If it's less than an amp, I suggest just using a LM7812 and LM7912. Quick and easy, works great, thermal protection, one part and a couple of caps - done.
The thing is I only have a 20V transformer, diodes, 7812 and a bunch of transistors and other basic discrete components. I dont have 7912. I was hoping that its possible make a transistor circuit.
Yeah, you're going to need two windings. If it's center-tapped it might do it if the rectified, filtered voltage comes out over 12v each side - but even then you are probably going to need low-dropout regulators (the 7812 needs a 3v differential).
The transformer has a single winding and about the current rating im not too sure if there is a way of testing to find out since there is no inscription on it. I'll consider the 7912 option.
The transformer has a single winding and about the current rating im not too sure if there is a way of testing to find out since there is no inscription on it. I'll consider the 7912 option.
Unwind half the secondary, tap it off, and rewind, giving you the opportunity to use the 7912 option ;-). Or purchase another transformer, cheapskate ;-).
The transformer has a single winding and about the current rating im not too sure if there is a way of testing to find out since there is no inscription on it. I'll consider the 7912 option.
That will certainly work but if significantly more current is drawn from one rail than the other then the transformer's core might saturate and overheat.
It depends on what it's being used to power, if it's a general purpose bench-top PSU then I wouldn't recommend it but if it's being used to power an audio amplifier it's ideal as the current draw is roughly symmetrical.
It depends on what it's being used to power, if it's a general purpose bench-top PSU then I wouldn't recommend it but if it's being used to power an audio amplifier it's ideal as the current draw is roughly symmetrical.