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SMPS to Bench Supply - Help Answered

Hi There,

I want to make a bench supply using my old SMPS. I have seen many tutorials and I've some questions which I need assistance with.

My SMPS says 12 V @ 25 A, 5 V @ 10 A and so on..

In tutorials I see people soldering all the same colored wires to one output 12V, 5V, 3.3V and so on. So, if we do that and I connect a 12V device that operates @ 2A or 3A  to the 12V ouput @ 25A in SMPS that we make, will it fry my device. If so, how do we control the current to supply 12V @ 2A only.

I want to make a bench supply with below specifications. Can I do that?

1. I want 2 to 3 outputs each for 12V, 5V and 3V.
2. I want to regulate the current for each such socket mentioned in clause 1 to 1A, 2A, 3A and so on..

Is that possible? If so, how any instructions?

Avinash B


The forums are retiring in 2021 and are now closed for new topics and comments.

3 years ago

Whatever device you plug in will take the amount of current it needs to operate correctly.

If you plug a 12 Volt 2 Amp device in to a 12 Volt 100 Amp power supply it will still only use 2 Amps. The only time any device will use more current than it should do is if it is faulty with something like a short circuit or incorrect voltage. If you plug a 12 Volt 2 Amp device in to a 12 Volt 1 Amp supply then you will have problems because the device will try to take 2 Amps from the supply that it needs and probably blow a fuse or other component in the supply.