US2303734A - Key for communication systems - Google Patents

Description

Dec. 1, 1942. 1.. GARCEAU KEY FOR COMMUNICATION SYSTEMS Filed April 2-, 1941 '2 Sheets-Sheet l INVENTOR LUVET 7 EHRCIEHU ATTORNEYS- 1942- v N L GARc l-:Au 7 2 ,303,734

KEY on COMMUNICATION SYSTEMS Filed April 2, i941 2 Sheets-Sheet 2 Lavsrr ERR-CEBU ATTORN EYJ.

Patented Dec. 1, 1942 UNITED STATES PATENT OFFICE q 2,303,134' y KEY FOR coMMoNIcA'rron sxs'rnrrs Lovett Garceau, Holliston,

Application April 2, 1941,- Serial No. saunas 5 Claims. (cine-s2) A This inventionrelates to improvements in keys for communication systems and is directed more- ,particularly to the provision of a key for producing electronically dot, dash, and space intervals of constant timing and mathematically accurate.

Another object of the invention is the provision in combination with a key, of a multi-vibrator having circuits including constants, some of which are adapted to be changed by said key to produce oscillations, the peaks of which are substantially equal to thespaces therebetween,

like allkeys of the bug type uses the easy side i when the key is in one position, and adapted to produce oscillations when said key is in another position, the peak durations of which are substantially larger than the peaks produced when the key is in said first position, the spaces between the oscillations remaining substantially the same for either position of the key.

The electronic circuits herein described includ two triodes which together constitute a relaxation type oscillator which produces substantially square wave forms.

When the grid condensers and the two, grid leaks are equal, the oscillations produced are symmetrical. The durations of the wave produced in the plate circuit of one tube is equal to in the .art.

in another position to complete a circuitafor producing oscillations to be used as ,dashesfl,

a relay having its actuating winding subjected to said oscillations, and having switching means for controlling an external circuit or circuits.

Other objects will be apparent to those skilled by way of example, my new and improved key which may be termed an electronic bug key,

to side motion of a paddle shaped handle. 'Assoelated with the paddle and contacts controlledthereby, is electronic means, the circuit of which is shown in the drawings and will hereinafter be described indetail.

- When the'paddleis pressed to the right with the-thumb a series or succession of dots is produced, the first of which is instituted when conthat produced in the .plate circuit of the other f tube. One of these equal grid condensers is connected to the plate of the other tube by the key when the latter is in the dotting position. When the key is in the dashing position it connects'a condenser of larger capacity between said grid and the plate of the other tube with the result that the spaces between the peaks are the same length as they were between the dots" but the durations of the peaks is increased. When the key is in the middle or neutral position neither of the connectable grid condensers is connected in the circuit, therefore no feedback to dots or vice versa.

tacts associated with the paddle are closed.

This series of dots is continuously instituted as long as the key is closed in that direction. When the paddle is pressed to the left a series of dashes is instituted and'they also are continuous while the key is closed in tha t direction. The reduction in labor of sending is obvious.

The key is movedonly at the beginning and end of a character and to change from dashes The transmission of figures of the, wrist are required for any character.

One of the most important advantages of my new electronic keyis the improvement in the .ac-

/ curacy of sending. It is well known'that characcoupling exists and the multi-vibrator cannot function as such.

Still another object of the invention is the provision of a key which when moved to one position, produces electronically a series of spaced dashes; and when moved to its other position,

' produces electronically a series of spaced dots"i ters are made up of dots, spaces and dashes, the length of which bear definite mathematical relationships. For example, the length of spaces between dots or dashes is supposed to be exactly equal to that of the dots. The length of the dashes is supposed to be exactly equal to theinterval of three dots. A dash plus a following space is equal to two dots plus their following spaces. Very few operators, whether they use the simple ormechanical bug" keys, preserve therewith, said key being adapted, when in one position, to complete a circuit for producing oscillations to be used as dots, and adapted when 55 this relationship withany accuracy.

My improved electronic key makes inaccurate sending impossible. The dots and spaces are automatically made equal. The dashes are also always made three time's as long as thedots and even the spaces'between a dash and a dot or vice versa are made equal to the spaces between dots regardless of how fast the paddle is flipped the continental code is also simplified as only three motions of to above and two other be made by successive individual motions of the paddle.

