Abstract: A sense circuit is provided connected to a control loop of a circuit having an output. The sense circuit receives a signal derived from the output of the circuit and provides a controlling signal to the control loop. In one embodiment, the sense circuit is connected to the output of a switching power supply and monitors the switched output to ensure that the main output of the power supply is kept within predetermined thresholds. The sense circuit includes first and second comparators comparing the switched output, in one embodiment, to a reference voltage, on one hand, and comparing the main output signal to the reference voltage, on the other hand.

Abstract: A traffic-control sign that automatically displays a primary message, such as "STOP", when electrical power is absent, and an optional secondary message, such as "We Arrest Drunk Drivers", when electrical power is present. The motorless sign is continually encompassed by an enclosure having a transparent facade. A plurality of pivotally-mounted louver panels arranged in a louvered fashion are viewable through the transparent facade. A linkage rod interconnecting the panels provides for unison rotation of the panels. The linkage rod communicates with a solenoid so that the panels assume two distinct positions dependent on the state of the solenoid. These distinct positions reveal primary and secondary viewing surfaces to which the respective messages are affixed. Panel travel approximating 180 degrees allows the messages to be displayed on the overall viewing surfaces formed by the combined individual panel surfaces.