US2955201A

US2955201A - Sequential electronic switch

Info

Publication number: US2955201A
Application number: US632447A
Authority: US
Inventors: Henry T Miller
Original assignee: Collins Radio Co
Current assignee: Collins Radio Co
Priority date: 1957-01-04
Filing date: 1957-01-04
Publication date: 1960-10-04
Anticipated expiration: 1977-10-04

Description

Oct. 4, 1960 H. T. MILLER 2,955,201

SEQUENTIAL ELECTRONIC SWITCH Filed Jan. 4, 195'! /2 C o/v TROLLED Lon o CONTROL. L. ED

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6 /3 0 -/00 l/ BIAS INVENTOR. HEN/Qy T MILLER L) T TOR/WE 45 United States Patent 2,955,201 SEQUENTIAL ELECTRONIC SWITCH Henry T. Miller, Honolulu, Hawaii, assignor to Collins Rfatllio Company, Cedar Rapids, Iowa, a corporation 0 owa Filed Jan. 4, 1957, Ser. No. 632,447

2 Claims. (Cl. 250-27) This invention relates to electronic switches and more particularly to electronic switches for sequential operation.

It is well-known to control appropriate loads by ionizing gaseous discharge tubes. This invention provides an electronic switching control for gaseous discharge tubes which permits rapid sequential control by the tubes over various loads. One application of this invention uses the gaseous discharge tubes to provide clickless keying of amateur radio equipments. This keying is accomplished by having one gaseous discharge tube control the on-ofi operation of the receiver, and one gaseous discharge tube control the on-off operation of the associated transmitter. The receiver and transmitter must be turned on and oif in desired sequences for break-in keying.

It is an object of this invention to control two loads with gaseous discharge devices where the loads are to be turned on or ofl in desired and predetermined sequences. It is a still further object of this invention to provide for two gaseous discharge devices with only one timing circuit to control the sequential ionization and deionization of these discharge devices. It is still another object of this invention to control two loads with gaseous discharge devices where only one extinguishing means is required for extinguishing the two gaseous discharge devices. It is another object of this invention to have the conduction or ionization period of gaseous discharge tubes controlled simply and economically by one auxiliary tube and one timing circuit.

These and other objects of this invention will become apparent when the following description is read in conjunction with the drawing, in which the single figure is a schematic diagram of one embodiment of this invention.

The controlled loads 4 and 5 in this invention may be any of the well 'known electrical loads which are controllable by voltage such as relays, heaters, lamps, etc. These loads control the on-oif operation of other equipments such as transmitters and receivers. In one specific embodiment of this invention, relay circuits were used as the controlled loads 4 and 5. The relays or loads are operated when current flows in the gaseous discharge is suflicient to cause the voltage applied to the gaseous discharge tubes 6 and 7 from the 300 v. source to be below the ionization voltage. Thus, no current flows through tubes 6 and 7, and controlled loads 4 and 5 are open or closed as desired.

If switch 8 is now closed, bias voltage is gradually applied to the grid 9 of the tube 11. This bias voltage is applied from the negative 100 volt source through the resistance 13 to the grid 9. The gradual changes in the value of the bias voltage are due to the charging of the capacitance 14. As the capacitance 14 is charged to a tubes 6 and 7 respectively. When relays are used, this means that there is a current flow in the winding of the relay to open or close the relay contacts. The switch 8 may be any switch means, or in a specific embodiment, it may be a well-known thermostatic device or a wellknown telegraph key. In operation, when switch 8 is open, as shown in the drawing, no bias voltage is applied to the grid 9 of the tube 11. It is to be noted that other types of electron valves, such as transistors, for example, may be employed in lieu of a vacuum tube 11. With no bias voltage applied to the grid 9, tube 11 conducts, and thus current flows through tube 11. With tube 11 biased so as to conduct, and plate current flowing in tube 11, there is a resultant heavy current flow through the resistance 12. When there is a heavy current flowing through resistance 12, the IR drop across resistance 12 voltage equal to the cutofl bias value for grid 9 of the tube 11, tube 11 ceases to conduct. As tube 11 doesnot cease to conduct instantaneously, the IR drop across resistance 12 decreases and the voltagerises gradually along the resistance 12. The ionization voltage of tube 6 is reached first as the voltage along resistance 12 changes, and tube 6 ionizes and conducts. Subsequently, the ionization voltage of tube 7 will be reached as the voltage alongv the resistance 12 rises, and it also will conduct. The time between the ionization of the two tubes will actually be controlled by the time constant of the charging circuit.

