Abstract: An electrical power line transient noise filtering device is disclosed in the specification and drawings comprising a step up transformer connected to two continuous resistors. The high voltage winding of a step down transformer is connected to the other ends of the resistors. Low frequency power passes easily through the system but noise pulses are effectively blocked because they must pass through a transmission line of high loss.

Abstract: A device to control machines by voice is disclosed which responds to a plurality of predetermined musical tones in a sequence to generate a digital control output signal. Audio conversion means convert the sequence of tones into a corresponding sequence of digital number signals which are temporarily stored in a memory. Then a sequence of ratio signals are generated by dividing each of the digital number signals by one of the digital number signals. The resulting sequence of ratio signals is then converted into a corresponding sequence of digital numbers which comprises the digital control output signal. A microprocessor and associated storage processes the digital data and controls the conversion of the musical tones into corresponding digital numbers.

Abstract: A low-cost photoelectric machine access safety device is technically disclosed in the specification and drawings comprising an integral support structure supporting a retrodirective reflective (RDR) material facing an enclosed area which is to be guarded. A rotatable mirror causes a light beam from a reflex photohead to scan the guarded area. The RDR material reflects the light beam back along the transmitted path at varying angles of incidence. A photocell in the reflex photohead is activated to operate a control circuit to keep a control relay energized. Upon any interruption of the scanning light beam the relay is deenergized causing the accessed machine to stop. False operation preventing means prevents false operation when the light beam is scanning the portion of the support structure on which the rotatable mirror and associated apparatus is mounted. Fail-safe circuitry is also disclosed.