US2108154A

US2108154A - Receiver tuning circuits

Info

Publication number: US2108154A
Application number: US93354A
Authority: US
Inventors: Carel Jan Van Loon
Original assignee: Philips Gloeilampenfabrieken NV
Current assignee: Koninklijke Philips NV
Priority date: 1935-08-20
Filing date: 1936-07-30
Publication date: 1938-02-15
Anticipated expiration: 1955-02-15
Also published as: FR809653A; BE417050A; DE687209C; NL54190C; GB467771A

Description

Feb. 15, 1938. I c. J. VAN LOON 2,108,154

RECEIVER TUNING CIRCUITS Filed July 30, 1936 ams/e KNOB FREQUENCY c e d 3 9 r0 1. F. AMPUF/ERH 4 /2 T DC- v INVENTOR CAREL JAN VAN LOON BY I v M ATTORNEY vention is, however, primarily intended for a amplification of the low-frequency oscillations the accompanying drawing.

Patented Feb. 15, 1938 UNITED STATES PATENT 'QFFICE RECEIVER TUNING CKRCUITS Application July 30, 1936, Serial No. 93,354 In Germany October 26, 1935 11 Claims. (01. 250-40) This invention relates to a circuit arrangement grid 2 of a pentode 3. The screening grid is for assisting the tuning of wireless receiving sets. connected to a point of a resistance I8 by which Such arrangements are particularly desirable for the voltage supply leads are bridged. The cathsets having automatic volume control, since in ode is connected to the negative conductor by this case it is often very difficult for laymen to way of a resistance which provides negative grid find the point of correct tuning. The circuit bias. The output circuit of the valve includes a arrangement according to the invention serving circuit 4 which comprises an inductance and a for assisting tuning is set into operation upon capacity and which may be tuned to the interaccurately tuning to the desired carrier wave. mediate frequency, although as an alternative an The tuning may be assisted, for example, in that aperiodic circuit may be used. The voltage acan optical device is set into operation upon the tive in the output circuit is supplied via a concorrect tuning being reached, or in that not until denser 5 to a rectifier B, l which jointly with two this moment the low frequency amplifier part of resistances 2 b and I3 constitutes a closed direct the set is caused to become operative. The incurrent circuit. The output circuit of the tube 3 is in addition coupled via the condenser 8 to a circuit 9 of low damping tuned to the intermediate frequency carrier wave. The voltages occurring in this circuit are supplied to the rectifier i, H, and bring about a voltage drop across the resistances i2 and H3 in such manner that the upper point of the resistance l2 becomes negative relatively to the lower.

The two rectifiers may be separated from each other, but preferably, as shown in Fig. 1, they are housed in a single bulb and have one common cathode. As shown in Fig. 1, the resist ance I3 is included in both rectifier circuits. The resistance it constitutes the input circuit of a rectifier valve M, the output circuit of which includes a magnetic braking device I5 which, as will be described hereinafter, prevents any further movement of the tuning knob ll upon the correct tuning of the latter to a carrier wave. For this purpose, the shaft of the knob has mounted on it a braking disc it of soft iron. Instead of using a magnetic braking device, it is also possible to use an electrostatical one.

The device operates as follows:

When the grid of the tube 3 has not supplied to it signal voltages, neither of the two rectifiers carries current and the grid of the valve M has such a potential that a current fiows in the anode circuit. The magnetizing effect of this current is neutralized by a constant current passing through a second coil H5, or by a permanent magnet, so that the tuning knob can be moved freely. Now, when approaching to the point of correct tuning, a voltage first occurs through the circuit 4 so that a rectified current flows through the resistances 24 and I3. The voltage drop across the resistance !3 is such that the upper point of this resistance becomes positive relatively to the lower one. When approaching still more to the correct tuning, a voltage will also occur across the second circuit 9. Due to the device in which upon correct tuning further rotation of the tuning member is prevented, for example, by a brake being brought into operation.

According to the invention, two rectifiers are coupled to the highfrequency or intermediatefrequency amplifier in such a manner that one of the rectifiers is preceded by greater selectivity than the other. In addition, the rectifiers are connected in such a manner that the rectifier voltage of one rectifier influences the other in such a manner that this latter rectifies only in the immediate vicinity of the resonance frequency and that the rectified current of this rectifier is used for the control of the device by which tuning is assisted.

Preferably, the part of the receiving set that assists tuning solely serves this purpose and rectification of the high-frequency oscillations and are effected by other valves separated therefrom.

The circuit arrangement is preferably arranged in such manner that the direct current of the rectifier which is preceded by the greatest selectivity brings about the control.

