Abstract: A transient voltage surge suppressor and short circuit monitor unit in an alternating current transmission system includes a metallic case or casing into which lead lines connected to each of the power lines and to the neutral lines are introduced. The metallic case encompasses a series-connected varistor and fuse pair connected between each lead from an incoming alternating current power line and the lead from the neutral line. A series-connected neon lamp and limiting resistor pair inside of the case are connected across each varistor to be normally energized to give visual indication of the effectiveness and readiness of the suppressor to pass voltage surges above a predetermined maximum voltage to neutral, and to give visual indication that there is no short circuit between the power lines and the neutral line.

Abstract: A motor control circuit controls the speed of a single-phase split capacitor or shaded pole electric motor, and permits operation of the motor over a wide range of speeds without stalling. A first gated bilateral switch such as a triac is connected in series with the motor, and is fired by an integrating circuit through a second bilateral switch such as a diac. The integrating circuit charges through the start winding of the motor and a potentiometer which adjusts the rate of charging of the integrating circuit for the minimum speed setting desired. The motor control circuit also includes a temperature sensing bridge which becomes unbalanced as a function of increasing temperature. A light emitting diode connected to the bridge emits light as a function of the unbalance of the bridge.