US2086256A - Amplifying circuit - Google Patents

Description

July 6, 1937.. g, ac sm 2,086,256

AMPLIFYING CIRCUIT Filed Feb; 12, 1952 A Patented July 6, 1937 UNITED STATES PATENT, OFFICE AMPLIFYING omourr Harry G. Cisin, Brooklyn, N. Y. Application February 12,- 1932, Serial No. 592,586

13 Claims.

This invention relates to sound amplification and has special reference to an amplifier for deaf persons.

One important object of the invention is toimprove the general construction of devices of Q to provide a novel form of amplifying circuit in which exactly the same circuit is used with alternating current as with direct current, there being no switches necessary to change from one circuit to another as is common in devices intended for use with both alternating and direct current.

With the above and other objects in view, as will be hereinafter apparent, the invention consists of certain novel arrangements of parts and combinations of details hereinafter fully described,

illustrated in the accompanying drawing and specifically claimed.

'In the accompanying drawing the figureshows a wiring diagram of the circuit of this invention. In this drawing there is shown a pair of terminals 10 so that, by means of the usual extension cord (not shown), the device may be connected to thesocket of an ordinary house lighting circuit.

in the circuit there is provided a rectifying tube H and an amplifying tube I2. The tube ii is provided with a filament l3, a grid M, a plate l5 and a cathode l6. The tube I2 is likewise provided with a filament li, a grid I8, a plate |9 and a cathode 20. One of the terminals lilis connected by a wire 2| with one element of a switch 22 used simply for the purpose of turning on and off the current when the device is connected to the house circuit. A wire' 23 leads from this switch to series resistances 24 which are, in turn, connected to one end of the filament l3 by a wire 25. The other end of the filament I3 is connected to one end of the filament I! by a wire 26 and the remaining end of the filament I1 is connected to the remaining terminal I0 by a wire 21. It is of course understood that the resistances 24 are sufficient to prevent burning out of the filaments I3 and I! when the switch 22 is closed. One of these resistances may be a variable resistance if desired.

choke coil 3| is connected by a wire 35 with the terminal 33 and the terminal 34 is connected by a wire 36 with the plate H. The grid I8 is connected by a wire 31 with the movable element of a variable resistance 38 and 'one end of the resistance 38 is connected by a wire 33 with the wire 21. The cathode 20 is connected by a wire 40 with one end of a resistance 4| which has its other end connected by a wire 42 to the wire 33. A microphonic receiver 43 has one terminal connected by a wire 44 with one end of the primary winding-46 of a transformer. The other end of this primary winding is connected by a wire 46 with the wire 39. The remaining terminal of the transmitter 43 is connected by a wire 41 with one end of a resistance. 48 which has its other end connected by a wire 49 with the wire 2?. The secondary winding 50 of the transformer-has one end connected by a wire 5| with one end'of the resistance 43 and its other end connected by a wire 52 to the remaining end of this resistance by connection of the wire 52 to the wire 39.. A condenser 53 is bridged across the wires 39 and 40, being thus in parallel with the resistance 4|. Similarly a condenser 54 is bridged across the-wires 21 and 41, being'thus in parallel with the resistance 48. A condenser 65 is bridged across the wires 2'! and and a condenser 56 is ID are connected by a common extension cord with a socket of an ordinary 110 volt circuit. If

'In the operation of the device the terminals the current is alternating it is immaterial how the connection is made but if direct current is used it is necessary to so make this connection that the wire 2| will be connected to the positive side of the house or other circuit used as a supply. It may therefore be necessary, if the device does not at first work, to turn one of the plugs around in-the usual manner to ensure the wire 2| being positive. The switch being closed, the filaments will be caused to glow and a plate cir cuit will be established through the head set 32 and transformer secondary 50 and this "circuit will, of course, be affected in the usual manner by the action of sound waves on the transmitter 43. Obviously the intensity of action of the receiver head set may becontrolled by adjustment of the variable resistances and. thus the volume of sound received by the person wearing the head set may be adjusted in accordance with the extent of his deafness and the loudness of the voice or other sound desired to be transmitted.

It is intended that the entire apparatus shall be arranged in a compact manner in a suitable carrying case but it is not deemed necessary herein to illustrate or describe such a case since it is obvious that the case may be of any form, material or size which may be found convenient or suitable.

Furthermore, while the invention is primarily designed to assist persons with impaired hearing it will be plain that it may be put to other uses. For instance, the transmitter may be hidden in a room and connected by long leads to the remainder of the apparatus worn by a, person in another room so that the device lends itself to use by a detective. Again the invention may be used as an inter-ofiice or similar communicating device.

