US2114154A - Receiver tuning indication circuits - Google Patents

Receiver tuning indication circuits Download PDF

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Publication number
US2114154A
US2114154A US78877A US7887736A US2114154A US 2114154 A US2114154 A US 2114154A US 78877 A US78877 A US 78877A US 7887736 A US7887736 A US 7887736A US 2114154 A US2114154 A US 2114154A
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United States
Prior art keywords
circuit
tube
indication
tuning
circuits
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Expired - Lifetime
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US78877A
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English (en)
Inventor
Steimel Karl
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Telefunken AG
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Telefunken AG
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Publication date
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Publication of US2114154A publication Critical patent/US2114154A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning
    • H03J3/02—Details
    • H03J3/12—Electrically-operated arrangements for indicating correct tuning
    • H03J3/14—Visual indication, e.g. magic eye

Definitions

  • This invention is concerned with a circuit. arrangement for receiving and amplifying means for electric communication and intelligence transmission, especially of the radio-frequency kind, in which the tuning of such circuits as are designed for receiving and conducting electrical oscillations, in reference to the frequency of such oscillations, is indicated and read by optical ways and means.
  • Optical indicator means of this sort have become extremely popular in modern receiver apparatus on the ground that by the aid thereof, say, in broadcast reception, the various adjacent transmitter stations are more readily located and the apparatus is more easily set thereto. Furthermore, when recourse is had to this principle, there is afforded the very desirable chance to reduce the receiver set in its gain or amplification while the tuning process is proceeding, and to restore the gain to such a value as is suitable for reproduction once the tuning process has been perfected and terminated.
  • this step which in the first place is intended for gain regulation, occasions also a reduction of the mean plate current in proportion to the change in the grid potential, and this may be utilized for tuning indication in a way similar to the method above suggested in connection with a grid-detector or audion circuit scheme.
  • This known scheme involves a number of drawbacks which are obviated by the present invention.
  • the suggestion is made, in addition to the above-described method of coarse or broad tuning indication to provide a fine or sharp tuning indication so that by the aid of the former process, ready location of the transmitter station, and by the latter, an exact setting to the carrier frequency is accomplishable.
  • coarse or broad indication recourse may be had to any one of such methods as have been disclosed in the earlier art, the more important ones of which have been discussed in the preamble.
  • This combined broad and sharp tuning indication is to be effected by that the differences in resonance properties of different oscillatory circuits are utilized in this manner that by the oscillation amplitude in one or more oscillatory circuits responsive to a comparatively broad resonance curve, a coarse or broad tuning indication is effected, while by the oscillation amplitude in at least one additional oscillation circuit with a narrower resonance curve fine tuning indication is accomplished.
  • coarse indication there could serve the change in the plate current of the radio-frequency amplifier stages of the set operating with automatic volume control, in that an ammeter is included in the plate current supply lead brought to the radio frequency tubes.
  • a tuning circuit subject to particularly low damping is coupled with a radiofrequency circuit of the receiver, the potential of the said low-damped circuit being impressed upon the grid of a tube operating with grid detection (audion).
  • the plate current decremental curve as a function of the tuning insures an extremely sharp and precise fine indication provided that the oscillation circuit has sufficiently low damping, in other words, a narrow-topped resonance characteristic. If necessary, for reducing the damping, recourse could be had also to artificial reduction of damping (de-attenuation) by means of regeneration.
  • Another means consists in the connection of two oscillation circuits coupled with each other in the manner of a band-pass filter, if the so-called crevasse between the two humps in the curve is used for fine indication.
  • One particularly advantageous embodiment of the basic idea of this invention consists in that for the simultaneous coarse and fine indication a single indicator means is used, the reading or indication of which is made a function. of the sum or the difierence of two resonance characteristics of dissimilar breadth.
  • the said indicator instrument could consist of any one of the known electric current (ammeter) instruments, more particularly of those equipped with two separate windings (one winding for fine indication current, and the other one for coarse indication current) or else glow-lamps, glow-tubes, or visual signal indicators.
  • Figs. 3-5 are graphs showing the operating characteristics of the circuits of Figs. 1 and 2.
  • A is an intermediate-frequency amplifier tube of the heterodyne receiver whose plate-current variation, as a function of the tuning, actuates and Works upon the indicator instrument m1 (coarse indication), while B is an additional, grid-detector, tube in which the variation of the plate current actuates the indicator instrument m2 (fine indication).
  • a and b denote an intermediate-frequency transformer which impresses the I. F. oscillations produced from the incoming oscillations upon the grid of the amplifier tube A.
  • the oscillations amplified by tube A become operative in circuit whence they are transferred to circuits (1 and 1.
  • the regulator potential is obtained by the aid of the diode D, and this voltage applied to the grid of the tube A occasions automatic volume control. Inasmuch as the said regulator potential becomes negative as the input amplitudes increase, it results in a reduction in the plate current of tube A with increase of input amplitude.
  • the ensuing sharpness of this regulation process in dependence upon thetuning is relatively small as a result of the use of oscillatory circuits having adequate band pass widths for the transmission of the sidebands.
  • the oscillations transferred to the circuit d cause a very abrupt decrease of the plate current of B, upon setting the apparatus to the carrier wave, particularly as a result of the feedback by the aid of e.
  • Instrument m2 similarly serves for fine indication.
  • the tube B functions as the source of current for meter m2; it does not affect the signal in its passage through the receiver.
  • the audio signal may be derived from the I. F. energy in any well known manner.
  • Fig. 2 shows another improvement of the above described circuit schemes. Coarse and fine indication in this arrangement is effected-simultaneously by one and the same indicator device m in which are operative the sum total of the two plate current variations of the tubes A and C.
