US2377475A - Tuning arrangement in radio receivers - Google Patents

Tuning arrangement in radio receivers Download PDF

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Publication number
US2377475A
US2377475A US488837A US48883743A US2377475A US 2377475 A US2377475 A US 2377475A US 488837 A US488837 A US 488837A US 48883743 A US48883743 A US 48883743A US 2377475 A US2377475 A US 2377475A
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US
United States
Prior art keywords
resistance
valve
thermistor
circuit
plate
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
US488837A
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English (en)
Inventor
Ambrose Dermot Min
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.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
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 Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Application granted granted Critical
Publication of US2377475A publication Critical patent/US2377475A/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
    • H03J3/14—Visual indication, e.g. magic eye

Definitions

  • present invention relates to improvements ticularly suitable' for a variety of special applications in electric circuits
  • a resistance material having a high negative temperature coefiicient of resistance comprises'a mixture of manganese oxide and nickel oxide, with or without the addition of certain other metallic oxides, themixture-being suitably heat treated.
  • Thermistors have been employed in two diiierent'forms: (a) known as a Directly Heated Therm'is'tor' and comprising a resistance element of the-thermally sensitive resistance material pro vided with'suitable lead-out conductors or terminals; and" (b) known as an Indirectly Heated Therm-istor'comprising the element (a) provided in addition with a heating-coil electrically insulated from'the element.
  • a directly heated thermistor is primarily intended to be controlled by the current which flows throgh varies-the temperature andalso the resistance accordingly.
  • Such a thermistor will also be affected by the temperature of .its surroundings and may'therefore be used for thermostatic control and like' purposes with or without direct heating by the current flowing, through it.
  • An indirectly heatedthermistor is chiefly designed to'be heated by-acontrolling current which flows through the heating coil and which will usually;but not necessarily, be'difl'erent'from'the current which flows th'roughthe resistance element, but this type of thermistor. may also be subjected to either or both of the'types'of control applicable to a directly heatedthermistor'.
  • a tuning indicating arrangement fora radio receiver provided with automatic volume control, comprising an indirectly heated ther mistor having its heating coil connected in series with the plate circuit of a thermionic valve in the receiver; the plate current of which valve is varied by the operation of the volume control, the resistance elementof the thermistor being connected in a local "circuit with a tuning indicator and adapted to control the indicator in accord ance with the changes in the tuning adjustmentof the receiver.
  • Fig. 1 shows a schematic circuit diagram of one embodiment of the invention.
  • valve V is shown as'an intermediate frequency" amplifying valve in a radio receiver, for example.
  • Incoming signals are applied to the control grid circuit from terminals 1 and'2' and after amplification are deliveredto the next'stage (not shown) through the output mtransformer OT and terminals 3 and 4.
  • transformer has its primary winding connected in series with the plate circuit of the valve and the primary and secondary windings are tuned by'mean's of the condensers Cs and Cs respectively.
  • the cathodeof' the valve is suitably, biased by 7 means ofthe series resistanceRz with the usual by- 1 passcondenser Ct and a negative voltage derived froman automatic volume control arrangement (not shown) of any welhknown type is applied through terminal '5 to an auxiliary grid of the valve' V."
  • a blocking condenser C1 completes the circuit for alternating currents.
  • the positive terminal of the high tension supply for the plate of the valve V is connected from terminaLG through'the heating coil r of an indirectly heated.
  • thermistor'T whose-resistanceelement R is connected in parallel with an incandescent electric lamp L which is lighted from a suitable constant voltage source S connected to the terminals I and 8, in series with a constant resistance R1.
  • the source S may supply either alternating or direct current, and might be the same as one of the power supplies for the valve V or other valves of the receiving set.
  • the thermistor has a negative temperature coefficient of resist-* ance, so that it has a low resistance when the current through the heating coil r is large.
  • the incoming signals at terminals I and 2 will be of very low level, and the automatic volumefcontrol negative voltage at terminal 5 will be small.
  • the plate current of the valve V will accordingly be large, the thermistor resistance R will be low, and the lamp L will accordingly be heavily shunted and will glow only faintly, if at all;
  • thermistor with a positive temperature coefficient of resistance may also be used. This will give minimum brightness when the circuit is properly tuned in the arrange-' ment of Fig. 1, and maximum brightness in the series with the resistance R.
  • the thermistor T may also be arranged to control a neon tube indicatorin the manner shown in. Fig. 2.
  • This figure shows the modification of that part of Fig. 1 which is below and to-the right-hand side of terminal A; everything above and to the left-hand side of A is the same.
