US2189050A - Tuning circuits - Google Patents

Tuning circuits Download PDF

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Publication number
US2189050A
US2189050A US169100A US16910037A US2189050A US 2189050 A US2189050 A US 2189050A US 169100 A US169100 A US 169100A US 16910037 A US16910037 A US 16910037A US 2189050 A US2189050 A US 2189050A
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US
United States
Prior art keywords
tuning
voltage
circuit
relay
receiver
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US169100A
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English (en)
Inventor
Carel Jan Van Loon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RCA Corp
Original Assignee
RCA Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by RCA Corp filed Critical RCA Corp
Application granted granted Critical
Publication of US2189050A publication Critical patent/US2189050A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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

Definitions

  • the invention relates to a circuit-arrangement for facilitatingthe tuning of a radio-receiving apparatus by means of a device which operates when the receiver is' correctly tuned. Such devices are'particularly important in superheterodyne receiving apparatus with which it is often.
  • Such a tuning-facilitating device must, of course, be preceded by ;-selec,tive controlling means comprising, for example, tuning circuits, which meansensure that the device can. only operate in a comparatively narrow. band .-of fre'- quencies. It, has previously been proposed to rectify the output vloltage. of these selective means so that a direct current voltage is obtained which was utilized for controlling the tuning facilitating device, the] circuit arrangement being such that the width of the band of frequencies within which said control voltage occurredpwas substantially independent of the signal amplitude.
  • the control of the said device is efiectedby an auxiliary alternatingvoltage of comparatively .low frequency which is combined. with the high 'or] intermediatefrequency. signals in such manner that it can only have effect in a comparatively narrow band of frequencies in the neighborhood of the correct tuning, an extremely simple andreliable control being thus obtained.
  • a further advantage is that for the amplification of the control voltage use may be made of an alternating current amplifier. As appears from the following it is, possible to utilize as such the amplifiers intended for the, amplification of the signal voltages.
  • the auxiliary alternating voltage should preferably be taken -fro 1 n the power mains.
  • Fig. l is a block diagram of acircuit embodying one form of the invention
  • Fig. 2 discloses .a modified form of circuit shown in greater detail
  • Figl 3' shows a modification of. a portion of the circuit shown in Fig 2.
  • the block 9 denotes a high-frequency amplifier, 2 a local oscillator and 3 an intermediate-frequency amplifier.
  • the interm'ediatefrequency oscillations amplified are demodulated in a device 4.
  • the low-frequency "oscillations produced are supplied, if desired after.
  • the tuning facilitating device For the actuation of the tuning facilitating deviceis used 'a side-channeliwhich is connected, at a suitable point to the intermediate-frequency amplifier.
  • a side-channel for controllin'g'purposes, is known in itself. .With the known circuit arrangements the oscillations are .led through a selective devicewhich only passes avery narrow band of frequencies; the output energy is-rectified and controlsa relay .by which the brake, or ,the'optical indicating device, is
  • the intermediate- 20 frequency oscillations are modulated in a device 5 with an auxiliary alternating voltage which maybe, taken,-'for example, through a trans formeri from the power mains.;
  • the oscillations thus modulated are subsequently passed through a selective device 8 which transmits a narrow band of frequencies, whereupon the energy. transmitted is demodulated in 9 and, if de-' sired,' is furtheramplified.
  • a selective device 8 which transmits a narrow band of frequencies, whereupon the energy. transmitted is demodulated in 9 and, if de-' sired,' is furtheramplified.
  • an alternating current relay m which is consequently put into operation when correct tuning is obtained. It is ofv course the relay',in which event use may be made of a direct current relay.
  • the relay may be formed as a brake or may actuate a braking device.
  • the control voltage may be introduced into the. high-frequency portion I, or the. intermediatefrequency amplifier 3. In this case it is 'neces- ,sary, or at least desirable, to cause this voltage to disappear again after correct tuning has been attained.
  • a slidable tap On the resistance H is a slidable tap which is This device comprises a switch 23 which occupies
  • the tap on v the resistance l? is connected to the said grid through the condenser 24.
  • another low-frequency amplifying tube 26 the anode circuit of which includes an output transformer 2'! whose secondary winding supplies a loudspeaker 28.
  • the relay 35 may be formed as a brake which acts, when correct tuning is attained, on a brake disc 32 with the result that furtherturning of a tuning knob 3
  • a switch i l-and a source of voltage 38 which furnishes a voltage of low frequency, e. g., of 50 cycles per second.
  • output circuit further comprises a switch 33' by means of which therelay 36 may be changed over to the secondary winding of a. transformer 40.
  • the primary winding of this transformer? is connected to the alternating current supply.
  • the relaytfi is formed as an alternating current relay.
  • the switches 22, 23, 25),33 and 3! are mutually coupledas indicated by the dot andda'shlines. When the brake responds they are simultaneously actuated.
  • the circuit arrangement shown acts; as follows:
  • the intermediate-frequencyoscillations are: i modulated with a' frequency of;50 cycles per sec-, end. However, when thereis no tuning this frequency cannot reach the grid of the tube 25 since in this case a voltage is not yet set up across thefl o resistance An alternating voltage component of 50 cycles per second does not occur across the i v resistance 20 until the circuit I9 rectifies; that is to'sayuntil correct tuning. is 'obtained.
  • This y component is amplified by the low-frequency am- 15 I plifying tubes and 2B, andcauses the relay 3!] included in the output circuit -to respond with the result that any further rotation of the knob 3
  • the v relay has to be set again. out of operation.
  • thatendthe tuning knob may be'associated with a switch device which is actuated, for example by a longitudinal motion of the knob or by rotation Y of the'latter through a determined angle, for example, against the actionof a spring.
  • a system for determining accurate tuning I of a radio receiver comp-rising a braking device -operatively related to the tuning. mechanism of the receiver and preventing further adjustment of the tuning mechanism when in accurately tuned position, a relay for actuating the braking device, a locally produced auxiliary source of low frequency voltage superimposed on the receiver circuit for energizing the relay, and means included in said circuit for blocking transmission of said auxiliary voltage to the relayexcept ref Also in this .case an alternating;
  • circuit means permitting transmission of said auxiliary voltage to the relay only when the receiver is in accurately tuned condition.
  • the signal detector for preventing the transmisa low-frequency portion and a sound reproducer, of means for facilitating accurate tuning of the receiver and preventing further adjustment of the receiver tuning mechanism when in accurate tuning position, comprising a braking device operatively related to the tuning mechanism a relay associated withthe low frequency portion of the to the tuning mechanism of the receiver and imposed on the high frequency portion of the receiver for energizing the relay, circuit, means operating in conjunction with the signal detector permitting transmission of said auxiliary voltage to the relay only when the tuned circuits of the receiver are so adjusted to pass a comparatively narrow band offrequencies in the neighborhood of correct tuning, and means controlled by the relay in its operative condition to discon-- nect theau'xiliary source of voltage and to connect the signal detector directly to the low fre- .quency portion of the receiver.
  • a signal channel comprising a high. frequency amplifier portion, a detector and a low frequency amplifier portion, means for adjusting the tuning of the receiver, a brake member associated with said tuning means and operative only when the receiving circuit is in accurately tuned condition, and means for controlling the operation of said brake member comprising a'locally produced source of low frequency voltage, and circuit means associated with the detector for preventing the transmission of the low frequency voltage when the receiving circuit issusbtantially off" tune.

