Abstract: This adapter has a housing containing an automatic electrical switching circuit, a plug for connecting the circuit to an external A.C. power source, and sockets for mounting primary and standby lamps on the housing in circuit with the switching circuit. The circuit includes a conventional rectifier bridge and a transistor which is normally biased off so that the standby lamp is off, when the primary lamp lights. When the primary lamp goes off (burns out), the transistor conducts and the standby lamp is automatically turned on. When the primary lamp again operates the transistor is again biased off and the standby lamp is automatically turned off. A signal lamp in the switch circuit lights when the standby lamp is on. Motors or other power consuming devices may be substituted for the lamps.

Abstract: A heat sink housing for electronic components comprises a metal tube having four walls formed with internal and external ridges and grooves. The inside ridges and grooves removably support circuit boards and separate circuit members. The external ridges maximize radiation of heat from inside the tube. Two cover plates are removably attached to open ends of the tube to form a closed compartment in the tube.

Abstract: A small self-contained voltage monitoring device, which can be connected to a power line, has a display driver in circuit with a plurality of lamps to light one lamp at a time, depending on the power line voltage. A first oscillator in circuit with the display driver is actuated to operate a sound generator and alarm if the power line voltage falls outside a preset range. A second oscillator is in circuit with the first oscillator if the power line voltage is interrupted even momentarily, both oscillators are actuated by an auxiliary power source to generate a different sounding alarm. The alarm will continue to sound even if the power line voltage is restored until the auxiliary power source is manually deactivated.