US1819487A

US1819487A - Electrical frequency stabilizer or time control device

Info

Publication number: US1819487A
Application number: US282222A
Authority: US
Inventors: Smale John Arthur
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1927-06-27
Filing date: 1928-06-01
Publication date: 1931-08-18
Anticipated expiration: 1948-08-18

Description

ELECTRICAL FREQUENCY STABILIZER 0R TIME CONTROL DEVICE Filed June 1-, lea

INVENTOR JOHN mum; sMALE E/L L a (aim ATT RNEY' Patented Aug. 18, 1931 UNITED STATES PATENT oFHcE JOHN ARTHUR SMALE, F BRENTWOOD, ENGLAND, ASSIGNOR TO RADIO CORPORATION OF AMERICA, A. CORPORATION OF DELAWARE ELECTRICAL FREQUENCY STABILIZER 0R TIME CONTROL DEVICE Application filed June 1, 1928, Serial No. 282,222, and in Great Britain June 27, 1927.

This invention relates to electrical frequency stabilizers or time control devices.

- lt is found that with time period devices such as tuning forks, there is a liability for slow and small changes of frequency to ocour and, the present invention has for its principal object to provide means whereby such changes may be corrected automatically under the control of a master time device,

such as a chronometer.

According to the present invention a frequency stabilizer or time control device comprises in combination a time period device. such as a tuning fork, means, such as a damping coil, for increasing or decreasing the frequency of said time period device, a master time device, such as a ehronometer, and means for controlling the damping'coil or its equivalent in accordance with the length of time during which a given'operation of the master time device coincides with a given operation of the time period device, so that the fret uency of the latter device may remain at a su stantially fixed relation to the fre- 5 quency of the master time device.

The invention is illustrated in the accom-' panying drawing in which the single figure shows schematically one way of carrying out the invention.

Referring to the figure the time period device is a tuning fork 1 adapted to be maintained in vibration in the well known way, by means of a coil 2 energized by a local battery 3 in series with a resistance 4 and a contact 5 upon one prong 39 of the fork 1.

The fork is further provided with a second contact 6, preferably adjustable as to period of contact. The said second contact,"

which may be adapted to be closed when the first mentioned contact is open, is connected to the grid 7 of a thermionic valve 8, through a series circuit consisting of a pair of contacts indicated at 9 and adapted to be closed at predetermined intervals (say, every sec- 0nd) by a chronometer 10, a battery 11 (say, 24 volts) whose negative terminal is towards the grid 7, a resistance 12 (say, 4000 ohms), -a'second battery 13 (say, 7% volts) whose positive terminal is towards-the grid, and a second resistance 14 (say 2 megohms). The

multaneously for a period of, say 1/80th of negative terminal of the battery 13 is connected to the cathode 15 of the valve and to a fixed part of the fork through a condenser 16 of'say, 41 microfarads, shunted by a leak resistance 17 (say, .25 megohms).

The anode 18 of the thermionic valve 8 is connected to the grid 19 of a second thermionic valve 20 through a. negative biasing battery 21 of, say, 12 volts, andalso to a common cathode connection through a resistance 22 of, say, 2 megohms, and a high tension battery 23 (say, 50 volts) in series, the said resistance and battery being shunted by a condenser 24; of, say, 5 microfarads. The anode 25 of the valve 20 is connected through a milli-ammeter 26 to a damping coil 27 associated with the tuning fork, thence, through a high tension battery 28 (say, 120 volts) to the common cathode connection 29. The damping coil is so arranged as to speed up the fork when energized and, if desired, a second damping coil 30 energized through a variable resistance31 from thebattery 3 may be provided for purposes of adjustment.

It isto be understood that the numerical values given in the above described construction are by way of example only, and may be varied within wide limits according to requirements.

The operation of the device is as follows- Suppose the correct frequency of the fork is 35 vibrations per second. Then at each 35th vibration, the contact 6 on the fork and the chronometer contacts 9 will be closed sia second. During this period a negative potential will be applied to the grid 7 'of the valve 8 from the battery 11 and, when after the expiration of this period the contacts 9 are opened, the condenser 16 slowly discharges through its shunt resistance 17, thereby causing the grid 7 to return to its normal potential, as determined by. the battery 13, and the value of the grid current. It will be seen that the voltage drop occurring across the resistance 22in the anode circuit of the first valve applies a negative potential to the grid 19, and, since this voltage drop depends upon the anode current, the impression of negative voltage upon the grid 7, by l quency thereof.

reducing the anode current, tends to reduce the negative potential applied to the grid 19, and the said grid therefore tends to take up the positive potential determined. by the anode battery 23 associated with the first is charged to the said potential. By suitably choosing the values of the constants of the two grid circuits, the positive and negative potential excursions of the second grid may be caused to occupy a desired period of time (say five seconds) if allowed to persist to their limits, but, as the contact occurs every second, a mean value of the two excursions results and a substantially constant and mean current dependent upon the second grid potential will flow in the damping coil so long as the duration of coincidence of contact of the fork and the clock remains constant.

If, however, the fork varies its frequency, the duration of contact will be varied and a correction applied through the damping coil. In this manner an average control is exerted by the damping coil tending to keep the average frequency of the fork a constant multiple of the speed of the clock or other master time device.

Having now particularly described the nature of my invention, I declare that what I claim is 1. A frequency stabilizer device comprising in combination a time period device, a master time period device, and means operable in accordance with the duration of coincidence between a given operation of the time period device and the master time period device for increasing or decreasing the frequency of the time period device.

