On 17/08/2011 13:39, Electron wrote:
> But sometimes to offer a low impedance to a device under test may be usef=
ul,
> expecially if it's designed to run e.g. from a 12V Lead battery. One exam=
ple
> that comes to my mind right now is if the device uses the power rail to d=
ivert
> some energy (e.g. through diodes), a PSU that sources-sinks, or a battery=
,
> will absorb it, while a PSU that only sources will not and the voltage ma=
y
> raise dangerously.
>

Put a dummy load of resistance able to sink all the current the device=20
provided
Make PSU able to source that current + max current the device sinks

Output impedance is related to regulation of PSU, not the dummy load and=20
can be much lower than a 12V car battery (tiny fraction of ohm within=20
sink/source current limits) even if "dummy load" only needs to be 3 Ohms

A large enough capacitor will "sink" narrow enough spikes at any voltage.

--=20
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