Adjustable Dual Polarity Power Supply

Hi Flemming,

There are schematics (and board CAD files as soon as I upload them - let me know if you need them anytime soon) for a dual-rail supply here:

Building a Linear Power Supply Module

It is fixed voltage, but can be made adjustable by swapping R2 and R6 out for variable resistors (and put a small resistance in series with them too).

If you need some help figuring out the values, let me know.

It is only a 200mA dual rail supply, or optionally 3-rail.

I created it for future op-amp and headphone amplifier projects, so it was intended to be a fixed rail supply.

If you wanted something with through-hole components, there is nothing wrong with a LM317 supply by the way, it will still serve you well.

I have an old homemade LM317 supply myself (I used a couple of LM317, for dual output), and I still use it.

Photo here next to a paperback book for size comparison. I didn't do a great assembly job.

Also if you search for jw0752 content he has blogged about some power supplies he has constructed, so you can see some ideas for how to build them.

Hi Flemming,

There are schematics (and board CAD files as soon as I upload them - let me know if you need them anytime soon) for a dual-rail supply here:

Building a Linear Power Supply Module

It is fixed voltage, but can be made adjustable by swapping R2 and R6 out for variable resistors (and put a small resistance in series with them too).

If you need some help figuring out the values, let me know.

It is only a 200mA dual rail supply, or optionally 3-rail.

I created it for future op-amp and headphone amplifier projects, so it was intended to be a fixed rail supply.

If you wanted something with through-hole components, there is nothing wrong with a LM317 supply by the way, it will still serve you well.

I have an old homemade LM317 supply myself (I used a couple of LM317, for dual output), and I still use it.

Photo here next to a paperback book for size comparison. I didn't do a great assembly job.

Also if you search for jw0752 content he has blogged about some power supplies he has constructed, so you can see some ideas for how to build them.

There's loads you could do to make it more interesting than just an LM317/LM337 based supply depending on how flexible you want your supply to be.

For example, if you want to increase the efficiency you could create a switching regulators for the positive and negative rails and then use the LM317/LM337 as a post regulator smooth out the output by rejecting the switching noise.

If your output will be a symmetric voltage then you could experiment with something like a flybuck topology to generate the +ve and -ve rails from a coupled inductor placed in the usual output inductor location of a standard buck converter. Again use the lineatr regs as a post regulator to smooth the output.

There's so many choices you could make which would make a fun power supply build. What are your required specs for this?

Best Regards,

Rachael

Thank you for you reply

What i am looking for is 1 knob adjustable, 0 - +-15 volt ,05 -1 amp. output, I don't expect professional data, a little noise don't matter much at this point.

Flemming