Patent GB-1059851-A (GB)
Title: Periodically regenerative circuits
IPC: H03K3/2893
Filed: 1964-02-14
Abstract: 1,059,851. Transistor regenerative circuits. CARTER PRODUCTS Inc. Feb. 14, 1964 [Feb. 15, 1963], No. 6385/64. Heading H3T. A regenerative switching circuit having two distinct output states, one of which it assumes for all inputs above a given predetermined level and the other of which it assumes for all inputs below the same predetermined level comprises two reciprocally-coupled transistors forming a bi-stable pair and means for periodically interrupting the reciprocal coupling or otherwise rendering it ineffective whereby during said periods of interruption the circuit takes up a condition which is dependent solely upon the instantaneous value of input from which upon restoration of the coupling it goes to one or other of its triggered states independently of the previous triggered state occupied by the circuit. The circuit thus functions equivalently to a bi-stable trigger circuit but without the hysteresis or backlash effects normally observed in such circuits. Fig. 1 shows a Schmitt trigger circuit in which a transistor Q 2  connected in series in the cross-coupling from transistor Q 1  to transistor Q 3  is rendered periodically conducting and non-conducting by an alternating waveform applied to the primary winding of a transformer T 1 . In a modified form of circuit, Fig. 2 (not shown), transistor Q 2  is replaced by a switched transistor connected between the feedback path and earth so as to impose a periodic shunt thereon. In a further circuit, Fig. 3, transistors Q 31 , Q 32  constitute a reciprocally coupled pair of opposite-conductivity type transistors reciprocally coupled with a further transistor Q 30 , a balanced input being-applied to the bases of the transistors Q 30  and Q 32 . The common-emitter coupling for these two latter transistors is provided by a Zener-diode-stabilized constantcurrent transistor. A diode in the collector circuit of one of the transistors provides temperature compensation. Fig. 4 (not shown) illustrates a symmetrical circuit with cross-coupling from each transistor to the other as in an Eccles- Jordan circuit, the input being a balanced input applied between the bases of the two transistors and the interrupting means being connected between their collectors. In the circuits of Figs. 5-7 the feedback is periodically rendered ineffective by reducing the collector-emitter supply voltage for the circuit to a very low value. Fig. 5 (not shown) shows a symmetrically cross-coupled circuit having a balanced input applied between the bases. The supply voltage is normally too low to render the circuit effective, but a square-wave voltage is however superimposed on the collector supply line and during its positive-going portions the supply voltage for the transistor becomes sufficient to permit normal operation thereof. Figs. 6 and 7 (not shown) illustrate a Schmitt trigger circuit supplied from an unsmoothed full-wave rectifier circuit. A relay winding is arranged in the collector circuit of the output transistor and diodes are connected in parallel with the common-emitter resistor to increase conduction during the " on " periods of the output transistor. Fig. 7 (not shown) illustrates a circuit similar to that described in Specification 1,059,852.