If you get
really creative, you could rewind a transformer to give the 24 volts you need. The first, and most important, step would be "
does it need regulated power"? It sounds like it doesn't, what scanty description you give. Like a marine or truck electrical system. Or HVAC system...... A good source for me is a high voltage transformer from a dead microwave oven. It doesn't take a lot of electrical knowledge, just a lot of work and being careful. If it
must be regulated, just buy one, they're not
that expensive.
Using a hacksaw, remove the high voltage winding but leave the line volage winding. Use some sort of insulating layer to protect the wiring from the core. Milk jug plastic will work. Fische paper is the correct item but may be hard to come by. Cardstock from a shoe box will do if you can't find something better. The nice thing about the microwave transformer is that if you screw up and scratch or cut the wrong wires, just chunk it and start over.
Take a piece of AWG 14 or AWG 12 and take a half dozen wraps on the core. The exact number will vary a turn or two. Read AC volts and shoot for 21 volts(+/-) or so. DC voltage will actually be somewhat higher. Now, that gets into electrical theory and does get complicated. Just shoot for a couple of volts AC less that what the desired DC is.
The "
electric brick" you need is a bridge rectifier. They are available for 30 to 40 amps at 300 volts for a couple of bux. Some Chinese suppliers for less. Some US suppliers for more. Under $10 though, anywhere. About 1-1/4 inches square, 5/16" or so, thick. With four 1/4" stabs sticking up, and usually with a 5mm or 3/16" hole in the middle. A heat sink isn't necessary at your ampere rating, just a way to mount the brick. The metal is not
hot.
I highly recommend you use the quick disconnects that fit. They're cheap enough... ... Look for the two connectors that have the symbol (~) on opposite corners. Connect those to the transformer. The other two, (+) and (-) are the DC lines. Sometimes there is only a corner notched or a paint splotch to indicate the (+) line.The diagonal opposite is the (-) and the two others are the AC, the two (~).
Fuse the
line side about 5 amps, every one I've ever dealt with was 6 amps or better. So with 5 amps, you're safe. Rig a line cord, switch, and some sort of enclosure and you have an
unregulated 24 volt supply.
Bill Hudson