AMPLITUDE STABILIZED TRANSISTOR DRIVE CIRCUIT FOR MECHANICAL OSCILLATORY SYSTEM

1,240,070. Electric timepieces. KIENZLE UHRENFABRIKEN G.m.b.H. Oct. 6, 1969 [Oct. 5, 1968], No. 49062/69. Heading G3T. An electric timepiece includes an electronic circuit for maintaining the oscillation of a mechanical oscillator and stabilizing the amplitude of oscillation thereof, and comprises a drive coil 3 and a control coil 4 connected, respectively, in the emitter-collector and base-emitter circuits of a driving transistor 1, to the base of which is connected the output terminal of a voltage divider in a branch of which is the emitter-collector circuit of a second transistor 2 having the control coil 4 connected in its base-emitter circuit. The voltage divider comprises resistors 5, 6, 7, the control coil 4, and the emitter-collector circuit of the transistor 2. In a modified circuit the resistor 7 is replaced by a resistor connecting the junction of the resistor 6 and the coil 4 with the base of the transistor 2. In other modified circuits a capacitor is connected to the base of the transistor 2 to provide self-starting of the oscillating system.