12V Vehicle Electrical Wiring Tester Circuit

12V Vehicle Electrical Wiring Tester

12V Vehicle Electrical Wiring Tester Circuit

This little tester is useful for checking vehicle electrical circuits. Two LEDs indicate whether one of the clips is connected to the positive supply line (red) or to ground (green).

R1 150Ω
R2 150Ω
D1 Green LED
D2 Red LED
D3 6.8V 1/4W Zener Diode
D5 6.8V 1/4W Zener Diode

The unit is powered by the vehicle battery. It is advisable to terminate the unit into  two insulated heavy-duty crocodile clips. These enable connection to be made directly to the battery or to terminals on the fuse box. It is also possible to terminate it into a suitable connector that fits into the cigarette lighter socket.

IF a sharp needle is soldered to test point, it is possible to check insulated wiring, but only those that carry 12V. Although the needle pierces the insulation, it does not damage it.

12V Vehicle Electrical Wiring Tester 12V Car Electrical Wiring Tester

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