To good to be true?

[gwolf]

Last year I have posted a shunt regulator design using positive feedback error correction:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=18871

But it needs more than 2 transistors ...

Cheers,

Gerhard

 

[destroyer X]

Hello Elso, also boholm and all others

I know this is not only 2 transistors..... each side at leat tree...but, as i am using 33 years long, and i construct more than a hundred to friends use their 20 Amperes consumption SSB Radio Transmitters (consumption moves from miliamperes to 20 amperes in a matter of some microseconds) that i decided to show you.

A lot off supplies is almost this one.... the difference is that one is tested a lot, long time testing... some users died and his son is melting strong wires only to joke.... only to see it melt making output short circuit.

Do not answer your question.... but i send it to say you hello... also boholm and other friends.

Carlos

Carlos

 

[john curl]

This last schematic is representative of what a '2 transistor' regulator would normally look like. This was the original design for dc regulators in the '50's and '60's. Many early transistor design textbooks have this model.

 

[johnnyx]

One of the transistors could be used as a zener, the reverse breakdown voltage of the base - emitter junction is about 6 to 7 volts. If the current is limited to a few mA, then it can be used as a zener substitute. (this is why the max voltage for TTL is specified as 6V, and why the max reverse VBE is 5V in most transistor data sheets.)
It's a noisy one though, I've seen it used as a white noise source, compared to a band - gap reference. Just like all zeners above about 5V, they are really "avalanche breakdowns", and this is a noisy process.