Making series Vreg to sink current

[KasperM]

I just signed up after visiting this forum daily for some time - great forum!

I've been reading the "Regulators for high performance audio" articles in Audio Amateur by Walt Jung (and others).

Since the proposed voltage regulators are series type regulators they can not sink current. However WJ mentions a modification to series type regulators enabling them to both source and sink currents (bleed current). How is this done?


Kasper

 

[Nelson Pass]

One way is to load the regulator with a given
amount of resistance and by regulating the
voltage across the resistor, the device will
draw a relatively constant current.

For example, with a three pin positive regulator,
one pin goes to ground (or perhaps a negative rail),
a resistor goes from the output of the regulator to
this same ground, and the positive input pin of the
regulator will try to draw approximately the voltage
rating of the regulator output divided by the
resistor value. There will also be a small current
which runs the regulator itself, but this will also
tend to be constant.