GB1034793A - Improvements in and relating to crystal-controlled transistor oscillators - Google Patents

Abstract

1,034,793. Transistor oscillating circuits. BRITISH BROADCASTING CORPORATION. Aug. 6, 1963 [Aug. 14, 1962], No. 31183/62. Heading H3T. A transistor oscillator comprises a transistor amplifier 11 having its output circuit coupled to its input circuit through a phase shift network 10 suitable to permit self-oscillation, the emitter circuit of the transistor having a negative feedback circuit connected therein comprising two parallel connected branches, one containing a resistor 16 and the other a piezoelectric crystal 17, the resistor having a value such that in the absence of the crystal the negative feedback is sufficient to prevent oscillation, and the crystal serving at a predetermined frequency to reduce the effective resistance of the feedback circuit sufficiently to cause oscillation at this frequency to take place. In the circuit of Fig. 2 (not shown), a variable or fixed blocking capacitor is connected in series with the crystal 17 across the resistor 16 and in the circuit of Fig. 3 (not shown), battery 14 and resistor 13 of Fig. 1 are replaced by a Zener diode which serves to stabilize the base-emitter bias potential. Figs. 4-6 (not shown) are circuit diagrams of oscillators with the amplifier in common emitter, common base, or common collector configurations in which various phase shift networks using inductors, capacitors and resistors are disclosed.