Patent GB-1076193-A (GB)
Title: Device having a plurality of stable states of equilibrium
Inventor: SIGORSKY VITALY PETROVICH
IPC: H03K3/02
Filed: 1964-03-26
Abstract: 1,076,193. Multistable circuits; delay lines. INSTITUTE MATEMATIKI SIBIRSKOGO OTDELENIA AKADEMII NAUK USSR. March 26, 1964, No. 13032/64. Headings H3P, H3T and H3U. [Also in Division G4] A multistable state circuit comprises a non- monotonic network having its output fed back to its input, the network comprising a D.C. voltage to pulse duration or delay converter, followed by a pulse to D.C. voltage converter. In Fig. 5, periodic narrow pulses applied to the capacitor pass through the delay line to a gate 13 the collection of which receives a higher frequency wave of sine, sawtooth or other shape. A portion of the wave having an amplitude dependent upon the pulse delay is accordingly applied to a smoothing circuit 15, 16 and the resulting D.C. voltage is applied to the delay line to vary the capacitance of shunt semi-conductor diodes 9 and thus the delay in the lines. A stable equilibrium condition exists whenever the delay is such that the D.C. feedback voltage is equal to the value required to produce the delay and such a condition exists at a different point in each of the cycles of the waveform at 14 between successive input pulses applied to 10. The pulses produced or the D.C. signal represent the state. In Fig. 6 a sawtooth wave is applied at 17 to a regenerative comparator valve which cuts off when the sawtooth wave passes a threshold value determined by a D.C. voltage applied to point 18. The resulting pulse is differentiated by 22, 23 to produce a pulse, delayed with respect to the start of the sawtooth wave and this is used to momentarily open a gate valve 19 to allow a part of a higher frequency sawtooth wave from 24 to pass to a smoothing circuit. The resulting D.C. signal is the threshold voltage of the comparator. Again, there is a point on each of the successive cycles of the higher frequency sawtooth wave at 24 occurring during each cycle of the wave at 17 at which a different stable equilibrium state exists. In Fig. 10 (not shown), 10 c.p.s. pulses are applied (at 36) to a monostable flip-flop (34, 35) and the duration of resulting pulses is controlled by a D.C. voltage applied to the monostable circuit (at point 37). These pulses are differentiated by capacitor (38) and the loss resistance of a harmonic frequency tuned circuit (39, 40) producing pulse pairs spaced in accordance with the variable pulse duration and as these coincide more closely with an odd number of half-cycles of the resonant frequency of the circuit it will oscillate coherently at increasing amplitude at such a frequency (Figs. 8 and 9, not shown). The resulting oscillation is rectified (by 41 and 42) to produce the D.C. voltage for controlling the differentiated pulse spacing. Stable states will exist where the pulse spacing corresponds approximately with a different odd number of half-cycles. In Fig. 14 (not shown), the recovery time of a monostable flip-flop is controlled by a D.C. feedback signal derived from a smoothing circuit but the recovery time is caused to have discrete values by feeding relatively high frequency pulses to the output of the timing circuit of the flip-flop (Fig. 12, not shown), so that the timed period is ended by a particular one of these pulses depending on the stable state to which the whole circuit is set. In an alternative circuit (Fig. 17, not shown), a regenerative Schmitt type circuit has as its input signal the difference between the D.C. feedback signal and a staircase wave (applied at 67). The comparator switches over when the stair-case reaches a particular stair depending upon the stable state to which the circuit is set and remains switched until the end of the staircase so that an output pulse of corresponding width is applied to the smoothing circuit to produce the D.C. feedback signal. The circuits described are set to the desired state by feeding a series of pulses to the forward or feedback circuits or, as in Fig. 17, by applying to terminal 70 pulses of over-riding amplitude and of width corresponding to the desired stable state so that the output pulse width and thus the D.C. feedback signal is driven to the desired stable value. It is stated that the delay element required by the invention could alternatively be a real line or a magnetic tape-recorder.