GB1386693A - Transistor circuit for an oscillator - Google Patents

Abstract

1386693 Transistor lamp flasher STANDARD TELEPHONES & CABLES Ltd 13 April 1972 17064/72 Heading G4F [Also in Division H3] In a three-terminal transistor circuit for flashing a light L and including a first transistor element T5, T6, Fig. 3a, of one conductivity type, a second transistor element T7, T8 of the opposite conductivity type and a third transistor element T3, T4 of the one conductivity type, the first and third transistor elements T5, T6; T3, T4 comprise separate pairs of transistors of the one conductivity type, the emitters of each pair are directly connected together to constitute the emitter of the element, the collector of one transistor of a pair constitutes the collector of the element and the bases of the transistors of a pair are directly connected together and directly connected to the collector of the other transistor of the pair to constitute the base of the element. The collector of the second transistor element T7, T8 is connected to the emitter of the third transistor element T3, T4 and to one terminal 2, the collector of the third transistor element T3, T4 is connected to the emitter of the first transistor element T5, T6 and to a second terminal 1 which is connectable to a capacitor C thereby to produce an oscillator circuit, the collector of the first transistor element T5, T6 is connected to the base of the second transistor element T7, T8, a first resistive impedance R1 is connected between the bases of the first and third transistor elements and a second resistive impedance R2 is connected between the base of the first transistor element T5, T6 and the emitter of the second transistor element T7, T8 to which a third terminal 3 is connected. In an equivalent circuit, Fig. 3b, of the lamp flashes circuit shown in Fig. 3a when the capacitor C has charged sufficiently the transistor T10 turns on. This turns on the transistor T11 which lights the lamp L and turns the transistor T9 off. The capacitor C now discharges via T10 until the charge on the capacitor falls below a certain level which causes T10 to turn off. This turns off T11 and the lamp L and turns on T9 so that the capacitor C now recharges and the above cycle is repeated. The transistor circuit can be formed as an integrated circuit for connection to the capacitor C and lamp L.