measure amp for home build generator

Thread Starter


Joined Jun 2, 2007
I have put a 1 by 1 by 3 cm piece of neodymium (N 45) on a wheel, wrapped some 140 rounds of coil around it. I can measure the resistance of the coil to be around 30 ohm. If I turn the wheel, it produces 70 millivolts averaged. But I cannot measure any amps. If I put my meter on a resolution of 200picoamp, it shows zero. Sometimes, it shows a minus sign, then that sign disappears.

Hmm, is the current generated much to low? how do I measure the output? do I have to put in a resistance? a load? is the ampmeter in itself not a load?

I dont get it. 30=0.07xAMP, right? so why am I not seeing 0.002333 amp?



Joined Apr 20, 2004
Your image shows a meter set to measure 200 ohms (not amps)full scale. This is not at all informative about the arrangement of your test rig.