  • Figs. 3 and 4 show graphically the indications as a function. of the tuning as a result of summation or integrating action.
  • ma is the curve of the plate-current change for tube A, while me is the corresponding curve for tube C.
  • Fig. 2 comprises another idea and object of this invention.
  • the same resides in the double utilization of the additional tube C included in the circuit arrangement for the purpose of sharp indication.
  • the idea is to use the change in plate current serving for fine indication, with high selectance, at the same time for the production of a regulator Voltage, with a view to rendering the amplification of the set operative only upon the proper tuning positions having been ascertained.
  • Circuit organizations designed to insure mute tuning are fundamentally known in the prior art. What is here disclosed is a particularly efficient and useful double utilization of tube C for simultaneous fine indication and mute tun-
  • the gain of I. F. amplifier A is regulated by diode D as explained in Fig. 1; the tuned circuit g being coupled to circuit 0.
  • the tube B has its plate and cathode connected through tuned circuit d and load resistor I; thus providing a diode detector circuit.
  • the audio signal is taken 01f at NF.
  • the tube C has its input circuit e coupled to circuit 0; the plate of tube C being regeneratively coupled to the circuit e by coil 1.
  • the resistor R is connected between the plate and cathode of tube C; the voltage drop across it is a maximum when no signals are received since network 2 in the input circuit of tube C renders it a grid rectification detector.
  • the grid 3 of tube B is connected to a point on resistor R by lead 4; and the grid 3 will be biased highly negative when no signals are received.
  • the diode detection action of tube B is prevented, and the receiver rendered quiet, when the grid 3 is biased highly negative.
  • the meter m is in the plate circuits of tubes A and C.
  • the circuit e is so loosely coupled to circuit 0 as to produce a narrow resonance curve.
  • the resonance curve will be made still sharper. Since the slope of the characteristic of detector B depends on the bias of grid 3, the detector efficiency can be varied through variation of the bias of grid 3.
  • the coupling between circuits 0 and g is relatively broad.
  • a signal transmission tube having signal input and output circuits, a rectifier having a signal input circuit coupled to said output circuit to provide a relatively broad resonance curve characteristic, means responsive to an increase of rectifier current output, for decreasing the tube gain, a space current device having input electrodes, a resonant network coupling said input electrodes to said output circuit to provide a relatively sharper resonance curve characteristic than said first characteristic, and current indicator means, responsive to the space current flow of said device, for indicating substantially exact resonance between said tube input circuit and signals impressed thereon, said indicator means being additionally responsive to the space current flow of said transmission tube.
  • a signal transmission tube having signal input and output circuits, a rectifier having a signal input circuit coupled to said output circuit to provide a relatively broad resonance curve characteristic, means responsive to an increase of rectifier current output, for decreasing the tube gain, a space current device having input electrodes, a resonant network other than said rectifier input circuit coupling said input electrodes to said output circuit to provide a relatively sharper resonance curve characteristic than said first characteristic, and current indicator means, responsive to the space current flow of said device, for indicating substantially exact resonance between said tube input circuit and signals impressed thereon, and means for reducing the damping of the said resonant network thereby to further sharpen said second characteristic, said indicator means being additionally responsive to the space current flow of said transmission tube.
  • a signal transmission tube having signal input and output circuits, a rectifier having a signal input circuit coupled to said output circuit to provide a relatively broad resonance curve characteristic, means responsive to an increase of rectifier current output, for decreasing the tube gain, a space current device having input electrodes, a resonant network coupling said input electrodes to said output circuit to provide a relatively sharper resonance curve characteristic than said first characteristic, current indicator means, responsive to the space current flow of said device, for indicating substantially exact resonance between said tube input circuit and signals impressed thereon, and means responsive to a change in space current flow of said device due to absence of signals, for preventing signal transmission through said system, said indicator means being additionally responsive to the space current flow of said transmission tube.
  • a signal transmission tube having signal input and output circuits, a rectifier having a signal input circuit coupled to said output circuit to provide a relatively broad resonance curve characteristic, means responsive to an increase of rectifier current output, for decreasing the tube gain, a space current device having input electrodes, a resonant network coupling said input electrodes to said output circuit to provide a relatively sharper resonance curve characteristic than said first characteristic, current indicator means, responsive to the space current flow of said device, for indicating substantially exact resonance between said tube input circuit and signals impressed thereon, a detector tube having input electrodes coupled to the transmission tube output circuit, and means, responsive to a predetermined change in space current of said device due to absence of received signals, for rendering the detector tube ineificient, said indicator means being additionally responsive to the space current flow of said transmission tube.

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US78877A 1935-05-08 1936-05-09 Receiver tuning indication circuits Expired - Lifetime US2114154A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2114154X 1935-05-08

Publications (1)

Publication Number Publication Date
US2114154A true US2114154A (en) 1938-04-12

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US78877A Expired - Lifetime US2114154A (en) 1935-05-08 1936-05-09 Receiver tuning indication circuits

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US (1) US2114154A (fr)
ES (1) ES142202A1 (fr)
FR (1) FR805227A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3249872A (en) * 1962-01-13 1966-05-03 Philips Corp Circuit for tuning indication in a receiver for am/fm-reception
US5164729A (en) * 1990-10-05 1992-11-17 Cincinnati Microwave, Inc. Police radar warning receiver with auto-mute function

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3249872A (en) * 1962-01-13 1966-05-03 Philips Corp Circuit for tuning indication in a receiver for am/fm-reception
US5164729A (en) * 1990-10-05 1992-11-17 Cincinnati Microwave, Inc. Police radar warning receiver with auto-mute function

Also Published As

Publication number Publication date
ES142202A1 (es) 1936-07-16
FR805227A (fr) 1936-11-14

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