Among the advantages of this apparatus may be mentioned that it eliminates all trace of hum when used on a direct current circuit and i'. eliminates all objectionable hum when used with alternating current. The invention permits the use of the M filament 13'l-type A. C.--D. C. humless vacuum tube and permits the operation of the filaments at one-half the rated voltage, thus increasing the useful life of tretube by at least 100%.

There has thus been provided a simple and efiicient device of the kind described and for the purpose specified.

It is obvious that changes may be made in the form and construction of the invention without departing from the material principles thereof. It is not therefore desired to confine the invention to the exact form herein shown and described, but it is desired to include all forms which properly come within the scope claimed.

What is claimed, is:

1. In a device of the kind described, a plurality of vacuum tubes each having a plate, a grid, a cathode and a heater filament, a power supply line leading 'to' the first of said tubes and having the plate and grid of the first tube connected thereto in multiple, a conductive connection between the cathode of the first tube and the plate of the second tube and including in series therewith a choke coil, a second power line, a pair of condensers bridged from the last mentioned-connection to the second power line and connected to said last mentioned connection on opposite sides of the choke coil, a conductive connection including a variable resistance and leading from the grid of the second tube to the second power line, a conductive connection between the cathode of the second tube and the second power line and including a condenser and a resistance in parallel, and a series circuit including the heater filaments and an adjustable resistance connected across the power line.

2. In a device of the kind described, a plurality of vacuum tubes each having a plate, a grid, a cathode and a heater filament, a power supply line leading to the first of said tubes and having the plate and grid of the first tube connected thereto in multiple, a conductive connection between the cathode of the first tube and the plate of second tube and including in series therewith a choke coil, a second power line, a pair of condensers bridged from the last mentioned connection to the second power line and connected to said last mentioned connection on opposite sides of the choke coil, a conductive connection including a variable resistance and leading from the grid of the second tube to the second power line, a conductive connection between the cathallel, and a conductive connection between said power lines and having said filaments connected therein in series, said last conductive connection including a variable resistance interposed between the first power line and the filament 01' the first tube. i

3. In an amplifying circuit operable from an alternating current and direct current source, a first and second terminal connectible to said source; a rectifier tube consisting of anode means, cathode means and heater means, said anode means being connected to said first terminal; a filter having an input and output comprising inductance means and condensersextending trom said inductance means and connected to said second terminal, the inductance lead of said input being connected to said cathode; an amplifier tube comprising an individual envelope enclosing an anode, a cathode and a heater therefor; a translating device, one terminal of said translating device being connected to said amplifier anode and another terminal of said translating device being connected to the inductance lead or said filter output.

4. In an amplifying circuit operable from an alternating current and direct current source, a first and second terminal connectible to said source; a rectifier tube consisting of anode means, cathode means and a heater, said anode means being connected to said first terminal; a filter having an input and output comprising inductance means and condensers extending from said inductance means and. connected to said second terminal, the inductance lead of said input being connected to said cathode; an amplifier tube comprising an individual envelope enclosing an anode, a cathode and a heater therefor; a translating device, one terminal of said translating device being connected to said amplifier anode and another terminal of said translating device being connected to the inductance lead of said filter output; and a resistance, said resistance and said heaters being connected in series between said first and second terminals.

5. In an amplifying circuit operable from an alternating current and direct current source, a

first and second terminal connectible to said source; a rectifier tube consisting of anode means, cathode means and a heater, said anode means being connected to said first terminal; a filter having an input and output comprising inductance means and connected to said second terminal, the inductance lead of said input being connected to said cathode; an amplifier tube comprising an individual envelope enclosing an anode, a cathode and a heater therefor; a translating device, one terminal of said translating device being connected to said amplifier anode and another terminal of said translating device being connected to the inductance lead of said filter output; and a resistance, said resistance and said heaters being connected in series between said first and second terminals, one terminal of said resistance being connected to said first terminal for establishing a voltage drop between said heaters and said first terminal.

6. In a power supply circuit operable .from an alternating current source and direct current source for supplying operating current to a thermionic amplifier section: means for supplying current to the anode circuit of said amplifier section comprising a thermionic rectifier including an anode and a. heater element, the input of said rectifier being conductively connectible to said source, and a filter connected between the output of said rectifier and said anode circuit for smoothing pulsations oi the rectifier output current; and circuit connections for supplying current to said heater element from said source including a resistance individual to the heater circuit for predetermining the current flow from said source through said heater element.

