Abstract: A control circuit for a power switch like a triac to be connected in series with a load device, at a situs where only one AC power conductor and a conductor extending to the load device is available, is energized from a DC power supply energized from these conductors. The power supply includes at least one rectifier connected in series with a capacitor, the terminals of which capacitor constitute the DC output terminal of the DC power supply, an impedance of much greater resistance than that of the load device and through which the capacitor is charged when the triac is in its non-conductive mode, and a normally non-conductive triggerable low impedance threshold device shunting the high impedance and triggered momentarily into conduction as the applied AC voltage goes through zero when the triac is to be in its conductive mode. Current flow through this threshold device triggers the power switch into conduction a short interval after passage of this voltage through zero.

Abstract: A combination control knob and encoder drum unit, which has a number of indexing indentations corresponding to the number of desired stable positions thereof, is sized to pass through an opening in a control panel behind which is mounted a drum-receiving housing. The drum has groups of light-transparent areas each for providing a pattern of light identifying a different signal channel. The housing has a light source which passes within the drum when it is fully mounted within the housing, and a bearing adapted to receive a shaft extending from the combination knob and encoder unit. A spring loaded drum holding projection is urged toward and enters an adjacent encoder unit indentation. The housing has photocell means at a light pattern reading station to which the various groups of light-transmitting areas on the drum can be individually brought.

Abstract: The emission of the various electron guns of a color cathode ray tube are measured and indicated by a time sharing multiplexing technique where emission generating voltages are fed to the electrodes of the various electron guns in rapidly repeated sequence and the degree of emission thereof is displayed simultaneously on the faces of current meters responsive to average current flow. Such a technique permits simultaneous display of emission current for in-line cathode ray tubes having commonly connected control and/or accelerator electrodes, where individually adjustable spot cut-off voltages are sequentially connected to the set of commonly connected electrodes involved in synchronism at any given instant with the connections of the cathode electrode thereto which is to be assigned to the adjustable voltage involved.