US2441570A

US2441570A - Method of utilizing crystal oscillators to effect frequency selection

Info

Publication number: US2441570A
Application number: US614342A
Authority: US
Inventors: Jack M Glessner
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-09-04
Filing date: 1945-09-04
Publication date: 1948-05-18
Anticipated expiration: 1965-05-18

Description

- May 18, 1948. J. M. GLESSNER 2,441,570

METHOD OF UTILIZING CRYSTAL OSCILLATORS T0 EFFECT FREQUENCY SELECTION Filed Sept. 4, 1945 qIIJIIIIIlIJ I ll m L w wwmmwk UL E v M1 vs ro max M. 'GLESS/VER ATTORNEY Patented May 18, 1948 METHOD OF UTILIZING CRYSTAL OSCILLA- TORS TO EFFECT FREQUENCY SELECTION Jack M. Glessner, Dayton, Ohio Application September 4, 1945, Serial No. 614,342

2 Claims. (01. 250-36) (Granted under the act of March 3, 1883, as

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a method and means for controlling frequency selection in crystal oscillators and is directed particularly to a system whereby frequency selection is affected by any one of a number of remote control stations.

One object of the present invention is to provide a novel system of frequency selection in which any one of a plurality of crystals may control the oscillation frequency.

Another object is to provide a system of frequency selection in which a plurality of crystals in addition to the controlling crystal may be kept in the oscillator circuit without affecting the operation of the system.

Further objects and advantages of the system will appear in the specification and claims and in the appended drawing in which:

Fig. 1 shows a typical crystal controlled oscillator circuit in which a plurality of crystals are employed.

Fig. 2 shows a system of frequency selection utilizing a plurality of crystals and remote control stations.

The invention herein disclosed depends on a phenomena which may be described as follows: when a second frequency determining element such as a quartz crystal or equivalent circuit is connected in parallel with a first frequency determining element (usually a quartz crystal) of an oscillator circuit already oscillating in response to the first crystal no appreciable change in frequency occurs. Thus it is apparent that the addition of a second crystal does not rob the first crystal of its frequency determining power provided the first crystal is already oscillating when the second crystal is added to the circuit. In experiments I have performed it appears wellestablished that the addition of up to a total of six crystals does not alter the operation; the first crystal to oscillate maintains its control over the circuit regardless of the addition of the other crystals. There is every reason to believe that the system may be extended to include any practical number of crystals.

In Fig. 1 a plurality of crystals I to 6 are arranged with their respective switches II to Hi so that any number of crystals may be placed in the oscillator circuit which includes triode I, inductance 9, variable capacitor 8 and battery III. In the oscillator circuit illustrated in the drawings, well-known means may be used to remotely amended April 30, 1928; 3'70 0. G. 757) vary capacitor 8 to adjust the tuned circuit as the frequency of oscillation is shifted with the use of different crystals. However, an untuned type of oscillator may be substituted, in which the crystal is the sole frequency determining element and no other adjustment for oscillation is required over a wide frequency range. An example of this type of oscillator is found in Patent No. 2,240,450, issued to John M. Wolfskill. If all the switches are closed before the oscillator circuit is closed one particular crystal will always predominate the others and practically instantaneously take control of the circuit and the latter will oscillate at the frequency determined by this one crystal. This random starting of oscillation by the same crystal every time is due, most probably, to the activity of the particular crystal being greater than that of any of the others.

Furthermore, if switch II is closed and the oscillator started crystal I will control the frequency. If, while the circuit is still oscillating, all the switches I2 to It are closed there will be no appreciable change in the frequency of the circuit other than that due to the introduction of slight additional circuit resistance and reactance inherent in the added crystals, crystal holders, switches, and wiring. If now, with crystal I controlling the oscillation and with all switches I I to It closed, all the switches are opened except one, for example, switch I4, and the opened switches are immediately reclosed it will be found that the frequency of the circuit has been shifted and is now determined by crystal 4. Thus the arrangement shown in Fig. 1 is suitable as a means for controlling frequency selection and switches I I to It could be operated in any suitable fashion, such as by relays.

