DC motor protective switching cct. - has regulating signal dependent on supply current controlling monostable or bistable flip-flop

摘要

The protective switching circuit, for d.c. motors, uses a signal proportional to the motor supply current to operate a protective cut-out system. The signal magnitude depends upon a current inversely proportional to the motor's operating voltage. The signal is applied as a base-emitter voltage to a flip-flop input transistor. The flip-flop may be either monostable or bistable. The signal is obtained from a resistor. The supply voltage is adjusted by a potentiometer whose tapping is connected to the resistor. The collector of the flip-flop output transistor is coupled over a diode to a control line.