As is well known in the art, the adjustment of any mechanical bug key is a complex and timeconsuming operation requiring the stopping of transmission to set up a number of diiferentcontact screws and to try out a number of different weight positions. contrasted with this, my new ke can be adjusted instantly even during the process of a transmission. A single knob on the panel when rotated 1110116 direction lengthens and when rotated in another, shortens simultaneously the periods of dot, dash and spaces and at the same time preserves their exact proportion.

By means of this knob I am able to adjust the speed at which the dots and dashes are institutedso that a minimum range of 8 words per minute up to a maximum range of 100 or more words per minute may be obtained.

My electronic key is provided with a small panel upon which is mounted the single knob referred controls-one is the on and oil? switch for the power supply and the other is a shorting switch -which short-circuits the switching means controlled by the internal relay.

. 22. The cathode This is particularly useful for-land line telegraph work where the "circuit is normally closed for reception, and it is also useful for radio applications where the key is to be left closed to hold a channel with a continuous carrier, or to make trans mitter adjustment with the key closed.

There are no mechanical adjustments.

In the embodiment herein shown and described all of the apparatus is housed in a small cabinet approximately the same size as the regular 'mechanical bug key. It requires a power supply of approximately 17 watts at 110 volts, either alternating or direct current.

It is intended for continuous operation and is suitably ventilated to dissipate the heat generated, and the constants of the circuits are unaffected by considerable variation in tube characteristics When my electronic bug key is to be used for the operation of a high power radio transmitter or wherever a radio-frequencycircuit is to be keyed, it may be preferable to employ an additional keying relay. Since my key operates very quietly, a monitoring device may be associated with the transmitter to which my key is com nected. 1

Referring to the drawings:

Figure 1 is a plan view of my improved electronic bug key showing the arrangement of the elements; 7

Figure 2 is a left side elevation of the key;

Figure 3 is an end elevation of the key showing the front panel and the controls thereon; and,

\ Figure"! is a circuit diagram showing the internal connections of the various elements of my new electronic bug" key.

, Considering first Figure 4, the tube 29, which may be, for example, a type 12807, is employed as a rectifier. The device also includes tubes 2| and 22, which may be, for example, types 12SJ7.

A connector plug 23 is providedfor connecting the device to a source of current, and has one conductor 24 connected to the heater 25 'of the tube 75' meral 15, and the arms 55 -11 and a second conductor 83 22, and this heater is in turn connected via wire 26 to the heater 21 of tube 2|. A conductor 28 connects heater 21 to a resistor 29, the other end of which is connected via wire 38 to serially connected heaters 3| and 32 of tube 20. The heater 32 is connected via wire 33 to switch 34, the other side of which is connected via conductor to. the plug 23, so that.when the plug 23 is'connected to a sourceof current the switch may be closed to complete the heater circuit.

The platesand grids of tube 20 are tied together to form an anode 36. The cathodes 31' are tied together and connected via wire 38 to the choke 39. The ends of the choke 39 are by-passed by filter condensers 40 and 4|, the positive terminals of the -condensers being connected to the ends of the choke. The negative terminals of the condensers 40, 4| are connected together and are connected via the wire 42 to the cathode 43 of the tube 2| and thence to the cathode 44 of the tube 44 is in turn connected to the conductor 24.

The plate, 'screen'grid and the suppressor grid of the tube 2| are tied together to form an anode 45 thereby, forming ofthe tube 12SJ'1 a. low-mu triode. This anode is connected to the high voltage conductor 46 through a resistor 41, by-passed by a condenser 48; The anode 45 is also connected via a condenser 49 and a wire 50 to the cone trol grid 5| of the tube 22. v is also connected to a fixed resistance 53 which is in turn connected to the variable resistance 54. An arm 55 engages, the resistor 54.

The grid 52 is connected to a fixed resistance '56 which is in turn connected to a variable resistor 51. The arm 58 engages the resistance 51. The arms 55 and 58 are connected together and to the cathodes 43 and 44 via wire 59.

