I was experimenting with electroplating copper to steel.
I first tried a 6vdc battery charger, which was too high volts.
Then I tried an ATX power supply using the orange 3.5 v wire, and it is also a little too high, I get a lot of hydrogen gassing off of the steel.

I have a lot of 5 watt 100 ohm resistors. Could they be used as a voltage divider?

 

I have a lot of 5 watt 100 ohm resistors. Could they be used as a voltage divider?

Probably not..what current does the process draw ? Is the current fixed or does it vary ?
Starting with simple, if the current is fixed, a small series resistance in series with the 3.5v supply should do it. or some series silicon diodes - allow about .6 Volt drop for each one introduced

 

some Atx 3.3v rails use a tl431 regulator on the 5 v rail,with a fet, otherwise they have straight outputs on the pulse transformer, i modified an atx to variable and the 3.3v rail went down to 1.8 to 6.5v,