Panel Mount Voltage Regulator / Knob

[Jeremy]

What sort of voltage and current range are you looking for?

What I think you need is something like an ordinary lab bench supply. These often come up on ebay for a reasonable price.

Alternatively you can build one easily enough. I have three or four variable voltage bench supplies that I've built, the most recent being one to power my home made capacitive discharge battery tab resistance welding machine (see pic below - it's the silver box on the left with the digital voltage readout).



Jeremy

[Robin Hewitt]

For my DC suds pump speed control I used an LM338T, just google for LM338 and get the data sheet with circuit diagrams.

Up to 5 Amps, needs a few extra components, but with a bit of jiggery pokery you can solder them on to the pins and enclose with shrink wrap.

Bit of an industry standard, costs a quid.

[irving2008]

For my DC suds pump speed control I used an LM338T, just google for LM338 and get the data sheet with circuit diagrams.

Up to 5 Amps, needs a few extra components, but with a bit of jiggery pokery you can solder them on to the pins and enclose with shrink wrap.

Bit of an industry standard, costs a quid.

LM338 is good device for a fixed supply, but not ideal for a variable unit unless you have a big heatsink. if you want 0 - 25v off a 30v supply at 5A then you are outside its thermal characteristics - it can dissipate 25W max so thats 5A at 25v output, dropping to 1A at 5v output. Has the advantage of simplicity tho with only 5 other parts needed (excluding bridge rec and smoothing cap)

Although slightly more complex (as in needing 6 more parts) a switch mode supply based on LT series devices needs no heatsink and gives variable current limit as well as voltage.

A similar spec bench supply on ebay is about £60 so by the time you bought the bits and made it up and boxed it for safety its marginal to make them really... except for the fun/satisfaction of knowing you did it yourself.