Power Supply - Page 1
Forum section: electronics / general

author: coreybus
author_rank: Newbie
timestamp: October 06, 2013, 11:52:58 pm
content: Looking for a reasonably cheap, yet trustworthy variable power supply that i can power some engineering projects with in Melbourne Australia

author: Stephen1424
author_rank: Newbie
timestamp: October 07, 2013, 06:22:04 pm
content: What ranges are you looking for ?

author: elektronchika
author_rank: Contributor
timestamp: October 07, 2013, 07:15:24 pm
content: I can recommend you TENMA (KORAD) 3003 or 3005. Very for for the price, digitaly controlled power supply. Very good option is the output on/off, without the need to turn on/off the whole power supply.

author: Ricardodavinci
author_rank: Contributor
timestamp: October 09, 2013, 11:32:05 pm
content: Rigol DP832, not so expensive, high quality bech psu! Dave made a nice review on youtube. I'm about to buy one of them for myself. We also use them at the university.

author: walshms
author_rank: Regular Contributor
timestamp: October 09, 2013, 11:38:53 pm
content: If I recall, Dave's review found these could overshoot a bit to a noticable amount when the load is switched on. Test thoroughly before depending on that, but a Korad might work well for you as an inexpensive supply.A Rigol won't overshoot, but it's a lot more expensive.

author: Ricardodavinci
author_rank: Contributor
timestamp: October 09, 2013, 11:41:34 pm
content: I'm pretty sure that Rigol has solved the design problem for now!

author: Unknown
author_rank: Unknown
timestamp: October 10, 2013, 03:16:23 am
content: The overheating issue has been solved, but I'm not sure if fixed boards have made it to all distributors yet. Be sure to inquire. The overshoot issue was also reportedly solved, but I haven't seen any confirmation of this. No word yet on the sense connection for channel 2/3 as far as I know.

author: jmcdonald
author_rank: Contributor
timestamp: October 11, 2013, 12:19:31 pm
content: Quote from: Ricardodavinci on October 09, 2013, 11:32:05 pmI am all so looking at buying one of these units at the end of the year. Has any one hacked this unit yet maby upgraded to a DP832A is the hardware the same?

author: andtfoot
author_rank: Unknown
timestamp: October 12, 2013, 08:03:13 am
content: Quote from: gazelle on October 12, 2013, 07:19:17 amFrom what I can see, the Korad unit has its known issues fixed as per the later videos from EEVblog and TrioSmartCal:The Rigol DP832 has its own share of issues which I believe are just about fixed up now. Rigol is currently distributing a new hardware revision but I haven't seen any follow up tests yet.

author: Wytnucls
author_rank: Super Contributor
timestamp: October 12, 2013, 08:14:53 am
content: If you want something cheap, a Chinese power supply like this one should be sufficient to power your projects you for a while:http://www.ebay.com.au/itm/DAZHENG-30V-5A-VARIABLE-DC-POWER-SUPPLY-DIGITAL-DISPLAY-LAB-GRADE-PS-305D-/271288677536?pt=AU_B_I_Electrical_Test_Equipment&hash=item3f2a10b4a0

author: TheInternetAddicted
author_rank: Newbie
timestamp: October 15, 2013, 03:10:28 am
content: I always just use an old PC power supply. not very precise, but good enough for most simple projects

author: jmcdonald
author_rank: Contributor
timestamp: October 15, 2013, 10:49:35 am
content: Quote from: TheInternetAddicted on October 15, 2013, 03:10:28 amRemember to put a small load on the 5v rail I've always used a 4.7? 10W resistor

author: dr.diesel
author_rank: Super Contributor
timestamp: October 15, 2013, 10:59:00 am
content: Quote from: Ricardodavinci on October 09, 2013, 11:32:05 pmAs nobody has a rev 3 unit, currently the DP832 is a poorly designed utter piece of garbage. There is no way Rigol let it out without knowing how serious this was, and if they did they should fire the design/review board and QC teams.Plain and simple, Dave's teardown/review forced their hand.

author: Ricardodavinci
author_rank: Contributor
timestamp: October 19, 2013, 06:42:20 pm
content: I'm about to build one myself. I've come over some switching IC (oldschool multiwatt 15-pin) but capable of switching up to 40V of input and constant give about 10 amps of output. I have a nice couple of transformers (28VAC 10amp) in my bin, and just need to design a board and build it! Total cost? About 50 bugs! The chip I'll use is called L4970A.

author: echen1024
author_rank: Super Contributor
timestamp: October 20, 2013, 04:37:24 am
content: A used Agilent E3610 maybe? That's what I use now, and I am very satisfied with it.

