One of the inductive electric test pen circuits

Inductive electric test pens and alarms can respond to alarms at a certain distance from live objects. Carrying them with you can prevent
accidents caused by accidentally entering high-voltage areas or accidentally touching live objects. The sensitivity
of the inductive electric     test pen or alarm , that is, the reaction distance to the charged object, is generally required: 5 to 10m at 110 to 220kV, 2 to 5m at 35kV, 0.8 to 2.Sm at 10kV, and 0.8 to 2.Sm at 6kV. 0.5～1. 5m, 5-20cm when using 220V mains power. After users gain some practice, they can roughly estimate the voltage level based on the alarm distance. The circuit is shown in Figure 13-101. The applicable range is 50~35kV.     The sensitivity of the electroscope is related to the small copper piece at the G terminal (sometimes it may not be used) and the adjusting potentiometer RP.