Patent GB-562791-A (GB)
Title: Improvements in or relating to electric impulse generation or regeneration of predetermined duration and amplitude
IPC: H03K5/04
Filed: 1942-12-23
Abstract: 562,791. Electric supply. HADFIELD, B. M. Dec. 23, 1942, No. 18268. [Class 38 (iv)] [Also in Groups XXXVI and XL] In an electric impulse generator or regenerator, a switching device is arranged to cause a reactance to be successively charged or energized over one path from a supply voltage and discharged or de-energized over another path, non-linear circuit elements and biassing voltages or currents being employed to terminate both the charging or energizing of the reactance and the discharging or de-energizing of the reactance at predetermined voltage or current limits. Fig. 1 shows a series circuit comprising a resistance 'Rc, condenser C and resistance Rd connected between the terminals of a battery E, A rectifier MR1 is shunted across the resistance Rd, and a switch S is connected as shown. On opening the switch, the condenser C charges from the battery E through the resistance Rc and the rectifier MR1, which is conducting. On closing the switch, the condenser C discharges through the resistance Rd, the rectifier MR1 being non-conducting. In this circuit the condenser C charges to E volts and discharges to zero, both of which functions take an infinite time. In the modified circuit shown in Fig. 2, a further rectifier MR2 is connected in series with a bias battery e1 across the resistance Rc and a further bias battery e2 is inserted between the resistance Rd and the battery E. The discharge voltage of the condenser C is still zero and on opening the switch S charging proceeds until the condenser voltage rises to E-e1. The rectifier MR2 then becomes conducting and the charging stops. On closing the switch S, the rectifier MR1 becomes non-conducting and the condenser C discharges through the resistance Rd and battery e2 until the condenser voltage falls to e2. The rectifier MR1 then becomes conducting and the discharge stops. The voltages el, e2 may be provided by taps on the main battery E. Since the resistances Rc, Rd independently control the charging and discharging functions it can be arranged that the function which is not utilized as an output takes the lesser time so that the breakdown of the circuit occurs on the utilized function and the maximum output at breakdown is the greatest possible value. An alternative position for the switch S is shown at 81. Fig. 3 shows a circuit for half-wave operation with an alternating input at terminals 1, 2. The input is applied through a transformer T and resistance R1 to the control grid of a pentode VI, which replaces the switch S, Fig. 2, and acts as a high gain amplifier over a very limited input grid voltage range. The anode resistance R2 corresponds to the resistance Rc, Fig. 2, rectifier MR1 replaces rectifier MR2, and the voltage drops on resistances R4, R6 replace the voltages e1, e2, Fig. 2. The resistance R3 corresponds to the resistance Rd, Fig. 2, and the gridcathode path of a second pentode V2 replaces the rectifier MR1, Fig. 2. The valve V2 is switched "off" for a time equal to the discharge time of the condenser C and the anode voltage output on the resistance R9 is a rectilinear positive voltage pulse of the same time duration and of magnitude dependent only on the ultimate anode voltage, which is controlled by a tapping on a resistance R8 and stabilized by a neon lamp circuit R7, N. The mean value of the voltage pulses on the anode of the valve V2 is proportional to the repetition rate, i.e. the frequency, provided the half cyclic operating time of the input is greater than the finite time of discharge. The voltage pulses are converted into current pulses by a cathode follower valve V3, the anode of the valve V2 being connected to the grid of the valve V3 through a rectifier MR2. Positive grid voltage is provided by a, potentiometer R10, R11 and resistance R12. The output load L may be preceded by a filter F, but this may be-dispensed with when a meter with sufficient mechanical inertia forms the load. By duplicating the secondary of the input transformer and the circuit of the valves V1, V2 up to the grid input rectifier MR3, it can be arranged that each half cycle produces an output pulse, so that the output frequency and mean valve will be doubled. For measuring different ranges of frequencies, ranges of condensers in given ratios may be selected by a switch, or the range condensers may be in the required ratios to commercial and the output adjusted to be correct for each range by using separate and adjustable valves for the biasses. In a modification, the valve V1 is replaced by two similar valves connected across the two halves of the secondary winding of the transformer T, so that they act alternately as switches. The apparatus may be arranged as an impulse corrector giving a constant pulse time percentage of the input cyclic time. Such impulse correcting circuits may be applied to the conversion of one pulse system to another, in terms of time or percentage.