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AC Current Controls Hour Meter
-- February 13, 2010
Many systems require
routine maintenance based on machine operation time. The circuit below is a
simple way to turn on a hour meter whenever AC power is supplied to the machine.
An inexpensive snap-on current transformer from Magnetics Inc, is used to detect
the AC current.
The
output of the transformer is fed to a voltage doubler circuit. When 0.5 AC amps
or more of current is flowing, the circuit generates sufficient voltage to turn on the
n-channel MOSFET. Once tuned on, the transistor routes voltage to the hour
meter. Some hour meters contain their own battery, so no external power is
needed.
In those cases, the transistor switch alone will turn
on the hour meter.
Magnetics Inc CR3110-3000
Current Transformer
Hour
Meter
Hour
Meter
Click on Drawing Below to view PDF version of Schematic
