is a simple device that serves to determine the polarity of the voltage of the wiring. Circuit tester is made with 4 pieces diodes, 2 LEDs and a resistor. Technically, the working principle of the tester utilizes a forward bias on the diode D4, D5, D6 and D7, then forwards it to the LED bias fordward D1 and D2. Circuit tester is quite simple and requires no external voltage source.
Circuit Voltage Polarity Tester
Parts List Voltage Polarity Tester
- D1, D2 = LED
- D3, D4, D5, D6 = 1N4001
- R1 = 1K
Technique Using Voltage Polarity Tester
- If LED D1 and LED D2 lights extinguished, then the line or cable at the probe 1 is positive and the line or cable to the probe 2 is negative.
- If LED D1 and LED D2 lights extinguished, then the line or cable at the probe 1 is negative and line or cable at the probe 2 is positive.
- And If both LEDs D1 and D2 is on the path that the test is an AC line
- is only safe to use for the object under test in 12volt. If you want to use this tester for a test object with a voltage above 12 volts the value of R1 should be replaced with a larger value.