Decent, inexpensive bench power supply?

Kind of ruins the “cheaper than a supply that costs 60% more” angle, though :grinning: (but ok, you get more 12 V amps).

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Gratitude for responses. Buying two is still pretty dang cheap and doesn’t have the unnecessary 5v rail. Open to other suggestions?

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@ehisforadam did not have success with the nozoïd design.

I took a gamble on the Nozoïd design too, since those modules are super cheap.

An Aliexpress seller seemed to have one with all the proper characteristics, but it turns out they sent me a revised revision: JM21RP LM2596S, HW-411, despite advertising older specs.

Sadly, I’m not getting it to work. When wiring two supplies as indicated, my bench PSU goes into CC mode and drops the voltage, which seems to indicate it’s shorting.

I saw online a different way to wire them up to get negative voltage:

I have not tested it, but even if it worked, I would not trust the resulting contraption too much.

“Super cheap” is more a warning sign than a virtue especially when it comes to power supplies. Trying to cheap out on power is almost always a mistake.

@ehisforadam reported three Nozoïd supply modules blowing up before he gave up on them, link above and this:

Apparently no synth modules (or users) damaged in these disasters, fortunately, but I still would not let one of these things anywhere near my synth.

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Since this topic’s come up again, I’ll mention I bought this about a year ago:

These seem to be available new for $170 to $200 or so. I bought mine used from here:

They’re not showing a price, instead a “request quote” button, but when I bought mine it was $60. A steal. It was in excellent condition, just a bit of minor cosmetic discoloration, working perfectly. Two variable voltage 3 A supplies (can be set up as ±12 V — tie one side’s negative post to ground for +12 V and the other side’s positive post to ground for -12 V) and a fixed 5 V supply, variable current limit.

Same vendor has a lot of other DC supplies, used and new; looks like you have to request quote on any of the used ones.

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Oh wow, $60 for a HY300F-3 is awesome :laughing:

I use two of these Korad KA3005P – which is (P)rogrammable via USB/RS232: Korad KA3005P Labornetzteil, 109,00 € - Welectron The KA3005D is non-programmable and around 20 Euro cheaper. I paid 90 Euro a couple of years ago for the P-model, but now they got a bit more expensive (around 100-120 Euro), but it’s a really decent PSU with very good performance for the price. Here is an old review from Dave/EEVblog:

I really like the display which has basically zero latency (in contrast to some cheap PSUs with LCDs). The PSU can be calibrated for both the voltage and current limiter and the memory feature is also very handy.

There is also a combined one (KA3305P) for 230 Euro, which contains basically two of these linear PSUs and a third one with fixed voltages (3.3V and 5V): Korad KA3305P+ Labornetzteil (Sicherheitsbuchsen), 269,00 € - We but I prefer two distinct devices in case I need to put one somewhere else :wink:

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I realize I posted about those deprecated Nozoïd design in the wrong thread, haha, since they were mentioned in multiple ones and this was the most recent mention.

But yeah, I also tried another similar module I forgot I had, the correct board without the HW-411 REV, but a JM08RP LM2596S-ADJ. That one too doesn’t work, just draws as much current as it can. Those modules are definitely too much trouble even for a small test rig. You need the exact specific version from vendors who frequently switch components.

Speaking of bench power supplies, when I bought mine, I found it much more affordable to simply buy two single-channel supplies instead of a dual-channel one, when I researched the question back then, I didn’t find any reason not to go this route.

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I requested a quote from them for the supply + shipping to my UK address.
image
You really have got a bargain on your hands.

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Sell ya mine for $695…

(Mastech has new ones for $170. These guys… I dunno.)

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Here’s another approach that I hadn’t considered, admittedly quite DIY - but I think I have an old ATX PSU hanging about not doing anything:

https://hackaday.io/project/184598/instructions

Edit: https://www.electronics-tutorials.ws/blog/convert-atx-psu-to-bench-supply.html has some more details

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Kind of an old thread, but I’m getting into building modules and I wanted a power supply before building anything.

Found these two adapters that output 12v DC 2A each one, and I was wondering if it would be of any use for a DIY PSU.


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An erroneous posting…

Maybe, but be aware most wall warts have little or no regulation, so if you want a reliable 12.0 volts look elsewhere.

Many circuits will work OK a few volts up or down but it varies.

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Simple PSUs are the MFOS’ simple one operating from a 9VAC wall wart. Guess it’s the same kind Soundtronics use (in the MIDI Ultimate.

I will eventually order a SMPS module from China, but fear I will get tons of spikes and shlt: Dual smps module from Chian.

I use an ATX power supply I pulled out of an old desktop PC. I’ve got a breakout board from Amazon that gives me proper terminals to connect to (though the binding posts it came with weren’t ACTUAL binding posts, ie you couldn’t clip/insert anything to connect).

It works well enough–it’s got ±12v, 5v, 3v3 and ground, and the breakout board is fused, so that’s cool. The +12v rail only manages about 11.85v but I figure it’s good enough for government work.

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I use this for all my diy stuff. Just wire the negative lead of #1 to the positive lead of #2 and the junction of the pair becomes ground. The positive lead from #1 is +12 and the negative lead of #2 is -12. I put like ten or twelve modules for ever pair like the ones in your pic. Any more than that and you get some negative results. it all depends on how much current each module needs to function properly. I usually discover this if random modules start to act strange after plugging a new one in. At this point I just wire up a new pair of walwarts just like yours and it has worked like this for about 8 months and I’m still adding on. I’ve got 3 pairs filled up and working on my fourth, and as I’ve said I notice the need for a new chain at ten or twelve modules each ( i have twelve on one, ten on another, twelve one another and the fourth…) Keep in mind what @analogoutput has to say, because I do have some strange results to account for in my recent but eventful diy journey, although they happen with my regulated bench supply when testing as well as in the rack.

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Thx for the advice (thx @analogoutput too). I was thinking in wiring the thing in another way, but read your reply and checked a lil schematic and my thoughts didn’t make sense anymore lol, but yeah your wiring should work.
Also, yeah I kinda doubt it is a reliable PSU, but i’m thinking for a quick solution and I’m not planning on running a lot of modules on it (it’s not like I have any anyways). I might try the ATX thing if I find a PC power suply lying around.

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Just be warned old ATX supplies can have some bad ripple, maybe things have improved on newer generation PSU’s

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Oh, fair point. I haven’t looked at the power output on a scope, only on a multimeter. I’ll look into that. Thanks!