On 3/2/2017 7:00 PM, James wrote:
On 03/03/17 10:58, Frank Krygowski wrote:

One technical question for the electrical engineers: It's my
understanding that low-end multimeters read AC assuming a true sine wave
output. But I've encountered some dynamos have a different waveform.
Back when I had easy access to an oscilloscope and a true RMS meter, I
used that (expensive) true RMS meter to measure dynamo output. Do the
EEs think a simple multimeter is good enough in this situation?


I would replace the LED headlight with a 12 ohm resistor or 3W globe.
Then you have very close to a sine wave and unity power factor.

Back in the olden days, true rms meters and oscilloscopes were
expensive. Now you can get a true rms meter for under $40 and a
sufficient scope for low frequency (100Mhz) for under $30. Substituting
a resistor or incandescent bulb for the LED headlight light may not tell
you much that is useful.