GB640358A - Improvements in pulse distributor circuits - Google Patents

Abstract

640,358. Pulse generating circuits. WESTERN ELECTRIC CO., Inc. Jan. 24, 1947, No. 2286. Convention date, Feb. 8, 1946. [Class 40 (vi)] In a pulse generating system for delivering accurately timed pulses in sequence to a number of separate outputs the precision of timing accuracy is increased by the use of a chain switching circuit wherein a lower frequency control source initiates the operation of the firsf pulse generator of the chain and a higher frequency control source terminates the pulse in this and the succeeding generators of the chain, the termination of a pulse in each generator initiating a pulse in the succeeding generator. Fig. 1 shows a pulse generating system in which the output of a crystal-controlled 1024 kc/s. oscillator 22 after squaring in unit 24 is divided down by multivibrators 26, 28, 30, 32, 34, 36 to produce controlling pulses at 256, 64, 32 and 8 kc/s, the 256 and 64 kc/s. pulses being used to control the single-stroke multivibrator chain 1-8 to produce the required sequence of pulses which may be used for sequentially gating signals through to a common load or indicator. The 32 and 8 kc/s. pulses similarly control the multivibrator chain 1<SP>1</SP>-8<SP>1</SP>. The frequency dividing chain of multivibrators 26, 38 &c., Fig. 3 (not shown), comprises a number of identical stages each comprising a pair of pentode valves in which the synchronizing signal is applied to the screen grid of the valves and the cross coupling is effected between the screen and control grids, the control signals A, B and A<SP>1</SP>, B<SP>1</SP> being derived from across the cathode resistors of the multivibrator valves and thus having a 180 degrees phase relationship to each other. Fig. 4 shows the first stages of the single stroke multivibrator chain 1-8, the 64 kc/s. control pulses from multivibrator 32 is applied to terminal c and the control pulses A, B from the 256 kc/s. multivibrator 28 are applied to terminals A, B of Fig. 4. Initially the right-hand section of valve 74 is conducting and the left-hand section is cut-off, a positive going 64 kc/s. pulse is applied to terminal C and a negative 256 kc/s. pulse to terminal A as shown in Fig. 2, this causes the multivibrator to trigger over and at a time prior to that at which the circuit would revert to its normal state if uncontrolled, a positive going pulse at terminal A causes the reversion to be accurately determined. At this reversion to its normal state a positive going pulse is applied from the cathode of valve 74 to trigger off the next multivibrator stage 102 which has been prepared by a negative going pulse applied to lead B. Thus a train of pulses - appear sequentially across the anode loads of the multivibrator as shown in curves 1-8 of Fig. 2. Specifications 510,379, 539,082 and 596,699 are referred to.