The variable resistances 54 and 51 in practice are incorporated in a twin volume control which may be generally designated by the nuand 58 move in unison so that the leak resistances between the grids and the cathodes are substantially equal throughout the range of movement.

. The grid 52 is also connected via a wire 60 to the moving arm 6| of a double throw switch. The plate, the screen and the suppressor grid of the tube 22 are connected together to form an anode 62 thereby making the 128.17 tube a lowmu triode. This anode is connected via a wire 53 to one terminal of the actuating winding 54 of a relay. The other terminal of the actuating winding is connected via a wire 65 to a high voltage line 46. The actuating winding 64 is bypassed by a suitable fixed resistor connected to the'anode' A wire 61 has one end wire-63 and its other end commonly connected to capacitors 68 and 69. 1

The capacitor 68 is connected to the terminal 10 of the double throw switch, and the capacitor 69 is connected to the other terminal 1| of the double throw switch. The movable arm 12 of the relay 64 is urged against the contact point 13 by spring means 14, and when the relay is energized the arm 12 is attracted and brought into contact with the contact point 16. r

The arm 12 is connected via a wire 11 to an output terminal 18, and a'wire 19 connects the 8| has one conductor 82 connected to the wire connected to the wire 19 so that when desired, the switch 8| can be thrown to short circuit the output terminals 18 and 80.

The control grid 5| V The resistor 66 across the relay winding 64 is provided for eliminating the inductive kick from the winding which kick would spoil the symmetry of the circuit. I have found that a resistance of 4000 ohms is suitable for this purpose. The plate load resistor 41 in the embodiment shown, is 5000 ohms resistance and the condenser 48 shunting this resistor is .004 microfarad capacity for the purpose of stopping high frequency parasites occurring when the key is open and which radiate into radio receivers.

Referring now to Figures 1 to 3, it will be noted that the base plate 84 supports the apparatus and this base plate is substantially the area of the base of any ordinary mechanical type bug" key.

A front panel 85 is secured to the front end of the base 84 and forms a support for the switches 84 and 8|, the twin volume control 'l5and the paddle key 86. A knob 81 secured to the shaft of the twin volume control is readily accessible for changing the transmitting speed and is provided with a pointer 88. The paddle key 86 is pivotally mounted on the panel 85 and is operatively connected to the movable arm 6| of the double throw switch.

A rear panel 89 is mounted on the base 84 and a suitable cover 90, Figure 5, for enclosing the mechanism, may be secured to the edges of the panels 85 and 89.

Spaced apart from the rear panel 89 is an upright wall 9| which forms a support for the tubes 20, 2|, 22 and for one end of the resistor 29. The other end of the resistor 29 is supported by the panel 89. The condensers and resistors may be grouped between the sockets of the tubes 20. 2| and 22 and the other mechanism, as shown in Figures 1 and 2.

In Figure 5 it will be noted that the cover 90 has a plurality of ventilating holes 92 formed in the wall above the tubes and resistor 29, through which heat may pass and other holes 93 near the base through which cool air may enter the interior.

The base plate 84 may have rubber feet 94 mounted thereon so that the device will not skid while in use.

In the commercial form of the device a suitable connector cord carrying a plug 23 is provided, and a cable 95 extends outwardly from the terminals 18 and 80 for connection to the circuit to be controlled.

Operation To operate my electronic bug key, the opera tor turns on the switch 34 and in a few seconds the heaters in all of the tubes are hot.

When the operator presses the paddle 86 to the right with his thumb, as stated before, a succession of dots is produced and when the paddle 86 is pressed to the left a series of dashes is produced.

Referring to Figure 4, it is assumed that when the paddle is moved to the right the lever 6| is moved into contact with the point 10. The capacity of the condenser 68 is .1 microfarad.

When the lever 6| contacts 10 and the anode 62 of the tube 22 is capacitively coupled to the grid 52 of the tube 2|. The grid 5| of the tube 22 is permanently coupled to the anode of the tube 2| through the condenser 49, the capacity of which, for example may also be .1 microfarad.

When the key is thrown to the dotting position the lever 6| contacts the contact 10 thereby coupling the grid 52 to the plate 62, and the condensers 88 and 49 being of the same capacity the multi-vibrator produces symmetrical oscillations.