2. A frequency stabilizer comprising a time period device of substantially constant frequency, a master time period device of absolute constant frequency, and means operable in accordance with the duration of coincidence between a given operation of the substantially constant time period device and the master time period device for applying correcting forces to the substantially constant time period device and stabilizing the fre- 3. A frequency stabilizer comprising a time period device of substantially constant frequency, a master time period device of absolute constant frequency, and a thermionic vacuum tube system adapted to become operable in accordance with the duration of coincidence between a given operation of the substantially constant time period device and the master time period device for applying correcting forces to the substantially constant time period device and stabilizing the frequency thereof.

4. A frequency stabilizer system comprising in combination a mechanical vibratory system, a damping coil associated therewith, a master time period device, contacts actuated by both said mechanical vibratory system and said master time period device, and means for controlling said dampingcoil in accordance with the duration of coincidence of the closure of said mechanical vibrator and said master time period device contacts for maintaining the frequency of said mechanical vibratory system at a substantially constant multiple of the frequency of closure of the said master time period device contacts.

5. A frequency stabilizer system comprising in combination a mechanical vibratory system, a damping coil associated therewith, a master time period device, contacts actuated by both said mechanical vibratory system and said master time period device, and means for controlling the effect of said damping coil on said vibratory system in accordance with the duration of coincidence of the'closure of said mechanical vibrator and said master time period device contacts for maintaining the frequency of said mechanical vibratory system at a substantially constant multiple of the frequency of closure of the said master time period device contacts.

6. In a system for maintaining substantially constant frequency of vibratory ele-' ments, a tuning fork, a master time period device and means for increasing or decreasing the frequency of the tuning fork in accordance with the coincidence between the operations of the said tuning fork andthe master time period device.

7. A system for maintaining substantially constant frequency in vibratory elements and the like which includes in combination an electrically driven tuning fork, a master time period device of accurately controlled periodiclty, a vacuum tube associated with said tuning fork, means for controlling the potentials on the control electrode of said vacuum tube in accordance with the periodicity of vibration of said tuning fork and thereby controlling the currentfiow in the output circuit'thereof, and means controlled in accordance with the current flow in the output circuit of said vacuum tube for applying correcting forces to said tuning fork in accordance with periodic variations in the vibration rate of said tuning fork and said constant period master time period device.

8.- A system for stabilizing the frequency of vibratory elements and the like which includes a tuning fork and means for continuously vibrating the same, a master time period device, contacts associated with both said master time period device and said tuning fork and adapted to be closed uponthe vibration of said tuning fork, a vacuum tube adapted to have a negative grid potential thereon controlled in accordance with the comoval of said potential to said second gridwhen the output current of said first vacuum tube decreases, and means controlled in accordance with the strength of the output current in the second of said vacuum tubes for applying correcting forces to said tuning fork for increasing or decreasing the frequencv thereof.

9. A system for maintaining substantially constant frequency in vibratory elements and .the like which includes in combination an electrically driven tuning fork, a master time period device of accurately controlled periodicity, a vacuum tube system associated with said tuning fork and master time period device, means for controlling the potentials on the control electrodes of said vacuum tube system in accordance with the periodicity of vibration of said tuning fork and thereby controlling the current flow in the output circuits thereof, and means controlled in accordance with the current flow in the output circuits of said vacuum tube for applying correcting forces to saidtuning fork in accordance with periodic deviations in the vibrational rate of said tuning fork from that of said constant frequency master time period device.

10. A system for stabilizing the frequency of vibratory elements and the like which includes a tuning fork and means for continuously vibrating the same, a master time period device, contacts associated with both said master time period device and said tuntarding the removal of said potential to said second grid when the output current of said first vacuum tube decreases, and a damping coil associated with said fork and controlled in accordance with the strength of the output current in the second of said vacuum tubes for applying correcting forces to said tuning fork for increasing or decreasing the frequency thereof in accordance with deviations in frequency of said fork from a predetermined multiple of the frequency of said master time period device.

11. In a system for. stabilizing the frequency of vibratory elements, a tuning fork and means for continuously vibrating the same, and a constant period master control device for checking the constancy of vibration' of said tuning fork, a set of contacts connected with said tuning fork and said master control device adapted to be closed upon coincidence of operation of both of said devices, a vacuum tube associated with said tuning fork and having its input circuit include said master time period device, said contacts and said fork, means for applying negative potentials to the control electrode of said vacuum tube for predetermined conditions in the vibration of said tuning fork, a second vacuum tube having its control electrode connected with the output circuit of said first named vacuum tube and adapted to have-.the grid potential thereon controlled in accordance with the strength of current flowing in the output circuit of said first vacuum tube,

means for controlling the rate of change of potential on the control electrode of each of said vacuum tubes, and means for controlling the period of vibration of said tuning fork in accordance with the strength of current flowing in the output circuit of said second named vacuum tube for increasing or decreasing the frequency thereon in accordance with variations between the coincidence of closure of said contacts due to said tuning fork and said master time period device.

JOHN ARTHUR SMALE.

fork and adapted to be closed upon the 1n vigration of said tuning fork, a vacuum tube adapted to have a negative grid potential thereon controlled in accordance with the coincidence between the operation of the tuning fork and master time period device contacts, resistance means for gradually remov-