My question concerns a future research project in electrocoagulation (water treatment) I am planning right now.

I will have a lab power supply connected to two (or more) plates in water. The operation will run in a galvanostatic mode, meaning I want to have a constant current through the system as one of the major outcome determining factor is the charge density through the plates (e.g. \$mA/cm^2\$). The plan is to procure a lab power supply that can supply up to 30 A, since that is at the higher end of the range I want to test. My measuring probes and the power supply will be programmable, meaning I have the possibility of centrally controlling the electrical inputs and the data collection of experiments from my computer.

One thing that I want to test is reversing the polarity of my electrodes to counteract electrode passivization, i.e. switching the anode and cathode during the experiment. I would like to do this in a programmable fashion as well. For example, either at timed intervals or maybe when a certain voltage drop has occurred due to the increased resistance from the passivization.

Given that I have all required signals connected to the computer, what would be the way to solve my problem? The programmable side will not be an issue for me, I am mostly interested in the best way to solve the problem.


  • Switching circuit should be able to handle up to 30A passing through the switching side.
  • Programable

Thanks in advance!


1 Answer 1


Use a H bridge / motor controller (where your anode and cathode replace the motor).

enter image description here

Image source: multiple motor h bridge?

  • \$\begingroup\$ Would it work interchangeably? A DC motor would be an inductive load and the between the electrodes in my circuit it would be a resistive load. I've searched around a bit, have not found an H bridge/ motor controller board that can handler higher currents yet. Also searching around for high current DPDT programmable switches, but I can't find any of the shelf products. \$\endgroup\$
    – Aquapuer
    Nov 29, 2019 at 10:33
  • \$\begingroup\$ No, not interchangeably, but one way: if it can switch a inductive load, it can also switch a resistive load. But not necessarily the other way around \$\endgroup\$
    – Huisman
    Nov 29, 2019 at 10:52
  • \$\begingroup\$ @Aquapuer Searching internet for "30A brushed motor controller" yielded e.g.: robotshop.com/en/medium-power-motor-controllers.html or nl.rs-online.com/web/c/automation-control-gear/… (nl.rs-online.com/web/p/dc-motor-controllers/7736844). These are suggestions how to search, I didn't go into details if it fits your application. \$\endgroup\$
    – Huisman
    Nov 29, 2019 at 10:56
  • \$\begingroup\$ Ok, thank you. I think you've pointed me in the right direction. \$\endgroup\$
    – Aquapuer
    Nov 29, 2019 at 12:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.