In order that the invention may be clearly understood and readily carried into effect a circuit arrangement of this kind will be described hereinafter, by way of example, with reference to In the drawing:

Fig. 1 shows a circuit diagram of one form of the invention,

Fig. 2 graphically shows the operation of the invention, and

Fig. 3 shows a modified form of the invention.

In the circuit arrangement shown in Figure l the voltage of an intermediate frequency amplifier stage (not shown) of the receiving set is supplied through a condenser I to the control voltage drop across the resistance 13, which is also active in the second rectifier circuit, a current will not flow in the second rectifier circuit until the alternating voltage active across the circuit 9 has an amplitude which exceeds the value of the voltage across the resistance l3.

This action is illustrated in Figure 2 by means of a few curves. The curve (1. represents the voltage across the resistance l3 as a function of the frequency of the arriving signal. The point 6 corresponds to the resonance frequency of the circuit 4. The curve 1) represents the voltage across the circuit 9 as a function of the frequency. It is obvious that the rectifier I, II is not caused to become operative until this voltage exceeds the voltage across the resistance l3, consequently, when in tuning a frequency corresponding to one of the points 0 or d is reached. Not until then has the resistance [2 occurring through it a potential drop which applies such a bias to the tube [4 that the brake is set into operation. It is easy so to proportion the circuit 9 that the device is set into operation at a frequency which differs very little for example by a few hundred cycles, from the natural frequency of the circuit 9.

In the circuit arrangement described it is ensured that the action of the brake is practically independent of the intensity of the signal voltage and the adjustment is but slightly critical. The tube M can be connected so that the anode current increases upon the arrival of a signal. In this case, the second coil on the magnet core of the brake can be dispensed with. The control voltage for the braking device may also be derived from a further resistance, for example I2, since it can be obtained by adequate proportioning that the current of the rectifier path 6-1 ceases when the current across the second path attains a given value. Numerals iii and I9 denote appropriate I. F. bypass condensers.

Figure 3 shows a slightly different circuit arrangement which diifers from that shown in Figure 1 in that the valve 3 also serves as a braking valve. For this purpose the voltage active across the resistance I2 is led back to the control grid of this valve, and the braking device 15 is included in the anode circuit of this valve. Thus a saving of one tube is obtained. In this circuit arrangement it is desirable to provide a device that limits the voltage active in the output circuit of the valve 3. A glow discharge lamp 20 is provided for this purpose. The resistance 23 as well as the condenser 2i serve for smoothing the voltage led back. The resistance 22 is the input resistance for the grid of the valve 3.

What is claimed is:

1. In combination with the adjustable tuner element of a radio receiver, means to control adjustment of the tuner element, a control network for said means comprising a pair of rectifiers, a resonant signal input circuit, tuned to a desired signal frequency, coupled to one rectifier, a second signal input circuit, tuned to said desired frequency coupled to the second rectifier, the selectivity at the second circuit being greater, means for impressing signals on said signal circuits, means responsive to current flow in said one rectifier for preventing current flow in the second rectifier until the signal amplitude at the second input circuit attains a desired value, and means responsive to current flow in the second rectifier for controlling the operation of said first means.

2. In combination with the adjustable tuner element of a radio receiver, means to control adjustment of the tuner element, a control network for said means comprising a pair of rectifiers, a resonant signal input circuit, tuned to a desired signal frequency, coupled to one rectifier, a second signal input circuit, tuned to said desired frequency coupled to the second rectifier, the selectivity at the second circuit being greater, means for impressing signals on said signal circuits, means responsive to current flow in said one rectifier for preventing current flow in the second rectifier until the signal amplitude at the second input circuit attains a desired value, and means responsive to current flow in the second rectifier for controlling the operation of said first means, said tuner control means comprising a magnetic brake device constructed to prevent adjustment of the tuner element when energized.

3. In combination with the adjustable tuner element of a radio receiver, means to control adjustment of the tuner element, a control net- Work for said means comprising a pair of rectifiers, a resonant signal input circuit, tuned to a desired signal frequency, coupled to one rectifier, a second signal input circuit, tuned to said desired frequency coupled to the second rectifier, the selectivity at the second circuit being greater, means for impressing signals on said signal circuits, means responsive to current fiow in said one rectifier for preventing current flow in the second rectifier until the signal amplitude at the second input circuit attains a desired value, means responsive to current flow in the second rectifier for controlling the operation of said first means, said signal impressing means including an amplifier, and said amplifier also being included in said last named responsive means.

4. In combination with the adjustable tuner element of a radio receiver, means to control adju'stment of the tuner element, a control network for said means comprising a pair of rectifiers, a resonant signal input circuit, tuned to a desired signal frequency, coupled to one rectifier, a second signal input circuit, tuned to said desired frequency coupled to the second rectifier, the selectivity at the second circuit being greater, means for impressing signals on said signal circuits, means responsive to current flow in said one rectifier for preventing current flow in the second rectifier until the signal amplitude at the second input circuit attains a desired value, means responsive to current flow in the second rectifier for controlling the operation of said first means, said tuner control means comprising a magnetic brake device, and said controlling means including a tube in Whose space current circuit is connected said brake device.

