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DiscoverCircuits.com -- Hobby Corner
Last Updated on:
Tuesday, June 01, 2021 03:06 PM
Hobby Circuits List
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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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