Help with negative discrete regulator

[youyoung21147]

Hello,

I've read with much interest those pages about discrete Zener regulators.

The schematic I'm interested in is the second one on this page


My problem is that I don't know how to make it functionnal for the negative supply :

- should I use the unregulated negative rail like the ground, and the ground as the positive rail ?

- should I "mirror" the circuit and use PNP insted of NPN (and vice-versa) ?




Thanks in advance !

[AndrewT]

Hi, often negative regulators perform less well.
The link shows that both PNP and NPN active devices at work, so it may be that a negative version will work just as well.

Back to your question:- the negative can be an inverted positive by swapping around the polarity of the components.
or
Build two positive regs. Connect one +ve output to the ground of the other. Call this connection your 0v common. The other two outputs are your +ve & -ve supplies.

[youyoung21147]

Build two positive regs. Connect one +ve output to the ground of the other. Call this connection your 0v common. The other two outputs are your +ve & -ve supplies.

OK thanks ! I were not sure it was a good solution regarding to the ground impedance, so I wanted to be sure it was correct doing this.

Surely the simplest solution for me



Cheers