Abstract: A circuit status indicating device is used to monitor separate circuits to indicate their on/off status. Each circuit conducts an AC operating signal when switched to "on" status and an AC non-operating signal when switched to "off" status. The AC non-operating signal can be zero or some fraction of the AC operating signal, depending on the type of contact switches used in the circuit being monitored. A separate LED is provided for each circuit monitored. A separate AC input signal corresponding to one of the AC operating and non-operating signals in each monitored circuit is received and compared with a modified AC reference signal to produce an AC comparison output signal. A DC reference signal is compared with the AC comparison output signal and produces a DC output signal when the AC comparison output signal exceeds the DC reference signal.

Abstract: A motor control circuit utilizes sample and hold circuitry whose operation is initiated by an analog switch to control the firing angle of silicon control rectifiers, thereby to minimize wasting of power supplied to the motor being controlled.