Electric remote control transmitter

摘要

An electronic remote control transmitter employs a two transistor cascade oscillator having positive and negative feedback loops. The oscillator voltage is supplied through a switch assembly containing a plurality of momentary contact switches to a pair of voltage dividers supplying signal voltages in predetermined ratios to a two branch circuit in the negative feedback loop. One branch contains an inductor and the second branch a capacitor. Closure of any switch completes the DC circuits for the transistors. Signal voltage is supplied to the branches to produce a minimum amplitude, zero phase shift condition which establishes oscillation at that predetermined frequency. The output of the oscillator is amplified by a third transistor and supplied to an ultrasonic transducer for generating acoustical control signals.