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A while back, someone requested a
simple method to indicate when 20 to 50 amps of DC current was flowing through a wire.
The circuit below works well and is about as simple as you can get. A sensitive reed
relay from
www.Jameco.com acts as the current sensor. The magnetic field produced by such a
current is enough to close the relay contacts, if one or two turns are wound around the
relay. The turns do not have to be tight. I was able to close the contacts with two
turns about 2 inches in diameter with 20 amps. A simple LED and resistor can be used to
indicate the current by tapping into the automotive +12v supply. |
