Electrolysis using an old computer power supply

[BobL]

I've done my electrolysis in the past using an old battery charger. Since that charger disappeared I bought myself a new one and of course the new ones won't work by themselves (they will work with a battery in parallel with the charger) to drive an electrolysis tank so I thought I would give a computer powersupply a go as a source of electrickery. It works but it needs a little tweak which you may not be aware of. I'm also writing this whole procedure for newbies so please excuse me if you are already a gun at electrolysis.

Firstly I had to make a new bath because what I had to derust was this and all I have done in the past i small stuff that would fit in a bucket.
Attachment 167450

New bath
Attachment 167451
The tank is an $8 50L plastic box from bunnings - it doesn't look like it will last too long. The object sits on half a polyethylene cutting board with lots of holes drilled in it and the PE sits on two pieces of angle to keep the object out of the sludge. There are 4 anodes made from pieces of 3/4" steel water pipe located around the tank to spread the electricity and make for a more effective system.

Power supply
Attachment 167452
The reason for the optional disc drive will be explained shortly.

To get these power supplies to fire up, the only green line coming out of the power supply has to be shorted to any black line. You can leave the short in from here on and just use the power switch on the power supply.
Attachment 167453

The power supply will also only stay on if it has a load - this is OK once the electrolysis bath is fully set up but to test line voltages the power supply needs to be driving something so I used an old floppy drive. A DVD or HD or a light globe will work equally as well.

The highest current lines from a PC power supply are Yellow (12V, typically 15A) and Red (5V, typically 30A) - Pick any yellow and black line and attach some extensions and connect the yellow line to the anode(s) and the black line to the part. If you connect it right scum will form on the anodes, if not just reverse the connections.

For a conductive salt I use the well know Sodium Carbonate (washing soda) I got mine as foot bath salts from coles. $4 for a 1 kg bag - it already has some water in it which makes it easy to dissolve. I made a concentrated solution of the sodium carbonate by dissolving about 1/2 of the bag in 2 L of hot water in a separate container. I then filled the bath to near full with water and slowly added the concentrated Sodium Carbonate solution to the bath and watched the ammeter till it was reading about 4 A.
Attachment 167454
After a while the anodes gunk up the current drops so they need to be cleaned. I need to get some carbon rods to set this up more permanently and reduce the cleaning of the anodes.

My guess is the tank has 40L of liquid and I put ~250g of the original salt into the bath so that is 6.25 g/L. Any more than this and the power supply may trip out. you don't need a meter or disc drive - just use 6.25 g/L and make sure that scum forms on the anodes and you're good to go.
Attachment 167455

[Stustoys]

Nice going Bob. Got any pictures of the result or isn't it cooked yet?

If you don't like the drive, the power supplies I have played with only need a small load on thee 5V line. I used torch bulbs but as I moded the supply to get a few more V's out of it I kept blowing blubs so I've gone back to using an old drive as well lol.

Stuart

[BobL]

Nice going Bob.

Cheers ST

Got any pictures of the result or isn't it cooked yet?

Not yet - it's still cooking - how long do you reckon something this big will take? - I've never done anything bigger than plane or chisel blades before.

If you don't like the drive, the power supplies I have played with only need a small load on thee 5V line. I used torch bulbs but as I moded the supply to get a few more V's out of it I kept blowing blubs so I've gone back to using an old drive as well lol. Stuart

I have a couple of 50W 50 ohm resistors that I guess I could use.

[Stustoys]

Not yet - it's still cooking - how long do you reckon something this big will take? - I've never done anything bigger than plane or chisel blades before.

I've have no idea at all. I'm yet to try this, although it does look interesting.

I have a couple of 50W 50 ohm resistors that I guess I could use.

That should do it alright. I really should do it myself as I now use the supply to run the LED lights on my mill, the drive is pretty noisy and bugs me sometimes.

Stuart

[BobL]

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as I now use the supply to run the LED lights on my mill, the drive is pretty noisy and bugs me sometimes.

Stuart

That's an excellent idea, we have a skip full of old PCs at work so I'm gonna get myself a few before they go, or I could just wait until the next hard rubbish pick up!

[azzrock]

thanks for putting this up. i had no idea you could do this i thought you had to use harsher chemicals.

[Avery]

ummm, I hope you have the current flowing the right way round, The negative should be connected to the workpiece and the positive to the sacrificial anode.

Positive to anode, negative to cathode.

Are those copper waterpipes that you are using? Does that work?

[Cliff Rogers]

Yup, it is a bit confusing, he did say....

connect the yellow line to the pipe and the black line to the part

But from the pics, it looks like he has done it the other way around.


This article is worth a read.
The science behind electrolysis

[BobL]

ummm, I hope you have the current flowing the right way round, The negative should be connected to the workpiece and the positive to the sacrificial anode.

Positive to anode, negative to cathode.

Yep well spotted! about an hour into the process I noticed the water pipes weren't scumming up and I knew something was wrong so I reversed them before there was any real damage. I have only just managed to edit my post above accordingly.

Are those copper waterpipes that you are using? Does that work?

They are just slightly rusty water pipe.

[Cliff Rogers]

You must have fixed it while I was looking at it 'cos the pictures didn't match the text.

[BobL]

You must have fixed it while I was looking at it 'cos the pictures didn't match the text.

Yep only just edited the post.

Oh yeah and thanks for the link.

[nadroj]

After a while the anodes gunk up the current drops so they need to be cleaned. I need to get some carbon rods to set this up more permanently and reduce the cleaning of the anodes.

Thanks Bob.
That's interesting about using carbon rods. It is a nuisance having to clean or replace the electrodes. Where could one get some rods?

Jordan

[Master Splinter]

Great thread!

I'll just be an OHAS geek and mention that plenty of ventilation is a good idea - oxygen and hydrogen are produced at the anode and cathode, at the perfect mix for extremely rapid, energetic and noisy re-combination if ignited...don't inspect your tank while takin' a ciggie break!!

[Avery]

Great thread!

I'll just be an OHAS geek and mention that plenty of ventilation is a good idea - oxygen and hydrogen are produced at the anode and cathode, at the perfect mix for extremely rapid, energetic and noisy re-combination if ignited...don't inspect your tank while takin' a ciggie break!!

All true, but the amounts of gas released are miniscule. The hydrogen dissipates very quickly indeed. If you tried hard you may be able to get a bubble to go "POP", but you would have to try hard.

[BobL]

Thanks Bob.
That's interesting about using carbon rods. It is a nuisance having to clean or replace the electrodes. Where could one get some rods?

Jordan

Welding shops apparently have them.