Patent GB-1093462-A (GB)
Title: Pulse generating system
IPC: H03K3/43
Filed: 1965-02-04
Abstract: 1,093,462. Generating predetermined numbers of pulses. BURROUGHS CORPORATION. Feb. 4, 1965 [Feb. 6, 1964], No. 4957/65. Headings H3P and H3T. [Also in Division G4] Pulse trains having a predetermined number of pulses are produced from a free-running generator by control means responsive to the pulses and having a number of selectable current paths, all of which are cut off when the prescribed number of pulses have been produced; adjustable setting means stops the generator when the appropriate number of pulses have been produced. In Fig. 2, a free-running multivibrator 24 (which may use tubes or transistors) is initially biased with tube 118 cut-off by the connection of the grid to the cathode of the magnetically controlled beamswitching tube 28, this also being cut-off. When a start pulse is provided from source 52 (which may be a tube or transistor one-shot multivibrator), this pulse passes through one of the gates 48 (Fig. 3, see below), and returns through one of the lines 202 to a spade electrode of the tube 28. This tube then conducts and the rise in its cathode potential lifts the bias on the grid of 118 and allows the multivibrator 24 to oscillate. At each cycle a count is registered in an electromagnetic counter 32 and pulses are applied to the switching electrodes 82, 82<SP>1</SP>, and target electrodes 70 to advance the beam by one position in the tube 28. When the last position is reached the lower resistance of 96 and 96<SP>1</SP> in parallel does not allow the beam current to be maintained, so that the cathode potential of tube 28 falls to zero and cuts off the multivibrator. Since the number of changes is one less than the number of positions in the tube, the count may (if desired) be made up by triggering the multivibrator to execute one more cycle by a negative pulse from the source 52 applied through diode 150 to the grid of tube 120. Pulse number selector.-The number of pulses depends on the number of electrodes in the tube 28 and on which particular electrode the discharge started; the latter is selected by energizing the appropriate line 202 by the circuit of Fig. 3. The desired number is set up on a programmer 56 (Fig. 2), which energizes one of the leads 190 to a second beam-switching tube 44 (Fig. 3), to determine on which electrode the discharge occurs. If none of these leads is energized the first electrode is fired by reset pulse source 187. Each target electrode is associated with a double-diode gate 194, 198. Normally the upper diodes are biased off by the high positive potential from source V5 applied through resistors 192 and the lower diodes. When one of the electrodes of the tube 44 conducts, the potential of the target 173 falls and biases off the corresponding diode 194, thus removing the bias from the corresponding upper diode 198. A positive start pulse from source 52 (Fig. 2), passes along line 222 and is differentiated by circuits 204, 208 (Fig. 3); the negative spike passes through the upper diode 198 which is not biased, and thence via one of the leads 202 to the corresponding spade electrode of tube 28 (Fig. 2). The number of pulses produced by the multivibrator 24 also depends on which gate 198 is joined to which electrode of the tube 28. Each start pulse from source 52 thus results in the appropriate number of pulses being generated by the multivibrator. The programmer 56 may change this number at predetermined intervals by making the discharge in tube 44 start at a different electrode. The programmer may be a preset counter, e.g. including a beam-switching tube of the type of 28 and 44. All these switching tubes may be replaced by ring or other counters.