essentially the same voltage when you look at the voltage tolerances. The only issue is if you have marginal heatsinking, where the extra heat will cause long term issues. As an aside most single phase motors are wound for 200-220v input voltage, they do have a short life on 230/240V mains areas which spend most of the time on the high side of the tolerance range.

author: burro
author_rank: Contributor
timestamp: February 17, 2013, 03:44:56 pm
content: Ok I tried to follow everyone's advise to buy the HP power supply but I was outbid at the last second on eBay. So I am going to go with the Korad (God help me). I'll test it with my brand newRigol ds1052e ociloscope, which I bought for just$314including shiping (and, no, I did not buy it on eBay or china, so it has full warranty). If anybody wants the tip on how to get it let me know.

author: burro
author_rank: Contributor
timestamp: February 17, 2013, 11:56:03 pm
content: After purchasing the Korad, I saw this video by Dave, now I feel much better about my purchasehttp://youtu.be/_HrvuHSywms

author: codeboy2k
author_rank: Super Contributor
timestamp: February 18, 2013, 10:08:20 am
content: Quote from: burro on February 17, 2013, 11:56:03 pmCan you post your turn-on waveform (i.e. no load startup rise time and any overshoot).Plus test a few voltages, like 1V, 3.3V, 5V, 12V, 25V see how it overshoots or not.Test with no load first, and then with a 5-10mA load at each voltage point, with the load connected before you turn the output on.This will give you a feel for the quality of the supply.Thanks if you can do this and post your DSO screen shots.cheers!

author: burro
author_rank: Contributor
timestamp: February 19, 2013, 02:30:45 am
content: I sure will now that I see somebody is interested, I might even post a video, but please don't laugh... I am am a newbie who abandoned Electrical Engineering (for industrial engineering) because I thought electrical was beyond my brain's capabilities.

author: Telstar
author_rank: Contributor
timestamp: February 22, 2013, 07:45:03 pm
content: curious to see the waveforms

author: Analogtech
author_rank: Contributor
timestamp: February 23, 2013, 08:31:19 pm
content: Why not modify a PC powersupply and program an arduino or something to give you a readout? they serve pretty well and you can always (well most of the time) fix them easily and they cost tuppence compared to an actual bench supply

author: Paul Moir
author_rank: Frequent Contributor
timestamp: February 23, 2013, 09:11:01 pm
content: Generally because they're lacking a few features. They are not variable voltage (and it is very difficult to make them reliably adjustable even over a small range, never mind a wide range). They have no adjustable current limiting. Getting more than 12v out of them is a lot of trouble usually solved by using two. Also the poster is looking for a linear power supply. Linear supplies are less noisy than cheap computer supplies, and typically will handle odd loads more gracefully than a switching supply. Note that a really nice switching supply doesn't really suffer all these faults, but are more expensive than a cheap linear.

author: FenderBender
author_rank: Super Contributor
timestamp: February 23, 2013, 11:17:10 pm
content: As many others have said, a low power <1A (hell <500mA) is usually enough for most circuits you will work on. It's better to have a solid low power supply than a super-high power 30A supply that is marginally stable.Computer power supplies are good at what they do, but for electronics design, not so much.

author: george graves
author_rank: Super Contributor
timestamp: February 24, 2013, 01:48:04 am
content: Quote from: krish2487 on February 16, 2013, 06:26:30 amOr you'll get so frustrated trying to fix the thing you'll give up the hobby altogether. I don't recommend newbies building their own test equipment - it's a recipe for disaster. Not when there are plenty of "decent" Chinese stuff out there. Sure - you might out grow that korad - but it's a good deal for the money. Personally, I would splurge for an older HP unit - but if you're strapped for cash, go for the korad.

author: krish2487
author_rank: Frequent Contributor
timestamp: February 24, 2013, 03:30:26 am
content: I did mentionfix.I did not hint about a newbie making their own offline power supplies. Thats just a death-wish.Given a properly detailed service manual, a newbie can fix a bench power supply from a pedigree company relatively easily.

author: george graves
author_rank: Super Contributor
timestamp: February 24, 2013, 04:24:57 am
content: yea, but still....

author: burro
author_rank: Contributor
timestamp: February 24, 2013, 04:38:58 am
content: Guys I just received the KORAD and it looks pretty good, I have not tested it yet because I think my ociloscope came broken and I am going to have to return it(I will be posting a video so you guys can see what the ociloscope is doing), but I did open up the KORAD I bought from Amazon and it is the new redesigned model. It looks pretty sturdy, it certainly does not look or feel cheap at all, it even has some Nippon capacitors inside.

author: burro
author_rank: Contributor
timestamp: February 24, 2013, 06:35:30 am
content: Here are the Korad pics... It looks pretty nice inside overall, except for some big grey resistors on the power supply that look as if they got melted and then painted by hand (i'm posting pictures of those too) I will test it when I get another oscilloscope in the mail since the Rigol ds1052e I bought came broken from factory.