Single pole voltage probe - uses solar cells to supply indicator circuits and has resistor, diode and capacitor

摘要

The single pole voltage probe uses the human body to complete the circuit. When the electrode (2) is touched the capacitor (5) is charged through the probe (1) and the diode (4) until the voltage dependent switch (6) conducts. The LED (8) lights up indicating the presence of a voltage. A rotor cell (7) supplies the circuit voltage and a second LED (10) indicates if the solar cell voltage is too low. A voltmeter supplied by an operational amplifier can be connected across the capacitor (5) to give a voltage reading.