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DiscoverCircuits.com -- Hobby Corner
"Hobby Circuits for
your Hobby Projects"
Last Updated on:
06/19/2009 02:53:51 PM
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Automotive 12v Electrical System
Voltage Indicator
designed by David Johnson, P.E. |
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Click on Schematic below to view PDF
version of this Circuit |
| When troubleshooting the
12v electrical system of an automobile, it is nice to have a simple voltage indicator
tool instead of a voltmeter. This electronic circuit, hobby circuit is powered by
two AA or even two N cells, which will provide enough energy for years of service.
The circuit has only two leads. One lead connects to the chassis ground of the
car. The second lead can be sharp tip probe. The circuit will indicate if an automotive
electrical circuit has zero volts or 12 volts present. If the voltage is near +12v, a
green LED will turn on. If the voltage is near chassis ground a red LED will turn
on. If the circuit is open, neither light will light. The circuit draws so little
current in the open standby mode that no on/off switch is required. |
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