Improvements in or relating to electric oscillation generators

690,013. Valve generating circuits. STANDARD TELEPHONES & CABLES, Ltd. July 17, 1951, No. 16932/51. Class 40 (vi). An oscillator of the bridge stabilized type comprises amplifying stages and coupling networks arranged alternately in a loop, one coupling network comprising a bridge network including a temperature dependent resistance, and another a parallel resonant circuit for determining the oscillation frequency. As shown, the bridge comprises the resistors 3, 4 5 and thermistor 6 and the other coupling network comprises a parallel resonant circuit 9, 10.. The anode of valve 1 is connected to a tap on the inductor and the grid of the valve 2 is connected to a capacitative potential divider to reduce the effect of changes of interelectrode capacitance on the frequency. The output may be derived from the cathode of valve 2 or from the potential divider (Fig. 2, not shown). One of the arms 3, 4 or 5 of the bridge may be in the form of a block of thermistor material in order to compensate for changes in ambient temperature. A capacitor 8 across arm 5 neutralizes the effect on the bridge of the output capacity of valve 2. Specification 510,379 is referred to.