Date: Mon,May 2 2005 8:01
From: "Glenn Ashmore"

The power to run the meter has to be isolated from the circuit being measured.
They need either a battery or an isolated dc/dc converter to power them.

After some search it looks like the typical 200mV digital meter modules
take about 1 to 2 mA.
Even if I use a couple of them, for voltage and some currents (to
trolling motor, other loads), I need max. about 10 mA. For this low
current, a transformer to isolate the DC seems to be overkill.

I am considering to take a simple 555 and insert a capacitor not only
in the output signal line, but also the return (no common 0V anymore)
line. On the "secondary" side would be a simple bridge rectifier, a 9V
Zener diode, and a capacitor to smooth the ripples.

Did anybody try something like that already? Other simple solutions?

TIA,

Stefan