ELECTROSTATIC_DETECTOR

Published:2009/7/7 23:09:00 Author:May | From:SeekIC

The heart of the electroscope is the two junction FETs Q1 and Q2 connected in a balanced-bridge circuit. The gate input of Q1 is connected to the wire pick-up antenna, while Q2's gate is tied to the circuit's common ground through R2. That type of bridge circuit offers excellent temperature stability; therefore, Q1 is allowed to operate in an open-gate configuration. Potentiometer R7 is used to balance the bridge circuit, and R6 sets the maximum meter swing. Capacitors C1 and C2 help to reduce the 60-Hz pickup and add to the short-term stability of the circuit.



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