I am looking to build a dual polarity power supply for prototyping my projects. I am looking at
a variable output voltage of +/- 0 to 40V DC, max current drawn 5A DC. Does anyone know any circuits that can do this ? I was searching for RC4194 based designs and LM317 / LM337 based designs. Any suggestions ?
I am looking to build a dual polarity power supply for prototyping my projects. I am looking at
a variable output voltage of +/- 0 to 40V DC, max current drawn 5A DC. Does anyone know any circuits that can do this ? I was searching for RC4194 based designs and LM317 / LM337 based designs. Any suggestions ?
Another choice would be the LM350T. It's a drop-in replacement for the LM317, but does 3A instead of 1.5A. (And Eric may be right, 5A for the negative supply is likely much more than you would ever need.)
To get the LM350/LM337 to 0V, however, you have to muck with them a bit. Without adding some opposite polarity biasing in the adjustment legs, they both start out at about 1.2V. And you'd have to add some circuitry to make them track, if so desired. There may be some good single-chip tracking regulators out there, but none are coming to mind.
EDIT: I forgot the LM338K: another replacement for the LM317, but does 5A.
Ericgibbs, a number of the circuits that I want to prototype ( most of them are audio power amps, though not all) require supplies dual polarity supplies +/- 35Vdc at 2A. I gave upper limit of 5A. They are all discrete transistor based designs from Phillips design audio amplifier design book. Do you forsee any problems with the power supply ?
Ericgibbs, a number of the circuits that I want to prototype ( most of them are audio power amps, though not all) require supplies dual polarity supplies +/- 35Vdc at 2A. I gave upper limit of 5A. They are all discrete transistor based designs from Phillips design audio amplifier design book. Do you forsee any problems with the power supply ?
Probably your most difficult requirement is the 0V minimum. Your monolithic regulators tend to have a reference around 1.2V. And, at 5A, at any low voltage, the pass elements must dissipate 5A*(Vunreg - Vout).
A much easier design would be +/-20 to 40V @ 5A. (With option for voltages below 20V at reduced current.)
From a practical sense, do you really need a regulated supply? You may find that a +/-40V unregulated (simple bridge on a 56VCT transformer), supplied by a 500VA variac would suffice. It would be a lot cheaper.
This is a great point. But, it's still do-able if one really wants it. Many commercial power supplies use relays to switch to lower voltage secondary taps...