  • N is a neon tube indicator or otherlike gas discharge device having a cathode H or relatively large area, a small control electrode, and a alternative arrangement when the lamp L isyin terminal to the positive high tension terminal 6 through a resistance R3.
  • This other terminal of the resistance R is also connected through a resistance R4 to the control electrode I! of the neon tube.
  • the resistance R will be a maximum when the receiver is in tune, the plate current of the valve V-in Fig.1 being a minimum under this condition.
  • This will raise the control electrode l2 of the neon tube N (Fig. 2) to a maximum positive potential, and will in turn cause the glow in the tube N to be of maximum brightness and to cover a maximum area on the cathode II.
  • the control electrode I2 When the receiver is untuned, the control electrode I2 will be at a low potential and there will be little or no glow.
  • a thermistor with a positive temperature 00- efficient of resistance will produce a substantially similar'effect if R and R3 are interchanged in Fig. 2.
  • the resistance R will be a minimum when the receiver is in tune so that it will cause the control electrode l2 to assume a maximum positive potential as before.
  • the sensitivity of the indicators can be made the signal greaterthan if the thermistor were not used.
  • a radio receiver having an amplifying valve including a plate circuitthe-plate current of which valve is variedbythe level of signals entering said vane; a tuning indicating devicecom, prising. a thermistor having a thermally sensitive resistance element and a heating coil;electrically insulated .from'. said element, a series connection from s'aidcoil to said plate circuit a. local circuit connected to said resistanc element and a tuning indicator in said local circuit connected to SaidIesistanceeIernent, wherebysaid resistance element is adapted to control said indicator in accordance with the changes in the tuning adjustment of the radio receiver, and whereby no transfer of electricalenergy between said plate circuit and said indicator takes place.
  • a tuning indicating device comprising a thermistor having a thermally sensitive, resistance element and cheating coil electrically' insulated from said element, a series conmotion from said coil to saidplate circuit, a local circuit. connected to said resistance element, an
  • incandescent lamp in said local circuit connected to said resistance element and a source of electromotiveforcefor supplying current to said lamp, whereby. ⁇ said resistance element controls said incandescent. lamp in accordance with the changes in the tuning adjustment of the radio receiver, and whereby no transfer of electrical energyfbetween said plate le? tim iece. a H
  • a radio receiver having an amplifying valve including a plate circuit the plate current of which valve is varied by signals entering said valve, a, tuning indicating device comprising a thermistor having a thermally sensitive resistance.
  • a radio receiver having an amplifying valve including a plate circuit the plate current of which valve is varied by signals entering said valve, a, tuning indicating device comprising a thermistor having a thermally sensitive resistance element and a heating coil electrically insulated from said element, a series connection from said coil to said plate circuit, a local circuit connected to said resistance element, a gas-discharge tube in said local circuit connected to said resistance element and a source of electromotive force for supplying current to said gas-discharge tube, whereby no transfer of electrical energy between said plate circuit and said indicator takes place.
  • a tuning indicating device comprising a thermistor having a thermally sensitive resistance element and a heating coil electrically insulated from said element, a series connection from said coil to said plate circuit, a local circuit, a gas-discharge tube in said local circuit, said gas-discharge tube comprising a cathode, an anode and a control electrode, a source of constant voltage connected to supply said tube, a constant resistance across said source and to which said resistance element is connected in series, a connection from said control element to the junction point of said resistance element and said constant resistance, and a second constant resistance in series with said last named connection, whereby no transfer of electrical energy between said plate circuit and said indicator takes place.

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US488837A 1942-06-05 1943-05-28 Tuning arrangement in radio receivers Expired - Lifetime US2377475A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB257893X 1942-06-05

Publications (1)

Publication Number Publication Date
US2377475A true US2377475A (en) 1945-06-05

Family

ID=10233326

Family Applications (1)

Application Number Title Priority Date Filing Date
US488837A Expired - Lifetime US2377475A (en) 1942-06-05 1943-05-28 Tuning arrangement in radio receivers

Country Status (4)

Country Link
US (1) US2377475A (el)
BE (1) BE463816A (el)
CH (1) CH257893A (el)
FR (1) FR924977A (el)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2992363A (en) * 1955-06-03 1961-07-11 Gasaccumulator Svenska Ab Stand-by unit arrangement

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2992363A (en) * 1955-06-03 1961-07-11 Gasaccumulator Svenska Ab Stand-by unit arrangement

Also Published As

Publication number Publication date
CH257893A (fr) 1948-10-31
FR924977A (fr) 1947-08-21
BE463816A (el)

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