Regardless of the shape of the test pen, its structural principle is basically the same. The outer shell is mostly a plastic insulator, and the inside is composed of a metal conductor, a small light bulb and a resistance wire. The small light bulb is filled with a colorless inert gas (neon gas), which can generate red light with strong transmission under the excitation of an electric field. When the object is charged, use an electric pen to test the neon bulb to turn red, otherwise the neon bulb will not light up.
AC Voltage Tester Pen GD116B :
Pls Clink Below Photo and Read more details about this AC Voltage Tester Pen GD116B :
