Patent GB-961550-A (GB)
Title: Electrical oscillatory circuits
IPC: G11C19/12
Filed: 1960-10-31
Abstract: 961,550. Electronic calculating apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. Oct. 31, 1960 [Nov. 6, 1959], No. 37375/60. Headings G4A and G4C. [Also in Divisions H2 and H3] An harmonic oscillation of frequency 2f and with a phase position 0 or IT indicative of a binary value is established in a tuned circuit and is combined with an excitation signal of fundamental frequency f to produce a distorted alternation at that frequency, the harmonic oscillation 2f being sustained by pulses recurring at the fundamental frequency f which are derived from the distorted alternation. Basic circuits. As shown in Fig: 3, a harmonic oscillation established in a series circuit comprising an inductor 6 and a capacitor 7 tuned to resonate at frequency 2f is applied over resistor 11 to a higher amplifier 13, and the amplifier output is combined in a mixer 14 with an excitation signal of frequency f from an oscillator 12. The mixer outputs in leads 15, 16 comprise a distorted waveform the positive and negative halves of which differ in contour as shown in Figs. 4a and 4b, the two figures respectively showing the waveform produced for two opposite phase positions of the harmonic oscillation. Each time the distorted waveform attains a given amplitude, a pulse is produced by a pulse generator 17, 18 responsive respectively to positive and negative values. These pulses are duration controlled by monostable circuits 19, 20 and are applied to the tuned circuit to sustain the harmonic oscillation by way of pulse transformers 8, 9. The equivalent circuit for parallel tuned components 26, 27 is also described, Fig. 6. The circuit may be greatly simplified by the use of a magnetic core 46, Fig. 7, having windings 44, 45 respectively associated with a series resonant circuit 41, 42 tuned to frequency 2f and with an excitation source of frequency f. The core has a rectangular hysteresis characteristic and is switched from one stable state to the other each time the combined currents in windings 44 and 45 of frequency 2f and f respectively provide a sufficient flux-reversing m.m.f. Each time the core is switched a pulse is induced in winding 44 and the harmonic oscillation is sustained. A modification is shown in Fig. 9 in which two cores 49, 50 have series opposed windings in the fundamental frequency circuit to cancel induction in that circuit and so reduce the switching time. In further embodiments, Figs. 10, 11 and 12, the excitation and harmonic oscillation currents are common to a core winding, the oscillatory currents acting in opposite senses around the closed circuits formed e.g. by winding 53, inductor 56 and capacitor 59, and winding 54, inductor 57 and capacitor 59. A modification of Fig. 7 is shown in Fig. 13 in which two series-resonant circuits 66, 67 and 68, 69 are connected in parallel and are respectively tuned to frequencies f1 and f2 where f1 + f2 = 2f. Fig. 14 shows how a harmonic oscillation of chosen phase position is established and detected in a circuit corresponding to Fig. 7. Three input terminals 74, 75, 76 are provided for signals of frequency 2f having phase positions 0 or #. The majority of inputs having the same phase position will exercise control, and provided that the excitation frequency f is applied to terminal 73 a harmonic oscillation will build up in the tuned circuit. An output is then obtained across resistor 79 at terminal 83 having a phase position determined by the majority of input signals. By having one input signal as a reference value, the circuit may function as a logical OR or AND circuit as regards the other two signals. A modified three-input signal circuit is shown in Fig. 15 in which the input and output circuits are inductively coupled to the inductor of the tuned circuit. By using a core biased by current in a winding 84, Fig. 16, the phase condition of the harmonic oscillation may be predetermined. Shifting register. Several of the Fig. 15 circuits 87, 88, 89 may be connected in cascade as shown in Fig. 17. The excitation signals are applied in turn to terminals A, B and C of respective circuit stages, with a small degree of overlap as shown in Fig. 18, for a left to right shift of the harmonic oscillation phase position initially established in circuit 87. #/4 phase shifting circuits 85, 86 between successive stages prevent harmonic oscillation feedback. An alternative embodiment employing the Fig. 9 type of circuit is also described, Fig. 19 (not shown). Binary adder. The quantities A and B to be added and the carry digit R from the previous stage are applied in both true and complementary form to majority circuits 93-96, Fig. 20, each of the type shown in Fig. 9 and having three inputs circuit 90 provides the carry output, and circuits 94, 95, 96 cause a further majority circuit 97 to provide the sum output.