US3761823A - Automotive radio rundown noise eliminator - Google Patents

Automotive radio rundown noise eliminator Download PDF

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Publication number
US3761823A
US3761823A US00166516A US3761823DA US3761823A US 3761823 A US3761823 A US 3761823A US 00166516 A US00166516 A US 00166516A US 3761823D A US3761823D A US 3761823DA US 3761823 A US3761823 A US 3761823A
Authority
US
United States
Prior art keywords
receiver
voltage
radio
rundown
power supply
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
US00166516A
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English (en)
Inventor
W Harris
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.)
Space Systems Loral LLC
Ford Motor Co
Original Assignee
Philco Ford 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 Philco Ford Corp filed Critical Philco Ford Corp
Application granted granted Critical
Publication of US3761823A publication Critical patent/US3761823A/en
Assigned to FORD MOTOR COMPANY, A CORP. OF DE reassignment FORD MOTOR COMPANY, A CORP. OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: FORD AEROSPACE CORPORATION
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning
    • H03J3/02—Details
    • H03J3/16—Tuning without displacement of reactive element, e.g. by varying permeability
    • H03J3/18—Tuning without displacement of reactive element, e.g. by varying permeability by discharge tube or semiconductor device simulating variable reactance
    • H03J3/185—Tuning without displacement of reactive element, e.g. by varying permeability by discharge tube or semiconductor device simulating variable reactance with varactors, i.e. voltage variable reactive diodes

Definitions

  • the rundown noise problem is particularly aggravated in radio receivers employing circuits designed to have voltage tracking. Such circuits are arranged so that bias voltages follow changes in Supply voltages to provide for correct operation over a wide range of'supply voltage. Such circuits will operate at supply voltages of quite low value, and, while this is desirable from a receiver operation standpoint, the rundown interval is extended and the associated noise more evident.
  • an automatic switch that is designed to sense the reduction in voltage that accompanies rundown and to switch the radio offimmediately.
  • This can be achieved by a simple electrical relay or its electronic latch equivalent.
  • the switching action can be incorporated into circuits already present in the radio.
  • FIG. 1 is a partial schematic block diagram of an automobile radio employing voltage variable capacitors tuning, and the power supply system, showing one embodiment of the invention.
  • FIG. 2 shows a second embodiment of the invention.
  • FIG. 1 shows the automobile elements of interest in relation to a prior art radio switching system, and one means for practicing the invention is shown connected between points A and B. Normally the battery 1 supplies current through the ignition switch 2 in its on position to both the radio 3 and the electricmotor-containing accessory 4.
  • the radio being considered is of the FM-AM variety.
  • the AM portion 5 of the radio is conventional and employs permeability tuning
  • the FM portion 6 employs electronic tuning with voltage variable capacitor elements providing the variable function of tuned circuits 7.
  • a source of variable voltage 8 is used to provide the tuning voltage for the VVCs.
  • the switching system uses a SPST switch 9 with an electronic circuit in place of the typical SPDT switch in the battery line.
  • the circuit shown which is claimed in a copending application Ser. No. 169,658 Filed Aug. 6, 1971, is preferred because the SPST switch is more reliable than a SPDT switch and, due to the transistor, the switch passes very little current thereby prolonging its life.
  • the circuit operates as follows.
  • the PNP transistor 10 When the FM-AM switch 9 is in the FM position as shown, the PNP transistor 10 is biased to conduct and the FM and electronic tuning circuits 6 and 8 are energized.
  • the germanium diode 11 is forward biased thereby lowering the voltage applied to the AM circuits to about 0.3 volt, a level too low for AM circuit operation.
  • Resistor 12 provides the required voltage dropping action.
  • transistor 10 When switch 9 is open, or in the AM position, transistor 10 is biased nonconductive, thereby removing power from the FM circuits. Diode 11 is no longer conductive and'the AM circuits 5 are powered through resistor 12. Resistor 13 and capacitor 14 act as a power line filter. Resistor l5 limits the base current in transistor 10.
  • relay 18 In the prior art circuit, relay 18 would be omitted and points A and B connected together.
  • voltage sensitive relay 18 has its coil connected across the receiver power line, and the relay contacts are connected in series with the radio circuit.
  • Relay 18 is adjusted to pull in at about 11 volts, the lowest expected battery voltage.
  • Relay 18 is adjusted to drop out at about ,7 to 8 volts, the maximum line voltage value maintained by the coasting electric motor 17.
  • diode 19 is a 7.5 volt silicon zener diode such as type 1N958B.
  • diode 19 will provide base current to the transistor under normal conditions to keep it conducting.
  • the ignition switch 2 is turned off, the emitter of the transistor will drop to about 7.5 volts under which condition zener diode 19 can no longer supply base current. With zener diode open,transistor 10 will no longer conduct and the FM circuits are turned off.
  • the transistor emitter In general with a 7.5 volt zener diode, the transistor emitter must be in excess of about 8.2 volts for the FM circuits to operate. When the line voltage drops to the 7-8 volt level at the start of rundown, the circuit will act to terminate radio operation.
  • the invention can be applied to any electronically tuned receiver that has the declining voltage characteristic.
  • the circuits could be incorporated into the d-c supply of a solid state receiver having large filter capacitors.
  • the receiver circuits at :least the electronic tuning circuits, are disconnected from the filter capacitors.
  • the rundown noise that would ordinarily be associated with shutting the receiver off is avoided.
  • two forms of switching have been shown, other equivalent circuits could be employed. The invention should be limited only by the following claims.
  • switching means connected in series with the voltage supply terminals of said receiver so as to terminate operation of said receiver upon actuation of said switching means and responsive to the decline of said supply voltage to a predetermined level for termination by actuation of said switch means the op eration of said receiver when said voltage falls to said level.
  • said switching means comprises an electrical relay adjusted to drop out at said predetermined level.
  • said switching means comprises an electronic switch having a zener diode to establish switching at said predetermined level.
  • a radio receiver adapted to be connected to a source of voltage which source, when deenergized, continues to supply voltage to said radio receiver at a declining rate for a brief period after deenergization, said receiver employing voltage variable capacitors to effect tuning of said receiver in response to a voltage whose magnitude is a function of the voltage of said source, said voltage variable capacitors producing an undesirable noise in said receiver as they sweep the tuning of said receiver in response to said supply voltage decline, the improvement comprising switching means connected in series between said source and said radio receiver, and responsive to a decline in voltage of said source to a predetermined value, for terminating automatically the operation of said radio receiver.
  • an automobile radio receiver having terminals adapted to be connected to the electrical system of an automobile, said automobile having, in addition to the conventional battery power supply system, accessories that act as sources of declining potential when disconnected from said battery power supply, said receiver employing a plurality of voltage variable capacitors to effect electronic tuning of said receiver in response to a voltage whose magnitude is a function of the voltage applied to said terminals, said voltage variable capacitors producing an undesirable noise in said receiver when subjected to said declining potential, the improvement comprising switching means connected in series between said terminals and said radio receiver circuits, and responsive to the application of substantially less than normal voltage to said terminals, for terminating automatically operation of said radio receiver.

