how do I isolate DVOM probes from the power source - Electronic Circuits Projects Diagrams Free

tesla2008 · 4th November 2009, 06:42 AM

I have this DVOM:

http://www.rpelectronics.com/Default...s/PM-1029A.asp

DVOM uses 9V for power display and electronics

A 24v battery and a linear voltage regulator (set at 9V) feeds the circuitry of DVOM. I can measure any DC voltage within its preset range (0 to 200V) as long as that is part of separate circuit, say a battery, another power supply etc.

but when I try to measure the voltage on same battery pack that feeds the voltage regulator the DVOM digits disappear and only couple of segments are displayed in first digit.
removing the ground DVOM probe from the circuit restores the digits to "0000".

apparently negative/ground for 9V DVOM and negative/ground probe do not play well.

so, how do i isolate those two negatives from each other so that I can measure the power from same battery pack that feeds the DVOM via voltage regulator?

MikeMl · 4th November 2009, 07:03 AM

Buy a dPm that includes the isolated power supply. Or build a switcher with an isolated winding on the inductor

tesla2008 · 4th November 2009, 05:03 PM

Quote:

Originally Posted by MikeMl

Buy a dPm that includes the isolated power supply. Or build a switcher with an isolated winding on the inductor

I see
that seem to be par of the design that you cannot use the common ground
thanks for the information

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4th November 2009, 06:42 AM	#1
tesla2008	how do I isolate DVOM probes from the power source I have this DVOM: http://www.rpelectronics.com/Default...s/PM-1029A.asp DVOM uses 9V for power display and electronics A 24v battery and a linear voltage regulator (set at 9V) feeds the circuitry of DVOM. I can measure any DC voltage within its preset range (0 to 200V) as long as that is part of separate circuit, say a battery, another power supply etc. but when I try to measure the voltage on same battery pack that feeds the voltage regulator the DVOM digits disappear and only couple of segments are displayed in first digit. removing the ground DVOM probe from the circuit restores the digits to "0000". apparently negative/ground for 9V DVOM and negative/ground probe do not play well. so, how do i isolate those two negatives from each other so that I can measure the power from same battery pack that feeds the DVOM via voltage regulator? Last edited by tesla2008; 4th November 2009 at 06:46 AM.

4th November 2009, 07:03 AM	#2
MikeMl	Buy a dPm that includes the isolated power supply. Or build a switcher with an isolated winding on the inductor __________________ Mike ML.