Voltage regulators

[bdl666]

I have an old Radio Shack power supply that was capable of producing 10 amps at 12 volts, but my brother took out the board and left me with the transformer and bridge rectifier. I was planning on making an inexpensive regulator for it using a couple of LM1084 regulators.

Now my question is. Can I use 3 of them in parallel to get the 10 amps and have some overhead so they won't run so hot?
I want it for testing car stereos.

 

[Harrkev]

The definite answer is --- possibly... It depends on how you wire them.

I have not used a 1084, but I have jused 7805s and other adjustables. The problem is that if they are not set to exactly the same voltage, then the one set to the lowest voltage will do all of the work. If it has a thermal cutoff, then it will die, and the next lowest one will take over. When it dies, the last one takes over. If you are lucky, the first one will have cooled off by this point. If not, bye-bye power.

The trick is getting all of the at EXACTLY the same voltage. If each has its own biasing resistors, you would need to put a small adjustable resistor in there and tweak the values until each of them puts out almost exactly the same current. IF they all use the same biasing network, then you have to deal with manufacturing variations in the internal zener diode, which you cannot compensate for.

If you have the parts and you have the time, try it and see. And if one regulator gets hot and the other two stay cool, then you know the problem.