author: jmcdonald
author_rank: Contributor
timestamp: October 23, 2013, 04:30:55 pm
content: I would incorrige any one to build there own power supply I built a little 5 amp 30v power supply in my first year studying electronics, 4 years ago then strait away started building a isolated dual output 20amp 30v and 10amp 30v cc cv power supply all the pcbs are made holes are drilled in the face plate transformers mounted heat sinks mounted just needed to make the wiring harnesses and finish assembly. That was 3 years ago I guess I will finish it one day.

author: staxquad
author_rank: Frequent Contributor
timestamp: October 24, 2013, 02:46:48 am
content: Quote from: Wytnucls on October 12, 2013, 08:14:53 amthey claim it's "Australian Proof"is that something like Idiot Proof, or are they hinting at something altogether different?

author: Bored@Work
author_rank: Super Contributor
timestamp: October 24, 2013, 05:18:00 am
content: Quote from: staxquad on October 24, 2013, 02:46:48 amThey probably mean they have some australian safety certificate. I.e. someone sold them a bunch of certification stickers and they managed to stick them on the case before shipping.

author: bench_knob
author_rank: Regular Contributor
timestamp: November 04, 2013, 12:46:53 pm
content: Quote from: staxquad on October 24, 2013, 02:46:48 amHi All,I bought one of these recently on eBay, only the label is marked "Arkensen 305D". When I got it, I noticed that the top of it was spattered with something was a bit like jelly, only it was oil based and required a bit of rubbing with soap to eventually remove it. And then, the display lens had greasy finger finger-prints on it.I got out my 250Watt 6 Ohm resistor and cranked up the supply to 30V @ 5Amps, well, it coughs up 5Amps (according to the display) at 32Vdc, and it did so for several hours, but the supply became fairly warm. Then I pulled out a 1 Ohm 250 Watt resistor for the 5Volt test, it doesn't meet specs.I noticed that there was finger-prints on the inside of the lens, so I removed the case to clean off the lens, and lo and behold, I noticed that the power-supply is missing a power-mains fuse??! So I started poking around and another surprise, the main board (there are several boards) is marked "Long WEI PS-303D-M". In fact the display board, (two single-chip A/D chips for Volts & Current display) is also marked, "Long WEI PS-303D). So, without having a PS-303DM power-supply to compare my new PS-305DM, I have to presume that the two power-supply models are very likely the same, at least by this vendor, and that they just stick on different labels. The coding for the power-supplies, according to the Long WEI factory website in China, the "30x" is the voltage, while last digit is the current, and yes, they do manufacture a 3Amp power-supply. The "D" represents digital, as they previously manufactured dial-meter readouts, and the -'M' means that the power-supply can be switched between for Ampere and miliAmpere ranges. The front panel sports a push-button switch marked Hi/Lo for that function, apparently.I asked the factory for a schematic and they essentially told me to go fong-myself. So, I'm tearing it down, taking a photos of everything and later, after I return from giving my "ET instrumentation" lecture at a large San Jose, California UFO convention next week, I'll finish it up and post what ever, if anyone is interested?Oh, and it says that its ROHS and CES certified, but its all lead-based solder and how could it be CES with no fuse? It was only $69 + free shipping (24 Lbs), else I'd ship it back, its not hardly worth it and since its not broken, they'll argue and wanna stick me restocking fee too probably. I'd have to tell them that I opened inside of warranty. So screw it. So I'm the proud owner of a non-ROHS, non-UL, non-CES, 5A labeled 3A power-supply, that's obviously been repaired. But in my defense, it was those digital displays that hooked me. I got a thing re; LED displays.After buying that junk, I broke down and bought a nice old HP6632A, 20V @ 5A, programmable, constant current, constant voltage, GPIB controllable power-supply. I used one in the lab at ITT AeroSpace Comm Div for powering up our L2C GPS control-segment prototype digital-signal-processor/receiver we were developing for the upcoming L2C Civil Tracker GPS System (NGA). (We also built the SVs.) The HP, well, its a great power-supply. It is so slick power-supply and it was only $150, but its a veritible boat-anchor. But I wanted a 24V @ 5A supply for some steppers I got laying around. Hah!Enough yakkin.bench_knob

author: Wytnucls
author_rank: Super Contributor
timestamp: November 04, 2013, 02:01:02 pm
content: Are you sure the mains fuse is not incorporated in the plug, like on this one?:Here is a pic of the mains plug at the back of the unit:

author: Wytnucls
author_rank: Super Contributor
timestamp: November 04, 2013, 02:09:26 pm
content: In fact, the plug has a fuse (on the advertised display unit at least). After some enhancement, the picture shows the recess for the fuse. Perhaps the unit they shipped to you is different though.

