Retrofit a DC PSU with Digital Potentiometer, feasible?

Hi guys

How feasible would be to wire a Digital Potentiometer to one of those mechanical POT found on a DC power supply? I use this PSU for anodizing aluminum and would like to automate the calculation for Amp/spf using an Arduino preferably.

If all possible, how would I wire this up to the exiting 5V/Gnd/Wiper pins on the external PSU? Does the Grn needs to be shared between Arduino and the PSU, how would that work.

below is the PSU I'm having, I just need to control the amp POT really. Thanks for any heads up on this little puzzle.

Why not get an inexpensive "Programmable" Power Supply, like the Korad KA3010P, Siglent SPD1305X or Rigol DP712?

I have a Korad KA3005P that I can control with an ATmega through it's DB9 connector.

You are lost if you cannot answer your questions yourself, and also don't have a (link to a) circuit diagram of your PSU :frowning:

A simple solution would connect a servo motor to the pot axis.

@Perehama, thanks for the idea. Possibly the best way forward is as you've clearly said; get a prog PSU. Unfortunately my limited budget prevent me from doing so, beside I require roughly 20~25CC(amps) so those PSU don't come cheap :frowning:

@DrDiettrich haha, I'm desperate, not lost (I'm learning though). I have to give it to you, that servo idea is brilliant! That PSU current knob is just a plain 10k pot and was wondering if I could just quickly hook up one of those Arduino's 10 kOhms I2C Digital Potentiometer on those 3 wires, or how difficult this would be not having the schematic of the PSU.

Thanks for the responses guys, cool forum!

There are two problems with "digital potentiometers", more accurately described as "digital volume controls" because that is their primary purpose.

One is their potential power dissipation, which is almost nothing, so if the voltage and current through the potentiometer in question would lead to heating, then it would not be suitable.

The second, more relevant in this situation, is that with rare exception, they control only voltages within the range of their digital supply voltage, presumably 5 V. So if all terminals of the control potentiometer in question will always be within that range, it is OK, but on a DC variable power supply, I would have my doubts.

I have to give it to you, that servo idea is brilliant!

Perhaps, but more to the point a logical move.
First thing that came to mind for me also............. :o :o

All you have to do now is work out how to do it. :slight_smile:

Microchip makes a 36 volt capable digital pot, the MCP41HVX1

Maximum wiper current is 12.5 ma. To be sure it would work, you’d either need a schematic of the unit or open it up and measure the actual pot voltages and wiper current.

Thanks for all your ideas guys! Super kind, I obviously need help LOL Got a feeling I'll get this working eventually and an Arduino MCU is going to automate the CC/AMP, temp/heaters, pump and timers via relays. I'll show and post the progress for sure.

@WattsThat - wow good find, thanks man. I'll have a go at the unit tomorrow and check on mA and V from the pot and see if this doesn't exceed what's available to us. 12.5 ma doesn't sound like much... let's see. Certainly max at 5.7'ish vdc, already checked that part.

@bluejets - well, a mechanical solution might be the 'fix-it'. I'd like to try a Digital Vol Ctrl (thanks for the clarification Paul_B) before getting parts CNC'ed or 3D printed. Regardless, this is what it would look like using the cheapest, smallest, lightest and most accurate stepper I could find (2048 steps/rev). Total assembly weight is 64.7grams and sits on the pot's threaded mounting shaft.


Something like this...

lol, hidden in a cabinet where nobody can see, doesn't look half-bad, errr :confused: I like the idea Dr, but damn I'd like this digital pot idea to work instead. I hope the current on this pot is less than that of what's on the market (i.e. < 10~12mA).