Temporary voltage dependent blocking cct. - triggers current branch on max. operating voltage, while reblocking on values below max.

摘要

The circuit is intended for temporary current blocking, dependent on the operating voltage value. The current is switched through on a maximum value being reached, and blocked again when this value drops below this maximum. Thus it protects the sensor circuit in a triac phase control circuit from high switch-on noise. A transistor switch is coupled to the sensor and to the input by its collector, and its base is connected to a second transistor switch and a constant current source. A second current source is coupled over a zener diode and a voltage divider to the second transistor base. The zener diode is shunted by two transistors together acting as a thyristor.