Now, when the paddle is moved to the left and the lever 6| is brought into contact with H, the condenser 69, which, for example, may have a capacity three times as great as that of the condenser 68, causes the peaks of the oscillations to be approximately three times the duration of the peaks produced when the key is in the dotting position. The spaces between the peaks are the same as the spaces dots are produced. The relay connected to the output of the multi-vibrator operates slower and thereby causes dashes in the external circuit connected to the cable 95.

As pointed out above, the intervals between the dots, and also the intervals between the dashes are substantially equal to the life of a dot, and the intervals of the dashes is substantially equal to the life of three dots. A dash plus a following space is equal to two dots plus their following spaces.

From the above it can be seen that an operator who is used to the mechanical type of bug key can very quickly learn to use my electronic key and can, with my key, transmit rapidly, accurately and uniformly, and by means of the knob 81 he can set the device to transmit at any speed from 8 words per minute to a maximum of or more words P r minute.

Although I have herein shown and described, by way of example, one embodiment of the invention which is understandable to those skilled in the art, it must be understood that many changes may be made in the arrangement herein shown and described without departing from the spirit of the invention as set forth in the following claims.

What is claimed is:

1. In a keying device, a unitary structure comprising a base, a thermionic multi-vibrator mounted on said base for producing triggered impulses, a power pack on said base including a rectifier tube and a filter system, means for connecting said power pack to a source of current, keying means on said base, switching means controlled by said keying means, connections between said switching means and said mu1tivibrator including constants to effect the production of impulses representing dots when said switching means is in one position and the production of impulses representing .dashes when said switching means is in another position, a relay having its magnet winding connected to receive said triggered impulses, a second switching means on said relay controlled by said magnet and adapted in turn to be connected to an external circuit, a panel mounted on said base and forming a pivotal support for said keying means,

- the latter having its inner end conected to said first switching means and having its outer end projecting from said panel so as to be accessible to an operator, a casing secured to said base and said panel and embracing all of the above-mentioned parts except the projecting end of said keying means, a connector cord extending through said housing for connection to a source of current, and a second connector cord extend- .ing through said housing from said second switching means.

2. Ina keying device, a unitary structure comprising a base, a thermionic multi-vibrator on said base for producing triggered impulses and between the peaks when switching means and including a power pack and means for connecting the same to av source of current, switching means, connections between said switching means and said multi-vibrator including a capacitance of one value adapted to eil'ect the production of triggered impulses of one periodicity when said switching means is in one position and a second capacitance of a diiierent value adapted to effeet the production oi triggered impulses of a difl'erent periodicity when said switching means is in another position, a relay having its magnet winding connected to the output of said thermionic means, a second switching means on said relay controlled by flux generated in said magnet by said triggered impulses and adapted to be connected to an external circuit, a housing secured to said base and enclosing all said parts, and keying means projecting from said housing and connected to said switching means.

3. ma keying device, a unitary structure comprising a base, a thermionic multi-vibrator mounted on said base, a power pack on said base for supplying power to said multi-vibrator, switching means, connections between said said multi-vibrator including a capacitance adapted to cause said multivibrator to produce triggered impulses of a predetermined periodicity when said switching means is in one position, and a second capacitance adapted to efiect the production of trigchanging the includes a control knob on tact means.

gered impulses of a periodicity diiierent from the periodicity of said first impulse when said switching means is in its other position, the spaces between both kinds of said impulses being substantially equal, a relay having its magnet winding connected to contact means on said relay controlled by said magnet and adapted to be cuit external to said device, 'a control panel on said base, and a casing secured to said base and to said control panel and forming a housing enclosing all said parts, and keying means pivotally mounted on said panel and having its'inner end connected to said switching means and having its outer end projecting outside of said housing.

4. A keying device according to claim 3 which said panel adjacent to said keying means, and twin variable resistors movable by said knob and connected to the control grids 01' said multi-vibrator for coniointly rate of said periodicity.

5. A keying device according to claim 3 in which said power pack includes a power circuit connectible to a source of current, switching means being provided on said panel for controlling the supply of energy to said circuit and in which a second switching means is mounted on said panel and adapted to short circuit said con- LOVE'I'I GARCEAU.

receive said impulses, r

connected to a cir-

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