[sdiy] generate 0v from out of nothing..

[Scott Bernardi]

If you're just tying opamp inputs (ie, reference voltages) to it, it
should work fine. If it has to handle ac currents (like the bottom end
of a resistor that has a signal at the top) then the transient response
of the opamp comes into play. If you pulse it with a changing current,
the 0v would have a small ac perturbation, which would be passed on to
your opamp inputs. Regulators do the same thing, except it takes much
larger currents to perturb the outputs.

Nils Pipenbrinck wrote:
> 
> This is somehow related to the pcb topic.. something just came into my mind:
> 
> Isn't there a old analog-guru trick to generate 0V from out of nothing? This
> would help me a lot because my biggest problem with the pcb is the
> ground-signal (which is used almost everywhere)-
> 
> I think about using a free opamp in my TL074. Just generate a voltage near
> 0V from V+ and V- with a voltage divider from the rails, and connect them
> with the positive and negative input of a opamp. In theory this should give
> me a nice 0V at the output, shouldn't it?
> 
> I've never did it.. maybe that thing begins to oscillate or so.. or it
> outputs anything but not 0V.. Is this practical? (I don't put a big load at
> the 0V. maybe 1 or 2 mA - just need it as a reference for other opamps).
> 
> Nils Pipenbrinck

-- 
Scott Bernardi
sbernardi at home.net