Start:stop oscillator for colour TV carrier bursts - uses ultrasonic delay line with gain controlled feedback amplifier

摘要

The start stop oscillator generates colour carrier bursts etc. of constant frequency. The input and output of an ultrasonic delay line (1) are connected together via an amplifier (2) whose gain is large enough to cause the circuit to oscillate (7) at the passband frequency of the delay line. - The gain is controlled by a voltage (U2). This voltage is obtained from the resulting oscillations and is rectified (3). The rectifier output is coupled to an RC circuit (5, 6). The gain is reduced as the control voltage increases in the presence of the oscillations.