what about the wimhurst generator?

[Pirate88179]

@ TinselKoala:

I agree with your assessment of the ammeter side of the dmm. In the early days of my earth battery experiments, I was only getting about12-15 mA's out of it so, I made a few changes and then made some tests.  Well, I set my meter on the same 20 mA setting and .....poof!  I was no longer getting any readings on this part of my meter.  I first just figured I screwed up my earth battery somehow.  Later, when using it to test something else, I noticed I was still not getting anything out of the amps side.  So, I opened up the meter and one of the 2 fuses inside was blown.  It took me a few days of driving around town to find that fuse. (I bought several of them)  Suddenly, the meter was working again as it should.

Then I checked my earth battery again using a higher setting and, duh, I was now reading about 30 mA's.  For a while there, I had "assumed" I had purchased a bad meter and chalked it up to bad luck on my part.  Now, I set everything on the meter much higher than I think I will ever get and have only blown 1 fuse since.

I have used meters for years but always on known quantities.  When working on new stuff like this, I have found it is better to err on the side of caution.

Anyway, for what it is worth, I think your advice was good.

Bill

[Steven Dufresne]

To measure current and voltage at the same time I used to put both the ammeter and the voltmeter inline with the circuit. I later realized that the high resistance of the voltmeter kills the current, so the ammeter would always read low. Now I put the ammeter and a small resistor inline with the circuit and put the voltmeter in parallel with the small resistor. Now most of the current goes through the small resistor unimpeded so the ammeter reads okay. I wonder how many experiments would have turned out different had I known better at the time.
-Steve
http://rimstar.org   wsminfo.org