Purchasing a lab power supply - Page 1
Forum section: electronics / testgear

author: aruna1
author_rank: Regular Contributor
timestamp: March 03, 2013, 11:33:29 am
content: hi guyscollected some money and trying to purchase my FIRST benchtop power supply.I looked in aliexpress for a supply that fits to my budget and I have four optionsAtten APS-3003http://www.aliexpress.com/item/DHL-EMS-Free-shipping-ATTEN-APS3003Si-mA-Class-Adjustable-Linear-Regulated-0-30V-3A-DC-Power/574726749.htmlArts APS-3005 (same as atten i guess but with 5A)http://www.aliexpress.com/item/DHL-EMS-Free-shipping-ATTEN-APS3005SI-DC-Power-Supply-single-channel-low-ripple-and-noise-high/577694277.htmlRXN-303http://www.aliexpress.com/item/Free-shipping-RXN-303D-LINEAR-DC-ADJUSTABLE-POWER-SUPPLY/693660747.htmlDPS-305CFhttp://www.aliexpress.com/item/5Ps-220Vof10V-Adjustable-dc-Digital-Control-30V-5A-Voltage-Power-Supply-DPS-305CF-storage-lock-for/729353120.htmlI'm little biased to DPS-305CF as it has output on-off button and program memory.but it is missing ability to adjust the voltage real time. (for example to check voltage cut-off circuit we can turn the voltage adjust knob of other power supplies. but since this has keypad i cannot do it)so what do you guys think? which one should I go for?thanks

author: Bored@Work
author_rank: Super Contributor
timestamp: March 03, 2013, 01:13:02 pm
content: In the end it is your choice. Such is life. Your risk, your money.What you have there is a roundup of very typical low-end Chinese power supplies. There are hundreds of them out there, some are build OK, others are pure crap. You can't judge them from the outside, since manufacturers copy from each other or use the same enclosure suppliers. You can't even trust the same "brand" and type, because building quality varies, manufacturers change the inside without any indication, and some "brands" get faked.In general, the ones you have picked there form Ali all seem to be a bit expensive for the typical Chinese supply. I have seen cheaper ones new on ebay.For general bench usage I would go for one with a real knob, not a keyboard.

author: jpb
author_rank: Super Contributor
timestamp: March 03, 2013, 02:09:29 pm
content: I guess that you're not located in the UK and power supplies are heavy and expensive to ship. But just in case, I've been very happy with my TTi PL320QMD which I got fromhttp://www.test-measure.co.uk/The supply is an old model TTi, hence sold cheap but it was brand new and shipped directly from TTi.

author: aruna1
author_rank: Regular Contributor
timestamp: March 03, 2013, 02:57:02 pm
content: Quote from: Bored@Work on March 03, 2013, 01:13:02 pmHi price on ali express is cheaper than ebay. at least when considering shipping to Sri Lanka. Atten seems good brand among chinese items like Rigol, dont you think? There are cheaper once at ebay with analog volt/current meters but I'm looking for supply that has digital displayQuote from: jpb on March 03, 2013, 02:09:29 pmHiI'm from Sri Lanka.

author: krish2487
author_rank: Frequent Contributor
timestamp: March 03, 2013, 06:33:04 pm
content: We have been through the same over and over again...Any older HP/Agilent/TTi/Tek power supplies anyday over ny of the newer chinese crap.Just search around patiently on ebay for a used pedigree power supply.At the most you ll have to replace the electrolytics and maybe the power transistors..The newer chinese power supplies are a disaster waiting to happen.Ebay is your best friend in this case.. You ll get a good deal including shipping to Sri Lanka if you are patient..

author: KJDS
author_rank: Super Contributor
timestamp: March 03, 2013, 09:08:19 pm
content: I just checked to see how much shipping would be from the UK to Sri Lanka for one of my TS3022S that I'm currently selling a lot of.Shipping came out to £118 which probably rules out buying one from the UK.

author: gearhead
author_rank: Contributor
timestamp: March 05, 2013, 12:58:21 am
content: I agree that the Chinese PS are waiting to go out on you. I have several units, three HP's, one Electronic Research Associates, and a Lambda that I use every day. The Lambda is a VERY well made unit. It and the HP's can be repaired pretty easily if something happens to them. But it's all about what you can afford! GOOD LUCK!

author: nctnico
author_rank: Super Contributor
timestamp: March 05, 2013, 01:11:14 am
content: I have been eyeballing this PSU for a while:http://www.ebay.com/itm/261050328132I like the fact the maximum current depends on the voltage. A PSU is most universal that way.

author: icpart
author_rank: Regular Contributor
timestamp: March 05, 2013, 06:54:05 am
content: Hi aruna1.If you can build itself benchtop power supply like these which I found some times ago with these great project from Felixls here:http://sergiols.blogspot.com/search/label/Digital-Power-Supply-2.0I also like to modernize my old homemade linear power supply made around LM317 with current expansion with 2N3055 and some modification from me for overcurrent protection but without current limiting with these digital power supply.

author: EEVblog
author_rank: Unknown
timestamp: March 05, 2013, 11:18:01 am
content: Quote from: aruna1 on March 03, 2013, 11:33:29 am0.1mA current display resolution? that's impressive (if it's accurate). Must be using a 16 bit ADC for that.Dave.

