US2419340A - Pulse widening circuits - Google Patents

Description

April 22, 1947. EASTON 2,419,340

.PULSE WIDENING CIRCUITS Filed Aug. '7, 1945 Ou fpufi 62:? Rz 8y 12 l I! Inpuf pulses. L

l4- K Voltage across C2 Outpuf Vdlf'agg //i-z,/ I Voltage acruss C4 1/ 'fi J- Z.

INVENTOR. A l 1 an E a st 0 n v At orn ys,

Patented Apr. 22, 1947 PULSE WIDENING CIRCUITS Allan Easton, Long Island City, N. Y., assignor to Emerson Radio and Phonograph Corporation, New York, N. Y., a corporation of New York Application August 7, 1945, Serial No. 609,478

3 Claims.

For many purposes it is desirable to widen narrow pulses of electrical voltage as, for example, for integration purposes. In connection with such widening it is usually desirable, and frequently essential, that the amplitude of the widened pulse be unchanged, or at least continuously proportional to the input pulse amplitude.

The object of my invention is to provide an electrical circuit which will efiect lengthening (widening) of a pulse without changing its amplitude or by making it of any desired amplitude, the extent of the widening being controllable in any desired relationship with respect to the amplitude of the input pulse.

In the drawings Figure l is a circuit vention; and.

Figure 2 is a series of curves illustrating its operation. 7

In Figure i an incoming pulse may be received over the input terminals l, 2. This pulse may, for example, be of one microsecond duration as illustrated by the pulses 3 and 4 of Figure 2. The arrangement of the circuit and the elements used are clear from the drawings, it being necessary to state only that the tube 5 is illustrated as a double diode tube which may be of the GAL5 type having anodes 6, 8 and cathodes 1, 9, and the tube [0 is illustrated as a gas tube-of the 884 type having a cathode ll, grid l2, and anode l3. A vacuum tube could be substituted for the tube I 0 although the performance would not be as good.

In the operation of my circuit, the positive input pulse 3 is received across the input terminals and charges the condenser C2 to nearly the peak value of the pulse through the diode elements 8, 9. This charge is indicated by the curve M of Figure 2. When the pulse input decays to zero the diagram illustrating my incapacitor C2 begins to discharge through the resistance R2. However, the time constant of the resistanceco-ndenser combination R2, Cd is so great that for a relatively long period the charge on C2 remains substantially constant, decaying very slowly.

The voltage across C2 is also impressed simultaneously on the anode l3 of the tube l0 causing the anode to become positive. At the same time, the grid l2 becomes more positive slowly at a rate determined by the time constant of the circuit R3, C4. This rate may be controlled by varying the resistance R3 or the condenser C4 or both, and accordingly varying the duration or width of the output pulse. The condenser C3 is made large as compared with condenser C4 and is used to prevent the charge on condenser 02 from leaking oil through resistances R: and R4.

The potential across C4 is indicated by the curve [5 of Figure 2. When this potential reaches the critical firing potentia the ga in the tube Ill ionizes and C2 is completely discharged through the tube, thus reducing its potential, and the potential of the anode l3, to substantially zero as indicated by the curve It. When this occurs the tube l0 deionizes and the circuit is ready for the next cycle.

The value of the negative bias C and (0+5) is selected to insure that the condenser C2 will be discharged to ground potential and not above or below. If, however, the condenser C2 should be discharged below ground potential so that the grounded plate is positive with respect to the other plate this potential will immediately leak oil through the diode 5 through the path of anode 6 to cathode K and anode 8 to cathode 9.

As stated above, the amplitude of the output pulse may be controlled to have any desired value, for example, a value equal or smaller than the am" plitude of the input pulse. It will be noted that the width of the output pulse may also be made to have a value such that input pulse amplitude where k may be any desired constant, depending on the units used. If k=l the output pulse widt will of course be inversely proportional to the input pulse amplitude.

The tube 5 serves the function or providing a low resistance path of about 200 ohms in shunt to resistance R1 through which the condenser C2 may be quickly recharged to ground potential in the event it discharges to below ground potential, as has been described above. It; also provides for direct current reinsertions so that will be no loss in peak pulse amplitude as theduty cycle is increased.

The delay network Re, C4 could. be replaced with a delay network of a. different type such as a delay multivibrator, or square wave generator. This would make the output pulse Width completely independent of input pulse amplitude.

Approximate values for the various elements shown which may be used in the operation of my invention are as follows:

Output pulse width=- Resistance R4 ..do 7 l It will be understood by those skilled in the art that my invention is capable of various modifications and I do not desire, therefore, to be restricted to the particular details shown and described but only within the scope of the appended claims.

What is claimed is:

1. A pulse widening circuit comprising a condenser which may be charged by an incoming pulse, a delay network connected to said condenser to be operative after a predetermined interval, and a radio tube connected to said delay network'through which said condenser is discharged after said interval.

2. A pulse Widening circuit comprising a condenser charged by an incoming pulse, a delay network connected across said condenser, a radio tube having an anode, grid and cathode with its through which said condenser is charged, a delay network connected across said condenser, a radio tube having an anode, cathode and control electrode with its anode-cathode circuit connected acrosss said condenser and its control electrode connected to said delay network, whereby said condenser is discharged through said anode-cathode circuit after a predetermined interval, and a second diode connected in series with said first diode in a conductive direction across said condenser.

ALLAN EASTON.

REFERENCES cl'rnn The following references are of record in the file of this patent:

UNITED STATES PATENTS anode-cathode circuit connected across said con- Number Name D t denser and its grid connected to said delay n 20 2,179,105 Sidney Nov. '7, 1939 work, whereby a poten ial is impressed upon said 2,320,916 Dawson June 1, 1943 grid to discharge said condenser through sai 2,188,970 Wilson Feb. 6, 1940 ienroge cathode circuit after a predetermined 1n- FOREIGN PATENTS 3. A pulse widening circuit comprising a con- 25 Number Country Date denser charged by an incoming pulse, a diode 548,618 Brit Oct. 16, 1942 Disclaimer 2,419,340.--Allan Easton, Long Island City, N. Y. PULsE WIDENING Cmcur'rs. Patent dated Apr. 22, 1947. Disclaimer filed Mar. 18, 1949, by the assignee, Emerson Radio dc Phonograph Corporation.

Hereby enters this disclaimer to claims 1 and 2 of said patent.

{Oflicial Gazette April 19, 1949.]

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