5. In combination with the adjustable tuner element of a radio receiver, means to control adjustment of the tuner element, a control network for said means comprising a pair of rectifiers, a resonant signal input circuit, tuned to a desired signal frequency, coupled to one rectifier, a second signal input circuit, tuned to said desired frequency coupled to the second rectifier, the selectivity at the second circuit being greater, means for impressing signals on said signal circuits, means responsive to current fiow in said one rectifier for preventing current flow in the second rectifier until the signal amplitude at the second input circuit attains a desired value, means responsive to current flow in the second rectifier for controlling the operation of said first means, said signal impressing means and controlling means both including a common amplifier tube.

6. In combination with the adjustable tuner element of a radio receiver, means to control adjustment of the tuner element, a control network for said means comprising a pair of rectifiers, a resonant signal input circuit, tuned to a desired signal frequency, coupled to one rectifier, a second signal input circuit, tuned to said desired frequency coupled to the second rectifier, the selectivity at the second circuit being greater, means for impressing signals on said signal circuits, means responsive to current flow in said one rectifier for preventing current flow in the second rectifier until the signal amplitude at the second input circuit attains a desired value, means responsive to current flow in the second rectifier for controlling the operation of said first means, and a signal amplitude limiter connected across said first resonant input circuit.

'7. In combination with the adjustable tuner element of a radio receiver, means to control adjustment of the tuner element, a control network for said means comprising a pair of rectifiers, a resonant signal input circuit, tuned to a desired signal frequency, coupled to one rectifier, a second signal input circuit, tuned to said desired frequency coupled to the second rectifier, the selectivity at the second circuit being greater, means for impressing signals on said signal circuits, means responsive to current fiow in said one rectifier for preventing current flow in the second rectifier until the signal amplitude at the second input circuit attains a desired value, and means responsive to current flow in the second rectifier for controlling the operation of said first means, said tuner element having a metallic member operatively associated therewith, said adjustment control means including a device which acts as a magnet on said member when energized.

8. In combination with the adjustable tuner element of a radio receiver, means to control adjustment of the tuner element, a control network for said means comprising a pair of rectifiers, a resonant signal input circuit, tuned to a desired signal frequency, coupled to one rectifier, a second signal input circuit, tuned to said desired frequency coupled to the second rectifier, the selectivity at the second circuit being greater, means for impressing signals on said signal circuits, means responsive to current fiow in said one rectifier for preventing current flow in the second rectifier until the signal amplitude at the second input circuit attains a desired value, means responsive to current fiow in the second rectifier for controlling the operation of said first means, and each of said rectifiers being a diode, the diodes having a common cathode.

9. In combination with the adjustable station tuning element'of a superheterodyne receiver, an intermediate frequency energy network, a rectifier coupled thereto to rectify signal energy in said network, a second rectifier having an intermediate frequency input circuit which has a higher degree of selectivity than the first network, means for coupling the latter to said second rectifier input circuit, means responsive to current flow in the first rectifier for preventing rectification by the second rectifier until the signal amplitude at the input circuit thereof exceeds a predetermined amplitude, and means responsive to the rectified current output of the second rectifier for preventing adjustment of said tuning element.

10. In combination with the adjustable station tuning element of a superheterodyne receiver, an intermediate frequency energy network, a rectifier coupled thereto to rectify signal energy in said network, a second rectifier having an intermediate frequency input circuit which has a higher degree of selectivity than the first network, means for coupling the latter to said second rectifier input circuit, means responsive to current flow in the first rectifier for preventing rectification by the second rectifier until the signal amplitude at the input circuit thereof exceeds a predetermined amplitude, means responsive to the rectified current output of the second rectifier for preventing adjustment of said tuning element, an amplifier including said network in its space current circuit, and said amplifier being included in said last named means.

11. In combination with the adjustable station tuning element of a superheterodyne receiver, an intermediate frequency energy network, a rectifier coupled thereto to rectify signal energy in said network, a second rectifier having an intermediate frequency input circuit which has a higher degree of selectivity than the first network, means for coupling the latter to said second rectifier input circuit, means responsive to current fiow in the first rectifier for preventing rectification by the second rectifier until the signal amplitude at the input circuit thereof exceeds a predetermined amplitude, and means responsive to the rectified current output of the second rectifier for preventing adjustment of said tuning element, said last means including an electron discharge tube whose input electrodes are energized by the second rectifier current output.

CAREL JAN VAN LOON.