7. In a power supply circuit operable from an alternating current and direct current source for supplying operating current to .a thermionic amplifier section having an anode and a heater element: means for supplying current to the anode circuit of said amplifier section comprising a thermionic rectifier including an anode, a

heatable cathode and a heater element, the anode of said rectifier being connectible to a terminal of said source'and a filter connected between the cathode of said rectifier and said anode circuit for smoothing pulsations of the rectifier output current; and circuit connections for connecting said heater elements in series and to said source including a resistance individual to the heater circuit for predetermining the current flow from said source through said heaters.

8. In a power supply circuit operable from an alternating current and direct current source for supplying operating current to a thermionic amplifier section having an anode and a heater element: means for supplying current to the anode circuit of said amplifier section comprising a thermionic rectifier including an anode, a cathode and a heater element, theanode of said rectifier being connectible to a terminal of said source and a filter connected between the cathode of said rectifier and said anode circuit for smoothing pulsations of the rectifierv output current; and circuit connections for connecting the heater elements to said source including a resistance individual to the heater circuit, one terminal of said resistance being directly connected to said rectifier anode and the other terminal of said resistance being directly connected to said rectifier heater element, for establishing a voltage drop between said rectifier heater and said rectifier anode during current fiow.

9. In an amplifying circuit operable from an alternating current and direct current source: a thermionic amplifier section having an anode circuit; means for supplying current to said anode circuit comprising a thermionic rectifier including an anode and a heater element, the anode of said rectifier being conductively connectible to said source, and a filter connected between the output of said rectifier and said anode circuit for smoothing pulsations of the rectifier output current; and circuit connections for connecting-said heater element in series'with said source including a resistance individual to the heater circuit and connected between said rectifier heater andsaid rectifier anode for producing a difierence in potential betweenvsaidrectifier anode and heater element during current flow.

10. In an amplifying circuit operable from an alternating current and direct current source: a thermionic amplifier section having an anode circuit and a heater element therefor; means for supplying current to said'anode circuit comprising a thermionic rectifier including an anode and a heatable cathode. the anode of said rectifier being directly connectible to a terminal of said source, and a filter connected between the cathode 01' said rectifier and said anode circuit for smoothing pulsations oi the rectifier output current; and circuit connections for connecting said heater elements in series and in conductive relation with said source including a resistance element individual to the heater circuit for predetermining the current flow from said source through said heaters.

11. In an amplifying circuit operable from an alternating current and direct current source: a thermionic amplifier section having an anode, a heatable cathode and a heatable element therefor; means for supplying current to the anode circuit of said amplifier section comprising a thermionic rectifier having an individual envelope enclosing an anode, a heatable cathode and a heater element therefor, the input of said rectifier being conductively connectible to said source, and a filter connected between the output ct. said rectifier and said anode circuit for smoothing pulsations of the'rectifier output current: and circuit connections for connecting said heater elements in series and in conductive relation with said source including a resistance element individual to the heater circuit forpredetermining the current flow from said source through said heaters, said heaters having suitable resistance values to normally heat up their associated cathode electrodes with substantially said predetermined current fiow.

12. In an amplifying circuit operable from an alternating current and direct current source: a thermionic amplifier section having an anode circuit: means for supplying current to the anode circuit of said amplifier section comprising a thermionic rectifierincluding an anode and a heater element, the input of said rectifier being conductively connectible to said source, and a filter connected between the output of said rectifier and said anode circuit for smoothing pulsations of the rectifier output current; and circuit connections for connecting said heater elements in series and in conductive relation with said source including .a. resistance element for predetermining the current fiow from said'source. through said heaters, one terminal of said resistance element being directly connected tosaid rectifier anode and the other terminal of said resistance element being directly connected to said rectifier heater for establishing a substantial difierence in potential between said rectifier anode and rectifier heater during current fiow conditions.

13. In an amplifying circuit operable from an alternating current and direct current source: a thermionic amplifier section having an anode, a heatable cathode and a heater element therefor; means for supplying current to the anode circuit of said amplifier section comprising a thermionic rectifier tube having an individual envelope enclosing an anode, a heatable cathode and a heater element therefor, the anode of said rectifier being directly connectible toa terminal ,of said source.,and a filter connected between the-cathode of said rectifier and said anode circuit for smoothing pulsations oi the rectifier output current; and circuit connections for connecting said heater element in series and in conductive relation with said source including a resistance element individual to the heater circuit for predetermining the current fiow from said source through said heaters, one terminal of said resistance element being directly connected to said rectifier anode forestablishing a substantial difference in potential between said rectifier .anode and said heaters during current flow conditions.

- IIfiRRY G. CISIN.

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