Patent GB-841492-A (GB)
Title: Gating circuits employing magnetic amplifiers
Inventor: BONN THEODORE HERTZ
IPC: H03K19/16
Filed: 1957-07-25
Abstract: 841,492. Controlled non-linear inductors. SPERRY RAND CORPORATION. July 25, 1957, No. 23569/57. Class 40 (9). [Also in Group XIX] A plurality of resetting-type magnetic amplifiers are connected in parallel with a load. Several arrangements are described, all of which utilize magnetic cores of material having rectangular hysteresis characteristics such as Orthonik or Moly-permalloy, each core comprising a power and a control winding which are pulsed in different time positions by respective power and signal pulses. A core is normally saturated by the power pulses PP, but if a signal pulse SS is applied in the interval between two power pulses the core flux is temporarily reversed. During the power pulse period when the core is resaturated, the power winding has a high impedance. A coincidence gate is described, Fig. 4, which produces an output pulse in a load only when all the control windings are energized simultaneously. As shown, the load 28 is shunted by three parallel circuits each comprising a power winding 32-34 of a core 29-31. In the absence of a signal pulse to one or more of the control windings 39, the associated power winding is of low impedance and the load is short-circuited. Only when the signal pulses from sources SS-1 to SS-3 are applied simultaneously do all the power windings achieve a high impedance so that a PP pulse from the power source 16 passes to the load. Positive restoration of the core fluxes to their initial saturation state following the reception of control signals is effected by setting windings 41 which are energized from source 40 during the operative periods of the PP pulses. The coincidence gate may alternatively provide an output only when the signals are simultaneously absent. This gate is illustrated in Fig. 5 in which the signal sources are switches SS-1 to SS-3 in the circuit of a pulse source PP-2 operative alternately with PP-1, and the cores are biased by potentials 52, 54, 56 connected to the control windings 39. The gate is otherwise the same as that shown in Fig. 4. In operation the flux in each core is automatically reversed by the bias each time a power pulse PP-1 terminates, and the associated power winding present a high impedance to the next power pulse which then passes to the load. If, however, one or more of the switches are closed, the associated bias is neutralized by the PP-2 pulses and the core flux is unchanged. The power winding then short-circuits the load. In this arrangement the setting windings 41 to 43 are energized directly by the source 16 over a high resistor 44. A further modification of Fig. 4 is described, Fig. 9, in which a complementing magnetic amplifier 10 of the resetting type is connected between the power pulse source PP-1 and the load 28, the power winding of the amplifier being energized by pulses PP-2. An alternative arrangement, Fig. 10 (not shown), has a complementing magnetic amplifier connected between each signal source and its control winding, the signals being supplied from the power pulse source PP-1, and the PP-2 source energizing the amplifiers. A gating circuit may alternatively comprise series-connected power windings 65, 66, 67, Fig. 6, which short-circuit a load 61 only when the signals SS-1 to SS-3 are simultaneously absent. If one or more signals are effective, the corresponding power windings have a high impedance to the next power pulse and an output is developed in the load. A modification is described, Fig. 7 (not shown), comprising switches and bias sources in the signal circuits which provides an output for all input conditions except when the switches are closed simultaneously. Another arrangement is shown in Fig. 8 in which five cores have their windings 81-85 connected in a series-parallel network across the load 86. In this circuit the load is energized by power pulses from source 80 only when all the branch circuits have a high impedance, e.g. when pulses from signal sources SS-1 or SS-2, SS-3 and SS-4 or SS-5 are applied simultaneously. The control windings of this circuit may be biased as in the Fig. 5 arrangement, so that the converse input conditions are necessary to establish an output. A two-core coincidence gate may be used in a binary halfadder circuit, Fig. 15. As shown, the pulses to be added pass from leads 130, 131 over non- complementing and complementing magnetic amplifiers 262, 153 to a complementary sum output lead 137, and are also applied to the control windings 174, 175 of the gate. When both control windings are energized simultaneously, the power windings 172, 173 present a high impedance to the next power pulse from a source PP-1, and an output pulse passes through a non-complementing magnetic amplifier 139 to the carry lead 139b. A pulse is also transmitted to the sum lead 137 over a rectifier 139a to indicate the loack of a sum. A second pulse source PP-2 which produces pulses alternating with PP-1 energizes the amplifiers 135 and 139. Positive setting of the cores after a control signal is applied is effected by windings 41 and 42.