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DiscoverCircuits.com -- Hobby Corner
Last Updated on:
Tuesday, June 01, 2021 03:06 PM
Hobby Circuits List
The contents &
graphics of Discovercircuits.com are copyright protected.
LINK to Dave's circuit, but DO NOT COPY any files to your WEB
SITE server |
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More
Automotive Circuits;
Switches |
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Car Ignition 12v Switch |
| A Discover
visitor needed a way to redirect +12v DC in his car to some auxiliary loads whenever
the car’s engine was running. Many cars have cigarette lighter outlet jacks,
which are either live all the time or become live when the car’s engine is running. |
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The visitor wanted to plug a device into a full time live
outlet but only switch on when the car’s engine was running. The circuit below performs
this function. It relies on the fact that the car’s battery voltage increases from
about 12.5v in standby mode to 14 volts whenever the engine is running. When the
voltage is above 13.5v, the circuit switches on a p-channel MOSFET. The circuit
uses a common LM393 dual voltage comparator and a 10v 5% zener diode as a voltage
reference.
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Click on Circuit Below to view PDF of Schematic |
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