Landscapes

  • Channel Selection Circuits, Automatic Tuning Circuits (AREA)
  • Amplifiers (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
US169100A 1936-11-02 1937-10-15 Tuning circuits Expired - Lifetime US2189050A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE203818X 1936-11-02

Publications (1)

Publication Number Publication Date
US2189050A true US2189050A (en) 1940-02-06

Family

ID=5778561

Family Applications (1)

Application Number Title Priority Date Filing Date
US169100A Expired - Lifetime US2189050A (en) 1936-11-02 1937-10-15 Tuning circuits

Country Status (8)

Country Link
US (1) US2189050A (en))
AT (1) AT157218B (en))
BE (1) BE424409A (en))
CH (1) CH203818A (en))
DK (1) DK56624C (en))
FR (1) FR828591A (en))
GB (1) GB490272A (en))
NL (1) NL54628C (en))

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2571309A (en) * 1946-02-26 1951-10-16 Philco Corp Tuning aid for frequency- modulation receivers

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2571309A (en) * 1946-02-26 1951-10-16 Philco Corp Tuning aid for frequency- modulation receivers

Also Published As

Publication number Publication date
NL54628C (en))
AT157218B (de) 1939-10-10
FR828591A (fr) 1938-05-20
BE424409A (en))
GB490272A (en) 1938-08-11
CH203818A (de) 1939-03-31
DK56624C (da) 1939-09-04

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