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125KHz
Wireless Smart Key Detector
This circuit will turn on an indicator light whenever it detects a smart car
key containing an RFID chip. (added 7/06)
Automotive 12v Electrical System Voltage Indicator
This battery powered unit is designed to quickly aid troubleshooting of 12v
electrical systems in a car. Three LEDs proved a visual indication of a
+12v, ground or an open circuit voltage level.
Check Engine
Beeper
When wired into a car’s indicator light panel, this circuit will turn on a loud beeper
when the “check engine” light turns on. (added 7/06)
Fake Car Alarm Light
Whenever the car’s ignition is turned off, this circuit activates a flashing LED, which
can be positioned to appear as an active alarm system. (added 7/06)
Voltage Indicator
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...
