High current regulated power supply
I recently stipped a 200 amp transformer out of a battery charger. It is 20 volts 150 amps rms center tapped. I wanted to build a regulated high current power supply. Using an lm338 and possibly TIP41c 6 amp npn transistor as pass transistors, but i was wondering if i can do that? Do i need high power resistors or any other components? Could someone give me an easy to read or simple scheumatic/diagram please?
Look up the regulator, and check the data sheets from the manufacturer. Also places that make them, like National Semiconductor, Texas Instrument, Motorola (now known as On Semiconductor) should have application notes on how to use their products. A common circuit is the current increase circuit like you propose to extend the curent range of the regulator itself..
Obviously you are not proposing to make a 200 amp power supply, so this behemoth will need to be fused or otherwise limited because it can easily catch the whole thing on fire if a fault occurs.
Look into Foldback current limiting. This works best for high current regulators. Also you will need high power diodes with semi-fast recovery. You really shouldn't use a bridge pack when experimenting. There not as forgiving. Also if you are trying to do a variable voltage that will change alot. Start with fixed 12 volt and Foldback c.l. You will get there.
Btw. Resistors of that power wouldn't really be of use. You will however need low e.s.r capacitors to filter and stiffen the supply. I would suggest about 1/2 farad to 1 farad worth if using for a pulsing type of load. I.e car audio, ham radio. If not then use about 300,000mf or so. Computer grade electrolytics.
Starter parts list would be:
120 amp breaker or so.
4 gauge cable.
Capacitors of your choosing.
Your choice of regulator circuit.
Heatsinks of proper Caliber.
Potentiometer for current limit.
Fast recovery 100 amp diodes are greater.
Case for project.
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