Sciencemadness Discussion Board - Electrolysis power supply capacitors

Electrolysis power supply capacitors

thesmug - 11-4-2014 at 17:24

Earlier today I modified an old atx power supply as an electroplating/electrolysis power supply. Everything works fine, but the two input capacitors make a high pitched whine (the sound of a capacitor discharging, obviously) that pulses very rapidly. I have concerns I might damage the power supply so has anyone else had this? If so, did it do any damage and/or did you find a way to fix it?

[Edited on 4/12/14 by thesmug]

elementcollector1 - 11-4-2014 at 18:59

Capacitors do that sometimes - apparently it's supposed to happen? This can be smoothed out by simply adding more capacitors.

thesmug - 11-4-2014 at 20:30

Ok, good to know. It's a simple modification and adding more capacitors would be really hard, especially space wise.

elementcollector1 - 11-4-2014 at 21:16

How is it set up? I've been using either 12V or 6V batteries, and these don't work at all (even when chromate is added in minute amounts), possibly because they run out so quickly. Permanganate does nothing either...

thesmug - 11-4-2014 at 21:45

It's a modified ATX computer power supply made in almost exactly the same way as woelen's at http://woelen.homescience.net/science/chem/misc/psu.html

Bert - 12-4-2014 at 05:28

What are the type/ratings/physical sizeof those caps- Electrolytics?

Do you absolutely need to keep the circuitry in the manufacturer's chassis?

Zyklon-A - 12-4-2014 at 05:53

I hate using batteries, why not just buy a fixed PSU? Here, there are cheap PSU's of any voltage/amperage combination. You just have to find the one you need.

[Edited on 12-4-2014 by Zyklonb]

thesmug - 12-4-2014 at 09:50

@Zyklonb, my setup is essentially that. @Bert they are 470uF 200v electrolytics, about 4cm tall and 2cm wide. I think it's almost absolutely necessary to keep the manufacturer's PCB intact since it's a very complex circuit.

hyfalcon - 13-4-2014 at 03:29

You can keep the circuitry intact, just take the circuit boards out of the metal housing they are mounted in. That will give you more room to add bigger, taller caps if necessary.

Bert - 13-4-2014 at 05:18

If no room in original chassis?

Unsolder the leg wires of the electrolytics, solder in some lead wires in place of these.

Attach a pair of larger electrolytic caps to the leads, outside original chassis. Be careful to follow same polarity when hooking new caps up.

thesmug - 13-4-2014 at 06:55

I will try the above suggestions. Thank all of you very much.

aga - 18-4-2014 at 11:40

Quote: Originally posted by thesmug

the two input capacitors make a high pitched whine

Sure it is the caps ?

Normally it is mechanical instability in the chopper transformer.

When the sound appears to be coming from another place, it can be a component resonating with the switching frequency at some sub-harmonic or other.

Easiest fix is hot melt glue all over the places where you think the sound comes from.

That usually dampens or stops the maddening high-pitched whining noise.

The Volatile Chemist - 18-4-2014 at 11:49

Quote: Originally posted by aga

Quote: Originally posted by thesmug

the two input capacitors make a high pitched whine

Yup

I use a Computer PSU, but sciplus.com has some awesome ones I'd like to get.

Bert - 19-4-2014 at 06:04

Cheap transformers ARE noisy-

In this regard it is important to notice that a noisy transformer means that: a) The transformer is badly constructed, or b) That the transformer is forced to operate in a magnetic region close to or at core saturation.

Texium - 31-5-2014 at 07:24

I was planning on putting together an electrolysis setup, and I was wondering what the proper voltage/amperage combination would be. I know very little about electricity and just don't want to use batteries anymore. Would a simple AC/DC power converter from Radio Shack of the proper voltage/amperage be suitable, or is that a really stupid and noobish idea?

markx - 2-6-2014 at 03:16

Quote: Originally posted by zts16

I was planning on putting together an electrolysis setup, and I was wondering what the proper voltage/amperage combination would be. I know very little about electricity and just don't want to use batteries anymore. Would a simple AC/DC power converter from Radio Shack of the proper voltage/amperage be suitable, or is that a really stupid and noobish idea?

Everything depends on the purpose of your experiment. But usually electrolysis power supplies are designed for low voltage (around 5V dc) and high amperage (>10A). For example if you plan to perform electrodeposition of metals, you can probably make do with a rather simple and low amperage power supply from just about any radio parts store or a salvaged power supply from an old machine (e.g PC power supply). Electrodeposition is usually performed at low current desities and therefore the power supply is not working under a high load. The opposite case is with electrosynthesis like the production of chlorates, perchlorates, permanganates, etc.....there the stress is high as usually strong currents are forced through the cell and one needs a beefier supply. Also a means of controlling the current and monitoring the amperes and applied voltage is very beneficial. This can be performed with a simple dc PWM module (pulse width modulation) and simple volt+ampermeters that operate on the same power supply. All of these can be had for a very good price on Ebay or from your local electronics store.
If one needs a specific regime for the electrochemistry ( constant current, constant voltage or constant power) then also these modules can be bought in a wide variety on ebay. LED drivers offer a pretty good solution in that case and are quite affordable.
The options are plentiful....but for us to offer more detailed suggestions, you have to first decide on what area of electrochemistry you wish to explore and what will be the scale of the experiments ( a shot glass sized cell with a few square centimeters electrode area or a bucket cell with plenty of electrode size).

arkoma - 2-6-2014 at 06:24

I use a crappy old 250W PSU from an ancient e-Machines desktop, drawing so much current the fan kicks on high. No probs so far and been using it a while

@AGA--excellent tip

The Volatile Chemist - 2-6-2014 at 06:36

If you use too little sized electrodes or too little soltn., or too little space btwn. electrodes, things heat up, but that's about it.