US1665936A

US1665936A - Radiodetector

Info

Publication number: US1665936A
Application number: US668554A
Authority: US
Inventors: Slepian Joseph
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1923-10-15
Filing date: 1923-10-15
Publication date: 1928-04-10
Anticipated expiration: 1945-04-10

Description

April 10, 1928. 1,665,936

J. SLEPIAN RADIO nnrscwon Filed 0ct.'15, 1923 \fl F79] 2 O i I Fly; 2. Fly. 3.

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' WITNESSES; INVENTOR I :5 Jose 0b 5/30/00.

W Ki I r ATTORNEY Patented Apr. 10, 1928.

UNITED STATES I I 1,665,936 PATENT OFFICE.

JOSEPH SLEPIAN, OF SWISSVALE, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

RADIODETECTOR.

Application filed October 15, 1923. Serial-No. 668,554.

My invention relates to a transmission of intelligence by electrical means.

Broadly speaking, the object of my invention is to provide a more convenient form of detector for radio frequency signals.

Specifically, the object of my invention is to provide a detector which shall be more convenient to use and more readily kept in adjustment than the detectors of the prior art.

In the prior art of the detection of radio signals, a number of substances have beenfound to have such properties of unilateral. conductivity as to be sensitive to radio signals. In some of these substances, this property is manifested only upon certain areas of the surface of the substance, while with others, the sensitivity is more uniformly dis-' tributed over the material, but is not high.

I have-found that a mixture made up of powdered carborundum, amorphous carbon and a bonding agent such as kaolin or waterglass has the property of changing its effective resistance with a change in applied voltage, that is, its conductivity is non-rectilinear.

ing description and claims, when read in connection with the accompanying drawings,

wherein:

Figure 1 is a diagrammatic View of a radio receiving system embodying my invention.

Fig. 2 is a curve of the apparent change in resistance, with change in applied voltage, of the material forming the detector of my device, and

Fig. 3 is a curve showing the change in current flow with change of voltage applied to the material forming the detector of my device.

In Fig. 1 is shown a receiving system comprisingan aerial 1, a tuning inductance 2, a ground 3, a signal receiver 4, a battery 5, a shunting condenser 6, a detector 7, connector wires 8 and 9 and a potentiometer 10.

The detector 7 consists of conducting plates 11 and 12 on opposite sides of a mass a given current and that an increase in voltage produces more than a proportional increase in current over a range of a few applied volts. 7

In operation, the potential battery 5 is adjusted, by means of the potentiometer 10, until the voltage drop across the mass 14 of detector 7 is such as to bring the current value to the bend of the curve of Fig. 3, indicated by point a. The circuit comprising aerial 1, tuning inductance 2 and ground 3 is then brought into resonance with the incoming signals. Upon the arrival of signals, high frequency is impressed across the terminals of detector 7 by way of connecting leads 8 and 9 and The potential of battery 5 having been adjusted to provide an applied potential across shunting condenser rent t rough the signal indicator 4 and hat-.

tery 5 by virtue of the non-rectilinear conductivity of the detector in the following manner.

If the first half cycle of the high frequency current happens to have a polarity which is additive with the applied voltage of the polarizing battery, raising the voltage to point 0, the increased voltage brings into effect the reduction of resistance with increased voltage, and a current larger than is proportionate to the previous voltage and current will flow from battery 5 through phones 4, detector 7 and the circuit, as shown by point d. The next half cycle of the highfrequency current will be in opposition to the battery voltage and therefore subtractive, producin a voltage corresponding to point e. The lower voltage will bring into play the efl'ectively higher resistance of the etector 7. Since the effective resistance of the material is higher, a reduction in current from battery 5 through signal indicator 4: to point f will occur, which reduction will, however, be proportionately less in value than the increase in current produced by the preceding half cycle. 'In this Way, the presence of a high-frequency current in the circuit influences the average current flowing 'from battery 5, causing an increase in its value equal to the difference between the in crease produced by one half wave over the decrease produced by the other half Wave of the received signal, which occurs during the period of the reception of the signal. The increase of current during the time of the signal produces an effect on the signal indicator 4, therebyrendering the signal perceptible.

In this wa my device, in operation,

gives rectification and detection of incoming radio frequency signals.

body comprising a mixture of carborundum,

amorphous carbon and a binder.

2. A radio detector comprising a body having a non-rectilinear conductivity, said body comprising a mixture of powdered carborundum, lampblack and a bonding agent, said bonding agent comprising sodium silicate.

In testimony whereof, I have hereunto subscribed my name this 9th day of October,

JOSEPH SLEPIAN.