author: madires
author_rank: Super Contributor
timestamp: November 04, 2013, 02:29:29 pm
content: What would you expect from an US$69 incl. free shipping PSU? Actually it's quite amazing how much you get for that price! Much better than a DIY LM317 PSU ;-) Regarding the circuit I'd expect 3 2N3055, some OPamps and 2 or 3 relays for switching taps.

author: Wytnucls
author_rank: Super Contributor
timestamp: November 04, 2013, 02:37:08 pm
content: You said:'Then I pulled out a 1 Ohm 250 Watt resistor for the 5Volt test, it doesn't meet specs.'I'm curious, can you elaborate on your test and tell us why it didn't meet its specs?

author: grndkntrl
author_rank: Newbie
timestamp: November 04, 2013, 05:19:45 pm
content: Quote from: Wytnucls on November 04, 2013, 02:37:08 pm

author: Phaedrus
author_rank: Frequent Contributor
timestamp: November 04, 2013, 06:15:58 pm
content: Quote from: jmcdonald on October 15, 2013, 10:49:35 amThe need for this can be avoided by buying a PSU with a "DC-DC" topology. They're basically just a +12V power supply with a pair of buck regulators for the +5V and +3.3V. PSUs with that design also typically have lower ripple and better regulation than those using multi-tap transformers.

author: bench_knob
author_rank: Regular Contributor
timestamp: November 05, 2013, 03:18:57 am
content: Quote from: Wytnucls on November 04, 2013, 02:01:02 pmHi Wytnucls,Hmph...yep there is a fuse in the AC mains socket. :-oRe; the tests...Basic configuration, resistor connected to power-supply with an external current meter in wired in series and an external voltmeter wired across the power-supply output posts.I used two DVMs, a Fluke 77 DVM configured for 10Ampere range and a Kelvin 400LE DVM configured for volts 20Vdc range.I set the PS305DM power-supply voltage to 30 Vdc, (high ampere mode), connected in series with 2x 3? (Ohm) 250 Watt resistors. I setup a 12Vdc fan to cool the resistors.The power-supply's internal voltage & current LED readouts displayed 32V at 5.1 Amps, while the Fluke 77, (10Amp configuration), showed 4.99 Amperes, and the other DVM (Kelvin 400LE - Volts configuration), displayed 32 Volts. I was only able to attain a reading of 5Amps, by pushing the power-supply current control up to 5.0Amps, which pushed the Voltage up to 32Vdc.At test start, I measured the ambient temperature (ExeTech 42529) around the pwr-sup case with an IR pyrometer, 23ºC (73.4ºF), after 1hr of operation under load, the temp had risen to 35.4ºC (95.72ºF), and two hours later (three hours total) ?41.2ºC (106.16ºF). It didn't meet specs, it barely produced 4.85 Amperes. I also verified the resistor before and after readings. It was spot on.For the 1? (Ohm) 250 Watt resistor test, I set the power-supply for 5 Volts at 5Amps, it didn't meet those specs either. In fact the readings were 4.99Vdc at 3.87 Amps and no amount of fiddling with the controls would enable it to be 5Volts at 5 Amps.Just some thoughts...There are two power transistors, (TO3) 2N3055 (isolated) mounted on a large flat 10ga aluminum plate. The output posts have two 100 uF 50Vdc electrolytics, .1 uF and has a 1N4008 power diode (K to out+) (A to out-) across the output. The display board, is connected using #28 ga stranded, wires. I think its power for the display board. When I get back, I'll finish the schematic then no more guessing.I did find on some website somewhere (I forgot), someone posted a Protel PS305D schematic, and while it (slightly) follows the board I have, the part nomenclatures are completely different R1As are R101s, etc. Some of the parts are the same, whle the opamps are different. There is only one power pass transistor, the schematic is very poorly drawn. So far I have counted around 12 different manufacturers/labelers who offer what apparently are clones of one and another's products, while enclosures (sans the label) are apparenty identical.bench knobwhats wrong these boards today? This is the third bbs that doesn't support unicode characters. Here, I insert them in edit mode and they preview ok, but when I post, the characters are replaced with a '?' mark.

author: Wytnucls
author_rank: Super Contributor
timestamp: November 05, 2013, 08:02:14 am
content: You need to measure the actual resistance of your rig, i.e. resistor, 3 cables and DMM shunt resistance. Since the total resistance will be higher than 1 Ohm and 6 Ohms, by Ohm's law, you will always be short of 5A at 5V and 30V.The LED displays on these cheap power supplies are never very accurate. It is usually possible to tweak the displays internally for better accuracy, if required.Even if the power supply struggles at 5A, at that price, most hobbyists will be satisfied with its capability in the lower range.

