Patent GB-774108-A (GB)
Title: Improvements relating to electrical computing apparatus
Inventor: LIEBMANN GERHARD
IPC: G06G7/46
Filed: 1953-05-18
Abstract: 774,108. Electric analogue calculating systems. ASSOCIATED ELECTRICAL INDUSTRIES, Ltd. April 28, 1954 [May 18, 1953], No. 13931/53. Class 37. In electric analogue computing apparatus of the kind. described in Specification 684,989, the analogue voltages applied to the respective network mesh points are derived from an array of separate resistance potentiometer elements having sliders mechanically operable from a remote position and provided with revolution counters operated from the respective potentiometer drives to decimally indicate the slider voltages of each potentiometer; it being possible to provide two alternatively adjustable potentiometers as voltage sources for each network mesh point; one of which is connected in circuit to supply voltage while the other is being reset to the voltage existing at the corresponding network junction. Fig. 1 shows a pair of potentiometers associated with a single mesh point of a network as described in the above Specification, comprising parallel straight resistance wire potentiometers A, A<SP>1</SP> energized by a voltage Vo and contacted by sliders B, B<SP>1</SP> movable along conductive rods C, C<SP>1</SP> by stretched strings D, D<SP>1</SP> running over pulleys rotatable on the spindles of revolution counters G, G<SP>1</SP> decimally indicating the slider voltages, which are adjustable by friction wheels H, H<SP>1</SP>. The latter are alternatively engageable by a friction wheel I rotatable on shaft K in a rocking mounting L. Operating knob M is normally held disengaged from shaft K and is engageable therewith by pressure against a spring to close contact O; an indicating disc P also being actuated and retained by catch Q after release of knob M, and the slider position of the appropriate potentiometer being indicated by counter G or G<SP>1</SP>. The position of shaft mounting L is linked with the operation of the potentiometer changeover switch S<SP>1</SP> while switch 0 corresponds to switch S<SP>2</SP> both shown in Fig. 2 of the above mentioned Specification; whereby the slider B of potentiometer A under adjustment by knob M is connected to a bridge balance circuit for adjustment to the next corresponding network voltage and the slider B<SP>1</SP> of the already adjusted potentiometer A<SP>1</SP> is connected to the appropriate network point over an isolating resistance. Indicator P is retained by catch Q after releae of knob M until the potentiometer changeover switch is operated. The potentiometers may be circular, and the pairs corresponding to each network point may be mounted in a single assembly for simultaneous operation of the changeover switches and the transfer of the adjustment drive from one to the other, so that the first potentiometer of each network point is successively adjusted to equality with the voltage thereat, after which a simultaneous changeover is effected so that the second potentiometer of each network point is  connected for readjustment while each first potentiometer is connected operatively in circuit. Fig. 2 shows a modification wherein two source potentiometers P<SP>1</SP>m and P<SP>11</SP>m correspond to potentiometers P and P<SP>1</SP> shown in Fig. 2 of the above Specification, Sm is a multiganged switch connecting the sliders of P<SP>1</SP>m and P<SP>11</SP>m alternatively to the various mesh points xo &c. of the network through resistances Ri, and to the balancing circuit for the appropriate network point through switch Slm. The slider of the potentiometer not connected to the mesh point over Ri is connected. in series with balance responder M, which may be a meter for manual or a servocontrol device for automatic balancing of the appropriate potentiometer against the voltage at the mesh point xo &c. A further measuring circuit comprising a potentiometer B associated with a printing counter PC is controlled by a balancing servomotor SM to measure and record the voltages successively appearing at the mesh points. Initial values are set in manually on potentiometer B with switches S<SP>11</SP>m open, and the P- potentiometers are automtically balanced thereto, after which switches S<SP>11</SP>m are closed and the automatic balancing cycle started,