Fig. 2 shows a system such as might be used in aircraft installation whereby frequency selection may be controlled by any one of a number of remote control stations. In this figure crystals I to 6 are provided with switches II to I6 respectively, the switches being operable by solenoids or electromagnetic coils 2| to 26. The representative oscillator circuit includes triode 1, variable capacitor 8, inductance 9 and battery I0. Switches II to I6 are ordinarily closed, as shown, and are opened only upon energization of solenoids or electromagnets 2i to 26. The power source for operation'of the relays is battery 20 and in the system of Fig. 2 any crystal may be made the controlling element from any one of remote control stations 31, 51 and 11.

Remote control station No. 1, shown at 31, includes a rotatable switch member 41 in the form of a split ring and is connected to one terminal of the power source for the relays, which may be any suitable source, although battery 20 has been shown for convenience. Ring 41 is provided with a radial non-conducting portion 48 which is slightly wider than, and operates with, switch contacts 4| to 46 inclusive.

Contacts 4| to 46 are in the circuits of relays 2| to 28 respectively to control the opening or closing of relay contacts II to Hi. In the position shown in remote control station No. 1, contact 43 of relay 23 which controls crystal '3 is in non-conducting position.

Between contacts 4| to 46 and relay coils 2| to 26 are a group of ganged push button switches 3| to 35 respectively which can be closed simultaneously by push button 30. With the rotary switch 41 in the position shown, and assuming the oscilator circuit is energized, pressure on button 30 will close the circuits to relay coils 2|, 22,

24, 2.5 and 26, opening relay contacts ll, l2, l4,

l and I6 respectively and simultaneously, thereby removing crystals I, 2, 4, 5 and (i from the oscillator circuit. Crystal 3 remains in the circuit and controls the frequency of the oscillator. Releasing of button 38 will cause switches 3| to 3.6 to open, .deenergizing

relays

2i, 22, 24, 25 and Z6 and placing all crystals in the circuit, which will continue to oscillate the frequency set by crystal ,3.

Switch 41 may be rotated to any other position and button so may be depressed to change the frequency to that of any other crystal. Likewise

remote control stations

2 and 3, indicated at ST and ll respectively, and which are in parallel with station No. 1 may be set to operate any crystal by rotating switches 61 and 31 and depressing buttons 50 or respectively. In the positions shown in Fig. .2 depression of buttons 50 or m will cause crystals 6 and 2, respectively, to control the oscillator frequency. In control station No. 2 contacts 5| to 65, ganged push button switches .51 to 55, and connection 89 correspond to similar elements in station No. 1, and likewise contacts 8| to 8B, push button switches H to it and connection 39 in control station No. 3.

The frequency selection system described herein oifers the advantage of permitting relatively simple switching .from any one of any number of remote switching positions. As many remote operating positions as desired may be added in parallel connection with the remote control stations already in use without the necessity of altering .the transmitter or receiver circuit, as the case may be, and Without cutting series circuits into the wiring of the apparatus or of any of the remote control stations. Remote control at any station is possible, regardless of the previous tuning affected by any other remote control station.

This is achieved with a simplified relay circuit giving control from various positions independent of prior frequency selection.

It is apparent that the control of frequencies in accordance with the invention as set forth above could be accomplished in many ways by different arrangements of combinations of parts, the specific embodiments shown being presented by way of example only. Therefore I do not intend my invention to be limited in scope or extent except in accordance with the appended claims.

I claim:

1. A remote control system, comprising a plurality of relays each having an actuating coil and a circuit closing contact, each of said contacts opening a circuit when said coils are energized, said coils being connected in parallel, a direct current source, a plurality of switching means simultaneously closed by one control, one end of each of said coils being connected to a first terminal of said source, the other end being connected to one pole of each of said switching means, the other pole of each of said switching means being connected to one of a plurality of brushes, a selector means comprising electrically conductive split ring connecting said brushes to the second terminal of said source, means to rotate said selector means whereby a selected brush connected to any one of said coils through said switching means may be disposed in the split portion of said ring and all other brushes contact said ring, whereby when said control closes said switches all of said coils are energized except the one connected to the'brush disposed in said split portion and all of said contacts open their circuits except the contact in circuit with said selected brush.

2. A remote control system as set forth in claim 1, wherein each of said contacts opens a crystal electrode when said coils are energized, said electrode connecting said crystal in parallel with a plurality of crystals in a variable frequency crystal controlled oscillator.

JACK M. GLESSNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,984,424 Osnos Dec. ,18, 1934 2,073,117 Parkin Mar. 9, 1937 2,240,450 Wolfskill Apr. 29, 1941 FOREIGN PATENTS Number Country Date 314,089 Great Britain May 8, 1930