GB755064A - Circuit arrangement for coupling pulse sources to variable loads - Google Patents

Abstract

755,064. Pulse circuits. STANDARD TELEPHONES & CABLES, Ltd. July 16, 1954 [July 21, 1953], No. 20750/54. Class 40 (6). A circuit in which a pulse source is connected via an output transformer to a load the other side of which is connected to a variable potential, comprises means for preventing current flow through the transformer in the interval between pulses from the source, Fig. 1 shows a coincidence-gate circuit of the type described in Specification 682,985, [Group XXXIX], in which positive pulses from an input source es are passed to output O1 only wnen positive control pulses from sources, such as G, are applied via output transformers, such as T1, to all of the inputs m1 n1 p1 simultaneously. In the interval between pulses from source G a pulse from source es will cause a current flow through the secondary of transformer T1 and thence through other output transformers ; thus the load seen from T varies between pulses and the inter-pulse current flow may cause saturation of the transformer. Fig. 2 shows a circuit in which this current flow is prevented by means of a clamping rectifier G1, a shunt resistor R1 and possibly a decoupling rectifier G2. The variable load impedance at input m1 is represented by the variable impedance and source Zx and ex respectively, cs being the effective pulse source acting on the secondary winding of the transformer. Point m1 is also connected via a resistor R1 to fixed source E1 and to a clamping rectifier G1 which has its anode connected to a fixed source E2. It is shown by analysis that resistor R1 and voltage sources E1 and E2 can be given appropriate valves such that no current flows through Zp in the inter-pulse period and that the output impedance for transformer T1, Fig. 1, is constant during pulses. If the pulse from sources G and es are of negative polarity rectifiers G1 and G2 are reversed. Rectifier G2 is only essential when a number of pulse sources are connected in parallel it then provides the necessary decoupling between the sources.