| 摘要 |
631,884. Pulse circuits. WELLS, F. H. Dec. 6, 1946, No. '36111. Convention date, Feb. 1. [Class 40 (vi)] In a circuit designed to respond only to a critically spaced set of pulses, of the type in which the input pulses are applied both directly and through a delay line to a gate valve, actuation of the circuit by a false signal such as a single long pulse is avoided by first converting the input pulses to pulses of constant length. The incoming pulses are applied through an amplifier valve 17,. Fig. 1,.to a blocking oscillator valve 10 to produce a pulse of constant length in response to an input pulse. The output of valve 10 is fed directly and through a delay circuit comprising valve 30 and section T3 of line 26 to a gate valve 11 which conducts to produce an output pulse when two pulses spaced by the delay of the delay circuit occur. The delay circuit may be extended to T7 so that the circuit will respond to two different pulse spacings a second gating valve 58 being provided for this purpose. An alternative tap T6 on the delay circuit is provided for responding to an alternative second critical pulse spacing. A switch 59 is provided for biassing the gate valve 58 permanently beyond cut-off when it is not required. Resistance capacitance networks 28, 29 and 55, 56 are provided in the couplings between the delay circuits and the gate valves in conjunction with grid current in the gate valves to correct for distortion of pulses in the delay circuit, Fig. 2 (not shown). In a modification, Fig. 3, a circuit is shown for responding to three equally spaced pulses in which the coincidence of the second one with the first after delay in line 65 causes a gate valve 60 to open and trip regeneratively coupled valve 66, which sends a pulse down line 68, this pulse opening gate valve 61 to produce an output pulse if the gate valve has been prepared by the arrival of a second pulse from the valve 66, which is forthcoming only if the third pulse coincides with the second after delay in line 65 in gate valve 60. Specification 592,804 is referred to.
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