Discussion in 'Electronic Basics' started by Jack Hayes, Oct 20, 2004.

1. ### Jack HayesGuest

Is it possible/reasonable to build a peak reading voltmeter for 100 to 120
volt (RMS) near sine wave? The application is measuring peak voltage output
from engine driven generators that power battery chargers. Most of these
units cannot supply the current required at the top of the sine wave for
efficient battery charging, the result is reduced charging rate due to
flattening of the peak. I would like to be able to measure this.

Jack

2. ### John PopelishGuest

If you want to predict what the output from a rectifier will be
(without actually measuring that waveform or charging current) you
might replicate the rectifier with a smaller copy and load it with a
capacitor and a resistor (to slowly discharge the cap if the voltage
goes down). This gives a fair approximation of the peak voltage of

3. ### Terran MelconianGuest

Get a diode and a capacitor, and then measure it on your DC setting.
You'll need to select the diode and capacitor carefully, making sure
they're rated for at least the peak-to-peak voltage with some margin to
spare (say 20%); the most common random diodes and capacitors you might
have sitting around will be rated only for 50 or 100V, so you'll most
likely need to get some specifically.

A current-limiting resistor might also be a good idea for operator
safety.