author: mzzj
author_rank: Super Contributor
timestamp: March 05, 2013, 12:24:13 pm
content: Quote from: gearhead on March 05, 2013, 12:58:21 amI would say that many(most?) of the Chinese power supplies are mechanically more robust than HP/Agilent 6632B for example.6632B front panel and display are the weakest link, way too easy to break. Not so much problem if You have proper equipment rack or even keep your power supply at the table. Not so nice if you have to transport or move it around or ship the power supply to another side of the earth.Accuracy and feature-wise secondhand 6632B is unbeatable. Especially current measurement, You need pretty good DVM to do better than 6632B can do.

author: gearhead
author_rank: Contributor
timestamp: March 05, 2013, 09:29:26 pm
content: That could be right on the HP supply you mentioned. Mine are older, I have a 6202B, 6205B, and a 6215A. They ALL seem cheaper made than my Lambda. But the 6215A is a pretty solid LITTLE unit! And has a very good fine voltage adjustment on it. But none of these are digital anything. I've been a fan of Lambda supplies for a long time. The US Military used them for a good reason, they're tough and dependable! Mine is an LH125FM that I gave $20 for. Works GREAT! If I need another PS, I'll try to get another Lambda.

author: krish2487
author_rank: Frequent Contributor
timestamp: March 05, 2013, 10:18:54 pm
content: QuoteExactly!!A little patience goes a long way.Why spend a lot more on a questionable source rather than spend relatively little on a more pedigree maker??I myself have bought a HP6206 recently for $20 and it is still spot on.The build quality is worth talking about though..All I am saying is any used known PSU is always better than a new chinese one.Especially what you can find on aliexpress and dealextreme!!.

author: dimlow
author_rank: Frequent Contributor
timestamp: March 06, 2013, 01:24:32 am
content: Quote from: EEVblog on March 05, 2013, 11:18:01 amSpecs for that unit are +/-1mA on the display. My guess is its a 12 bit ADC. For 5A that would give 1.2mA resolution.I have been looking at these cheap power supplies for a while now. Today i came to the conclusion that I'm better off getting a used quality unit. Will be getting a used Thurlby Thandar dual channel, big and bulky and already 10+ years old. But the specs and usability/ reliability are quoted as being far better than any of the cheap Chinese crap.

author: reagle
author_rank: Unknown
timestamp: March 06, 2013, 02:04:14 am
content: Another vote here for a used brand name one. With enough patience HP E361x can be had for $60-$70. Sure it'll probably be 15 years old, but will last at least as much after it. And you can fix it if it breaks.

author: dimlow
author_rank: Frequent Contributor
timestamp: March 06, 2013, 03:48:34 am
content: Just got ordered one ofKJDS's suppliesneeded the extra one for teaching my kids as they are now getting into electronics. Next order a is another pickit as my oldest has"borrowed my other two pic programmers" for a project.

author: metalphreak
author_rank: Frequent Contributor
timestamp: March 06, 2013, 08:45:22 am
content: I have a massive Zhaoxin Dual 30V/10A supply that's been working well for >2yrs now. They seem to be a better brand of chinese supplies (and you'll never find them as the cheapest ones possible to buy). They also do a lot of high current/rack mount supplies, so they're not solely a low end manufacturer. The adjustable Vantec branded PSU I have works great as well. However, some variations (under other brand names) have issues with turn on voltage spikes due to rubbish firmware on them.Everyone goes on about buying a second hand top tier supply like a HP or Agilent etc. Getting one of these for ~$100 is like winning the lottery. Especially in countries where they aren't sold often 2nd hand. Big heavy supplies usually have $70+ for shipping alone from overseas. Even within Australia, getting one from the eastern states to WA costs $30-40.Have a look around for a good second hand one. If nothing is available - in good working condition no less - then go for one of the chinese supplies. Just make sure its not a rock bottom built down to the last cent piece of crap. There's no point buying a dodgy second hand 20yro HP if its likely to fail. It'll just cost even more to fix then.gearhead / krish2487: I notice both of you are from the USA. Used test equipment is *much* easier to get in the USA. It's also 110V only in many cases. No good for anyone on 240V. Have you seen how much it costs to send items out of the USA? I had a car amplifier shipped to Australia from the USA. It was $110 shipping! (it was fairly large though). However still worth it because the price was so good

author: nctnico
author_rank: Super Contributor
timestamp: March 06, 2013, 04:43:30 pm
content: I agree. Many years ago I bought an HP6002A PSU with some problems due to charging a battery which caused the overvoltage protection to trip when it overheated... Besides some burned traces I also noticed the wires which where soldering directly into holes of the PCB got loose. I had to redo them all.Shipping can be expensive but if the item is worth it... I once bought a huge logic analyzer complete with accessories for US $66. Shipping cost me another US $350.

author: KJDS
author_rank: Super Contributor
timestamp: March 06, 2013, 09:15:25 pm
content: Quote from: dimlow on March 06, 2013, 03:48:34 amThanks for the order, I've just finished packing it, should be with you on Friday.

author: dimlow
author_rank: Frequent Contributor
timestamp: March 07, 2013, 12:31:15 am
content: Thanks for that, hopefully we can have a play here over the weekend.