Now when the switch 8 is opened, the capacitance 14 and the resistance 15 form a discharge circuit. The voltage which was applied to the grid 9 will deteriorate slowly due to the time constant of the discharge circuit. This reduction in bias voltage will cause gradual conduction in the tube 11. Conduction by tube 11 will result in current flow through resistance 12. As current flows through resistance 12, the IR drop in the resistance will become greater, and the voltage applied to the tubes 6 and 7 will deteriorate below the value necessary for ionization of the tubes. As a result of this gradually lowered voltage along resistance 12, tube 7 will be extinguished first. Tube 6 will subsequently be extinguished with the time interval dependent upon the time constant of the resistance capacitance circuit including resistance 15 and capacitance 14.

It is obvious that this arrangement can provide clickfree keying where the receiver is turned off by depressing key 8,'and the transmitter is subsequently turned on. As the key is released, the transmitter goes off first, and the receiver is subsequently turned on.

Although this invention has been described with respect to a particular embodiment thereof, it is not to be so limited as changes and modifications may be made therein which are within the full intended scope of the invention as defined by the appended claims.

What is claimed is:

1. A sequential switching circuit comprising an electron valve having electron collector means, control electrode means, and electron emitting means, bias voltage source means, switching means for supplying the bias voltage of said bias voltage source means to said control electrode means to cut oif said electron valve, time delay means for delaying a change of potential of said control electrode means, electron collector voltage supply means, electron collector load impedance means connected between said electron collector means and said electron collector voltage supply means, a plurality of gaseous discharge devices each comprising a cathode electrode and an anode electrode, similar ones of said electrodes of said gaseous discharge devices being connected at different points on said electron collector load impedance means so that as the current through said electron collectorload impedance means decreases as said electron valve becomes nonconductive one of said gaseous discharge devices will become conductive and then a short interval of time later another of said gaseous discharge devices will become conductive so that both gaseous discharge devices are in a conductive condition and as the current through said electron collector load impedance'means increases as the electron valve becomes conductive said other gaseous discharge device will become nonconductive and then a short interval of time later the said one of said gaseous discharge devices will become nonconductive so that both gaseous discharge devices are in a nonconductive condition.

2. A sequential switching circuit comprising an electron valve having electron collector means, control electrode means, and electron emitting means, a bias voltage source means, switching means for supplying the bias voltage of said bias voltage source means to said control electrode means to control the conduction of said electron valve, time delay means for delaying a change of potential of said control electrode means, said time delay means comprising a parallel circuit arrangement of capacitive and resistive means connected between said control electrode means and said electron emitting means of said valve, electron collector voltage supply means, an electron collector load impedance means connected between said electron collector means and said electron collector supply means, first and second gaseous discharge devices each comprising a cathode electrode and an anode electrode, controlled load means connected to the cathode electrodes of said first and second discharge devices, the anode electrode of said first discharge device being connected to a variable tap on said electron collector load impedance means, and the anode electrode of said second discharge device being connected to said electron collector means so that as the current through said electron collector load impedance means decreases as said electron valve becomes nonconductive said first discharge device will become conductive and then a short interval of time later said second discharge device will become conductive so that both discharge devices are in a conductive condition, and as the current through said electron collector load impedance meansincreases as said electron valve becomes conductive, said second discharge device will become nonconductive and then a short interval of time later, said first discharge device will become nonconductive, so that both discharge devices are in a nonconductive condition.

References Cited in the file of this patent UNITED STATES PATENTS 1,728,745 Brown et al Sept. 17, 1929 2,095,124 Cockrell Oct. 5, 1937 2,298,695 Hall Oct. 13, 1942 2,684,440 Wallace et al July 20, 1954 OTHER REFERENCES CQ, May 1948, pages 37, 38 article, Clickless Keying Using VR Tubes, by Mack Seybold.

Pub. L Time Delay Circuits, The C-D Capacitor, vol. 17, No. 3, March 1952, page 7.