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Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
I don't think anything in the range of a few uC can trash these meters no matter what the voltage. What I have done in some is pull the 1/2 amp fuse out and stick a 22 ohm resistor in its place, so they can drive it up past the 4000 count level and the thing will just say OL.
Here's photos of another little analog meter I use ($7.). In the latest version they have added 5 VDRs that the previous ones didn't have! How they do that for that price is a mystery.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
radiotech wrote ...
I don't think anything in the range of a few uC can trash these meters no matter
well thats a good point, so long as the columb charge is smal lenough to bleed off and drop its voltage, faster than the damage can be done, ending in a lower voltage.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
never played with VDG so just as a thought; at a guess the VDG has a very high effective source impedance so the output current measured will depend upon the output voltage (plus the usual VDG stuff .. belt material, speed, humidity,cleanliness etc) so why not measure short-circuit output current (connect the meter between topload and ground BEFORE running the VDG) (and definitely DO NOT change ranges with the VDG running) This should allow easy and repeatable measurement of improvements as all parts of the meter and the topload will be at or near ground potential.
Putting a string of high voltage resistors between the topload and the dmm, still using current ranges, would allow an estimation of the eht voltage at light loads.
Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
In these current measurements make it sure that both leads of the meter are firmly connected, as sparks may damage the meter. It's possible to measure current by grounding one lead and connecting a sharp point to the other. Just approximating the point to the VDG terminal will draw all the current that is entering it without sparks.
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