Decent, inexpensive bench power supply?

Can someone recommend a simple, inexpensive bench power supply for prototyping and testing Kosmo and Eurorack modules? I’m in the US so if someone has an amazon link they want to share or the name/brand of one they can suggest I would appreciate it!

How topical! Last week I ordered one of these:


It came with a dented bottom so I had to take it apart right away to get it to sit right, but it seems good. The problem is I got it to replace one that doesn’t have the rail-to-rail connections, but I can’t figure out how to get it to put out -12 on the black, 0v/Gnd on Green and +12 on red. I think it may take a shunt between red and black or something. Does anyone know the answer to that one? (@fredrik, lookin’ your way bud!)

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Unfortunately I think you won’t be able to get -12v on this supply. Someone else will confirm that or hopefully not /-:

I’ve heard good things about the Frequency Central kits, which are sold as circuit boards. You need to get a 12V AC (NOT DC) “wall wart” supply and solder a few inexpensive components onto the supplied board. They sell a few different versions, but the design is essentially the same. Sam has a case construction video that features a few of them. It was the first of his videos I ever watched.

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The meanwell rt-50b is also a simple option for a bench supply. For 15 euros, hard to beat. You just need to put it in a small enclosure to be safe on the mains side. If you don’t know how to wire mains, don’t do it, the voltages in there could kill you. That’s why you need an enclosure :slight_smile:

In europe, buy here : https://www.tme.eu/fr/details/rt-50b/alimentations-encastrables/mean-well/

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I didn’t know you could get one for so cheap.

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@Bitnik What’s the BOM on those?

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A third option is to connect two 12v power supply together so that they provide the required voltages. I didn’t test it but it seems to work fine. Here is a build :

Note that the important part is the schematic on how to connect the two supplies together. I think it should work with other 12v sources. (you could for example connect 2 bench supplies together to make the required voltages)

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Thanks for the info. I really don’t want to mess with mains or to try and build my own. I have a lot of electrical knowledge when it comes to homes, but I’m new, obviously, to synth circuitry. Knowing that, is there a bench supply that you or anyone else can recommend that does provide -12V?

If not, then perhaps I will get a cheaper, simple supply like the one @Maxhirez suggested for some of the other projects I want to test and then put together another FS module to use for testing euro/kosmo modules. (Or look into building the one that @philippejadin recommended.)

PS: I have discovered the frustration of submitting a Tayda order only to find the next day that I forgot to add something to my order. (!#%^%!!!)

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Looking a bit more on tme.eu, there is this one which seems very interesting : https://www.tme.eu/fr/details/gp50a13d-r1b/alimentations-de-bureau/mean-well/

it has an enclosure so you only have to deal with low voltages.

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For the Frequency Central stuff, you can go here:

https://frequencycentral.co.uk/product/fc-power/

There are a couple of alternative board options, such as one that features space for a bunch of EuroRack connectors and another that provides space for various connectors. With appropriate choice of components, this can serve either a 12V or 15V bus.

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The name says it: “single output”, you can’t get both +12V and -12V out at the same time, you would need two of those units to do that.

If its applicable, I did a BOM thread over here for the microbus:

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@antoine.pasde2 Awe, dammit! That’s not the first time a specific search on Google has sent me to Amazon and screwed me with results. Thanks for pointing that out! The question is now, do I send this back and get a double, or do I just plug my old single into the same power strip and banana to ground? Fire hazard? :man_firefighter: :woman_firefighter:

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As you mention that it was damaged when you received it, you have a good excuse to return it, but if you do keep it, I don’t see any danger in using it along side another similar one with a floating output.

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I use one of these, running off the frequency central microbus!

https://www.thonk.co.uk/shop/transient-breadboard-kit/

hope this helps :+1:

seano

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Funny I was just thinking about designing something exactly like that last night, for modular breadboarding.

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I’d love to see what you come up with.

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Look for used on sites like EBAY. Bench Power supplies aren’t cheap to begin with, usually they are made for labs and repair shops, and they are just solid and heavy as rocks, because they are going to have a lot of use.

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Narh, if it is +12V and -12v, it is just one that can deliver AC, in which is a standard feature for most Bench power supplies. If you you want to control more than just voltage, like frenquency and waves you might add oscillator to the setup.

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