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Circuits designed by David Johnson, P.E.
Last Updated on:
Monday, December 25, 2017 02:08 PM
List of Dave's Circuit Designs
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More
Driver Circuits,
Relay Circuits |
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Remote Relay Driver
April 2, 2014 |
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I received a call from a Discover Circuits
visitor who wanted a simple way to turn on an outside lighting
system using a low voltage control line. I suggested the simple
circuit below.
The circuit is
powered by a 9v battery and uses a very efficient latching
relay. Two low voltage wires lead from the a toggle switch to
the remote relay. A toggle switch selects either the on or off
condition of the relay. The relay contacts are rated at 10
amps, so the small relay can handle a sizeable amount of power. |
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The relay is a latching type with a single coil. The
switch either charges or discharges a 330uF capacitor through the
relay coil, latching or unlatching the relay state. With a quality
capacitor, the leakage current through the capacitor will only be a
few microamps. A 9v battery should therefore last for many years of
service. |
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Latching Relay |
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Click
on Drawing Below to view PDF version of Schematic |
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