High voltage detector
Simple high voltage detector based on JFET.
Used JFET: KP103I made in USSR:
Transistor can be tested with multimeter - its channel
resistance is ~700 ohm and it increases to few kOhms and more in electric
field (eg. near the mains cord).
Schematic:
Due to simplicity detector can be soldered directly on 6F22 battery socket:
