Patent GB-1139567-A (GB)
Title: Apparatus for sampling and storing an applied signal
IPC: G06G7/186
Filed: 1966-03-23
Abstract: 1,139,567. Sampling and storing circuits. APPLIED DYNAMICS Inc. 23 March, 1966 [28 May, 1965], No. 12816/66. Heading G4G. Structure. In apparatus for sampling and storing analogue signals, two inputs at 101, 102 are summed at 104 over equal parallel RC circuits R101, C103, R102, C104, and an initial condition signal is applied to input IC. Summation point 104 is connected to the input of amplifier U1 over switch ES and to the output over resistance R103 equal to R101, R102, while the input and output are shunted by capacitor C101. The amplifier output over resistance R105 to point 105 is connectible to the input of amplifier U2 over switches K2, K3 and directly to its output over resistance R106, while the input and output are shunted by capacitance C102. The initial condition signal is connectible over switches K1, K3 to the input of U2, and directly to the output 106 over resistance R107. The output of U2 is connected over resistance R108 and feedback amplifier U3 to an inverted output at 109, with further feedback over resistance R110, variable capacitance C105, and resistance R111 shunting point 105 to earth. An input terminal may be connected to sample either output 106 or 109 for iterative computation. Amplifiers may be vacuum tube or solid state, and the circuit is particularly applicable to command resetting of analogue integrators. Operation. When switch ES (which may be electronic) is closed, amplifier U1 follows the sum of the input signals and when it is opened a steady output representing the sum of the inputs at opening is held, after a time constant determined by R103, C101, similar to those of C103, R101, and C104, R102. When relay contacts K1, K3 close and K2 is open the ouputs at 106, 109 are driven to signals of opposite sense and equal magnitude to the initial condition input signal, after a time constant determined by R107, C102. When contact K3 is open, amplifier U2 receives no input and the output at 106, 109 remains held at a constant level. When a sampled signal is to be transferred from U1 to be held in U2, switch ES is opened for approximately 4 ms and contacts K2, K3 are closed for approximately 3À5 ms. U1 holds the input value on opening, and this sampled value is transferred to U2; the outputs responding proportionally. Positive feedback over R110, C105 to point 105 increases the speed of response of U2. At approximately 3À5 ms after their closure relays K2, K3 open and amplifier U2 holds the transferred sampled signal, while at approximately 4 ms after its closure switch E5 closes, and amplifier U1 is returned to its input sampling function. Switching logic. Switches K1 K2, K3 may be highspeed magnetic reed relays, and with switch ES are controlled by inverting OR gates G1 to G5 and single multivibrators SS1, SS2 controlled by 0 logic signals of -6 volts and 1 logic signals of 0 volts at terminals OP and TR. At initial reset with 0 logic at OP, switches ES, K1, K3 are closed and switch K2 open. G1 feeds 1 logic to SS1 which is held unfired and feeds 1 logic to close ES. G2 inverts 0 logic at OP to energize relay K1, while a logic 1 signal from G1, a logic 0 signal from G4, and a logic 1 signal from G5 energize relay K3. To switch to " operate mode " in which switch ES is closed and K1, K2, K3 are open, a logic 1 signal at OP and G1 feeds a logic 0 signal to SS1 which remains inoperative, applying a logic 1 signal to close ES. A logic 0 signal from G2 de-energizes K2, and a logic 1 signal from G4 and a logic 0 signal from G5 deenergizes K3. Application of a zero-to-one logic transition to TR with a logic 1 signal to OP switches the circuit to its transfer mode with ES, K1 open and K2, K3 closed. A logic 0 signal from G2 de-energizes K1 and a logic 0 output from triggered multivibrator SS1 of duration 4 ms. opens ES for that interval, while SS1 fires multivibrator SS2 and feeds a logic 0 voltage to G3 providing a logic 1 signal to operate K2. A logic 1 signal from SS2 provides a logic 0 signal from G4 and a logic 1 signal from G5 to energize K3. Multivibrator SS2 resets 3À5 ms. after trigger, and releases K2, K3.