19 replies to this topic

[Arthur Brown]

I think we can all get an old but functioning ATX PSU from an expired PC or a computer fair so simply spacing the electrodes to keep the current within sensible regions is the cheap way.

While a MOT might be rewindable to give low volts they usually are of little use long term at near their rated power because they are designed to run at full power for 10 minutes typ cooled by a big fan. Now if you can rewind one to say 15v then get the control by driving it off a variac then there is an easy answer, but keep the trans out of the corrosive mist from the cell.

[CCH Concepts]

variac's cost hunderads of pounds and rewinding transformers is easier said than done, depending on the type.

[frosty90]

Hi all,
Just thought I'd put in my experience here: MOTS are very usefull because of their cheapness. They are pretty crap as they come though. they are manufactured with the absolute bare minimum copper, not enough turns on the primary, which leads to saturation, and hence the massive currents and heating even when idle. If you have access to suitable wire to rewind them though, they are quite usefull: I have rewound a few in the past for various applications, and what I did was this: Use the secondary as the primary, to keep the thing out of saturation you need around 500 turns on the primary, even doubling the defult number of turns helps hugely. Ive found that most tend to start saturating at about 100 volts input. Most secondaries are around 1500 turns, so use this as the 240/220 side, and wind your own secondary for the desired voltage. With more primary turns they will run much cooler, I havnt even needed forced air cooling, running at about 500 watts. For most MOTS the core dimensions really need at most around 1 volt per turn from memory. But as they come they are made on the cheap for low duty cycles.

Be careful though using the secondary as the primary, usually the secondary is connected to the core, you'd be best to remove this connection, you dont want the core to be live. Another possible problem with this is that because of this, the inner paarts of the secondary arent insulated from the core very heavily. Ive never had trouble with 240 on the secondary disconnected from the core, but be sure you are confident and have experience with electricity before attempting this.

One problem though is the cores are usually welded, and unless you weld them back together after re-winding, they will be rediculously noisy. But you could always build an adjustable clamp for an adjustable air gap for current control. Just be sure to remove the magnetic 'shunts' when you cut the core.

Cheers,
Jesse

[Arthur Brown]

For most people who want to do electrolysis a computer ATX psu is cheaply had from a computer fair or a surplus PC. This should yield a 5v output of about 25 amps with all the regulation and rectification and smoothing all sorted out.

MOT are designed for short term use with forced cooling, they may suit some purposes but not electrolysis for days at a time.

There is a tutorial on youtube on turning a computer psu into a lab psu.

Skilled searches on ebay often yield adequate PSUs but the search terms can be variously difficult. There was a 130 amp programmable one recently.

[Bonny]

Computer power supplies work great for chlorate cells. I produced over 20kg with one and no problems. The one I have is rated for 20A at 5V, but I was running ~22A without any trouble. See here for more info:
http://oxidizing.110...orate/cpsu.html