Toroidal Transformer High Current Output

high-currentinductancepowerpower supplytransformer

Can a 28-0-28 amplifier toroidal transformer like this be practically used as a high current supply at low voltages? I plan to put a couple of turns of 4 gauge wire through the centre. I want to use the power supply for heating metals to red-hot temperatures fairly quickly, so the current output has to be pretty high. I would use the stock primary.

Best Answer

You may be able to do that. A better setup: using a microwave oven transformer (MOT) from an old microwave, with the secondary removed, and a new secondary from a few turns of very heavy gauge wire (as heavy as would physically fit). This tends to produce on the order of 1500-2000VA, for example 200A at 10V with ten turns, or 1000A at 2V with two turns, depending on the MOT. One especially nice feature is the magnetic shunt which regulates the peak current, unlike your toroidal. That means the current is appropriate for the primary, ie it won't trip the mains breaker; however it does NOT mean the new secondary won't melt down :) Check this out: or just google "microwave oven transformer welder" for lots of examples.

Do be careful, as this is a mains powered circuit. It is good to put it in a grounded metal box, with a safe way to connect and disconnect from the mains (a switch rated for mains voltage and heavy current). The hazards on the output side are less about electrocution and more arcing and fire. Needless to say, when shorted, this produces enough heat to melt itself down, as well as potentially set nearby stuff on fire. This kind of device is very hazardous, you have been warned.