author: bench_knob
author_rank: Regular Contributor
timestamp: November 21, 2013, 04:02:24 pm
content: Quote from: Wytnucls on November 05, 2013, 08:02:14 amHi There WytNucls,QuoteYep, and there's no harm to reiterate even so. Thanks.QuoteActually this one is not too bad, it uses a GC7137AD single-chip voltmeter. I am currently doing a tear down of the unit and I have sourced everything except the voltmeter chip. I have not been able to track down the manufacturer or a spec sheet for 24 pin DIP part. However there are numerous Alibaba/AliExpress agents selling the part for around $0.50 ~ $1.00 each. I don't suppose you might know who the manufacturer is? I've hit all of the datasheet servers that I use regularly in my work. Its frustrating. I just don't speak enough Mandarin!!QuoteI completely agree, for $69 (+free shipping), its a great little power-supply!! And there is always a car battery charger!! I mean who really uses 5A today for anything? Electronics today is mostly below 5Volts, the power-supply (so far) is reasonably stable in the 1.5Vdc to 5Vdc range, with my primary focus being at 3.3Vdc for MCUs and other little toys.For my important projects, have HP6291A (40V @ 5A w/current limiting) HP6632A 20 Vdc CV/CC @5 Amperes (HPIB programmable CV/CC current limiting, + remote sense, etc), for doing analog work.I bought the PS305 power-supply because it is physically small, and 'cause I wanted to try these little units out.As you said...its $69!! In retrospect, what's there to be disappointed about?Cheers,bench knob

author: Wytnucls
author_rank: Super Contributor
timestamp: November 22, 2013, 06:56:39 am
content: The datasheet is difficult to obtain, even for people in Hong Kong:This is Sherry from customer service department. It’s my pleasure to help you.I’m sorry we didn’t find the datasheet you want. I suggest you get it to suppliers directly or through other ways. Or, please click our webwww.hkinventory.comto search your part no, there will be some suppliers for your choosing, then you can ask them for the datasheet.Please feel free to contact us if you have any question, thanks!RegardsSherry PengCustomer Service OfficerHong Kong Inventory LimitedTel: +755 8364 7407Fax: +755 8364 0218Email: sherrypeng@hkinventory.comSkype: HKI-SherryPengWebsite:www.hkinventory.com

author: GreyWoolfe
author_rank: Unknown
timestamp: November 24, 2013, 03:41:40 pm
content: I agree with etchen1024, I have an E3610A that I picked up off eBay for less than $150 USD shipped. I also built and modded an Elenco XP720K kit. The kit cost me $53 shipped and I added roughly another $35 in parts (I don't want to dig up all the receipts). I put all better quality caps, added reverse voltage and bias diodes, discharge resistors, a digital panel meter and will be adding an output on/off switch. Supply is quite accurate measuring the output on my fluke 8840A.Tom NW0LF

author: TheRuler8510
author_rank: Regular Contributor
timestamp: April 08, 2015, 04:39:12 pm
content: Quote from: bench_knob on November 04, 2013, 12:46:53 pmBench_Knob--did you ever post photos of this unit anywhere?I recently got a dead one for next to nothing and I need to replace a resistor on the main board but it is burnt to a crisp and can't tell what the value is. If you had a pic, of the main board, I could tell the value.Any help appreciated.Thanks,

author: Zucca
author_rank: Unknown
timestamp: April 08, 2015, 04:46:25 pm
content: https://www.eevblog.com/forum/testgear/mastech-dc-power-supply-hy3005dx-cheap-and-very-impressing!/msg493821/#msg493821

author: TheRuler8510
author_rank: Regular Contributor
timestamp: April 08, 2015, 11:12:06 pm
content: Quote from: zucca on April 08, 2015, 04:46:25 pmNice--thanks for the pics. Any idea what is the value of the resistor that the red arrow is pointing to? It is also known as R144.Thanks

author: TheRuler8510
author_rank: Regular Contributor
timestamp: April 08, 2015, 11:14:04 pm
content: Quote from: zucca on April 08, 2015, 04:46:25 pmOops, I forgot the pic.Any idea what is the value of the resistor that the red arrow is pointing to? It is also known as R144.Thanks

author: Tronto
author_rank: Contributor
timestamp: June 10, 2015, 12:00:46 am
content: QuoteDid you find the value of R144? What caused it to blow? Did you get your PS up and running?

author: TheRuler8510
author_rank: Regular Contributor
timestamp: June 12, 2015, 04:36:11 am
content: Quote from: Tronto on June 10, 2015, 12:00:46 amTronto,I never got it running. It is sitting with another 8 stalled repair projects...one day I'll get back to it.I never got the resistor value. I suppose I will have to experiment to find out.If anyone knows the value of R144, please let us know--or a schematic.Regards,