Battery Polarity Detection of GVDA GD110A AC Voltage Tester 12~300V, 50/60HZ Electrical Screwdriver LCD Display Voltage Detector Test Pen Electrician Tools
When the tester is on, press and hold the button while touching the test probe to the positive terminal, the other hand press and hold the negative terminal. if the polarity is correct, the screen display "--P" and the buzzer sounds. if it is reversely connected, the test pen doesn't respond.
