Cheap, high amp dc power supply?

Is there any way to make a dc power supply capable of 50+ amps a

TI

Trevo

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I'd use the charger / battery setup, but otherwise I'd look for a good switcher design. "Silicon Chip" (Australia) may have published one.

Any linear system would be a brute - 600 W dropping maybe 150 W in the heatsinks? Nasty.

Consider designing what you want. A linear supply for 50 amps is usually too inefficient to be practical. (or you live in Antarctica and the waste heat will go to heating a room)

I have a couple of SCR controlled supplies that I like for high current and low heat. One (0-48 volts 5 amps) uses a two diode FWB and phase controlled SCR pass element, the other (0-24 volts 10 amps) uses a pair of SCR's that provide both rectification and control (downside is it takes a separate transformer winding to power the trigger circuit)

Neither of mine are "regulated" but as long as the line and load stay reasonably constant . . . I use them to control DC motors. Place I worked at awhile back used a similar scheme to control an electromagnet for a welding deflector - It has feedback and a differential amp to provide regulation.

With SCR's you just need to increase the size of the SCR for more current - the rest of the circuit pretty much stays the same. Easy to control 50 amps or more and make it continuously variable from

For sensitive loads you need good filtering - but if you're talking about 50 amps at 12 Volts you're probably not dealing with a sensitive load, at few amps 20,000 ufd would be plenty.

A lot of good, free, power supply design info is at:

I picked up a surplus 1,200 VA toroidal isolation transformer - it would make a nice power supply, The beauty of a toroid (in that size range especially) is it only takes two turns of wire (2.4T/V on mine) for every volt of output - right now it is working as a spot welder.

Hmm. Could you use the old standby of " car battery and trickle charger from Canadian Tire [or local equivalent]"? Do you need 50 amps for hours at a time or just intermittently? How precisely must it be 13.8 volts? Gotta define the problem before you can get a solution.

Bill

The price you mentioned is very good for the specs. Your only other alternative is to search out for one on eBay, or somewhere else. If you buy one used, be prepared to most likely have to service it.

Another cheap solution for 12 Volts at a high current rating is to get a car battery, and a charger. A car battery will give you hundreds of amperes. The greater the amp hour rating of the battery, the more time you can have between charges. The best type of lead acid battery for heavy discharge applications is one rated for deep discharge.