GB1389257A - Pulse generators - Google Patents

Abstract

1389257 Pulse generator circuits BRITISH AIRCRAFT CORP Ltd 31 July 1973 [7 June 1972] 26571/72 Headings G4D D7X D6Y D6C1 and D6C2 [Also in Division G4] A pulse generator comprises a clockpulse source feeding an adjustable counter for determining the pulse repetition period and an adjustable counter for determining the pulse duration, electronic means being provided for inhibiting operation if the adjustment settings are inadmissible, e.g. if the pulse duration is set to be longer than the pulse period. The circuit described also provides delayed pulses. The clock 10 feeds a repetition period determining counter 12 which starts counting at a reset value selected by a control 26 and a "9's complement circuit" 28. When a circuit 42 detects a count of 998 it sets a bi-stable circuit 44 to provide an output at 50. The bi-stable circuit also opens a gate 14 to allow a similar adjustable counter 20 to operate and to reset the bi-stable circuit when full as so to terminate the output of 50. The detector 42 also sets a bi-stable circuit 52 which opens a gate 16 allowing the clockpulses to pass to a third adjustable counter 22 which, when full, sets a bi-stable circuit 56 to produce an output at 62. The bi-stable circuit opens a gate 18 allowing the clockpulses to pass to a fourth adjustable counter 24 which, when full, resets the bistable circuit and terminates the output at 62. Thus pulses are produced at 62 having the same repetition frequency of those at 50 but adjustably delayed with respect thereto by the count in 12. A counter 43 is full at one pulse less than counter 42 and controls a NAND gate 64 but if the pulse from the bi-stable circuit 44 has not ended before the end of the pulse repetition , period, the gate 48 is closed and the output at 50 is blocked. A similar circuit including a NAND gate 70 closes gate 60 to block the output at 62. A further detector 76 causes the output to be blocked if the pulse repetition period is too short.