GB753687A - Electronic circuit adapted to assume a number of stable conditions - Google Patents

Abstract

753,687. Multi-stable state circuits. EBAUCHES SOC. ANON. March 17, 1954 [June 4, 1953], No. 7718/54. Class 40 (6). A multi-stable state circuit comprises an odd number (greater than one) of electronic control devices, for example, discharge tubes or transistors which are connected in a closed ring or chain the potential of the control element of each device being determined by a potential divider having two arms connected to the anodes of adjacent devices and the third to a negative voltage source and in which the devices, with the exception of two adjacent ones, are alternately in the conducting and non-conducting condition, the state of conductivity being progressed along the devices by the application of pulses to the circuit. Fig. 1 shows a three stable-state counter or frequency divider circuit comprising ring-coupled tubes T1, T2, T3 in which normally T2 and T3 are conducting and T1 cut-off. When a first positive pulse is applied at V2, T1 conducts and T2 is thus cutoff, T3 remaining conducting, a second pulse on V2 causes T3 to cut-off and T1 and T2 conduct and a third pulse causes T1 to be cut-off and T2, T3 to conduct. The tendency for T3 to be cut-off when T2 is rendered conductive is offset by the positive pulse applied to its grid from T1 via capacitor C. The absence of a capacitive coupling between the anode of T3 and grid of T1 ensures the stability of the circuit. In a modification, Fig. 2 (not shown), grid damping resistors maintain the stability of the circuit. In a further modification shown in Fig. 3 stability is obtained by the use of an auxiliary tube T4 associated with tube T3 of the chain, the D.C. coupling being between the anode of T3 and the grid of T1 and the A.C. coupling between the anode of tube T4 and the grid of T via a capacitor C. Fig. 4 shows a circuit having five stable states in which neutralizing capacitors C are provided which as described in connection with Fig. 1 prevent undesired changeover of the tubes. In a further modification, Fig. 5 (not shown), stability is obtained by omitting certain of the inter-stage coupling capacitors and providing grid stopper resistors. Damping resistors may be used in series with the inter-stage coupling capacitors, Fig. 6 (not shown).