Landscapes

  • Noise Elimination (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Channel Selection Circuits, Automatic Tuning Circuits (AREA)
  • Circuits Of Receivers In General (AREA)
US00166516A 1971-07-27 1971-07-27 Automotive radio rundown noise eliminator Expired - Lifetime US3761823A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US16651671A 1971-07-27 1971-07-27

Publications (1)

Publication Number Publication Date
US3761823A true US3761823A (en) 1973-09-25

Family

ID=22603646

Family Applications (1)

Application Number Title Priority Date Filing Date
US00166516A Expired - Lifetime US3761823A (en) 1971-07-27 1971-07-27 Automotive radio rundown noise eliminator

Country Status (8)

Country Link
US (1) US3761823A (pt)
JP (1) JPS5512775B1 (pt)
AR (1) AR193882A1 (pt)
BR (1) BR7204968D0 (pt)
CA (1) CA954591A (pt)
DE (1) DE2236713A1 (pt)
GB (1) GB1373724A (pt)
IT (1) IT961719B (pt)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4063175A (en) * 1976-08-05 1977-12-13 Friedman Eliot I Amplifier for receive mode operation
US4065723A (en) * 1976-08-16 1977-12-27 General Motors Corporation Tuned radio frequency amplifier with back to back varactor diodes connected through a common cathode lead
US4673832A (en) * 1985-03-13 1987-06-16 Aisin Seiki Kabushiki Kaisha Safety device for electronic equipments
US4721985A (en) * 1984-07-03 1988-01-26 Thomson-Csf Variable capacitance element controllable by a D.C. voltage

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2324424A (en) * 1939-10-28 1943-07-13 Pollack Paul Battery protection and indicating system
US2617019A (en) * 1946-07-17 1952-11-04 Hartford Nat Bank & Trust Co Silencing network
US2678391A (en) * 1952-07-02 1954-05-11 Rca Corp Protective circuit
US3189830A (en) * 1961-05-08 1965-06-15 Gen Motors Corp Automatic frequency control with compensation for variable supply voltage
US3440544A (en) * 1966-11-01 1969-04-22 Motorola Inc Manual,automatic,and semiautomatic tuning circuits utilizing voltage variable capacitance diodes
US3445746A (en) * 1966-11-10 1969-05-20 Camco Inc Battery low voltage cutoff and regulator
US3521204A (en) * 1969-01-03 1970-07-21 Motorola Inc Electronically tuned pushbutton radio having station selecting comparison means
US3588856A (en) * 1968-07-17 1971-06-28 Gen Electric Failure warning system

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2324424A (en) * 1939-10-28 1943-07-13 Pollack Paul Battery protection and indicating system
US2617019A (en) * 1946-07-17 1952-11-04 Hartford Nat Bank & Trust Co Silencing network
US2678391A (en) * 1952-07-02 1954-05-11 Rca Corp Protective circuit
US3189830A (en) * 1961-05-08 1965-06-15 Gen Motors Corp Automatic frequency control with compensation for variable supply voltage
US3440544A (en) * 1966-11-01 1969-04-22 Motorola Inc Manual,automatic,and semiautomatic tuning circuits utilizing voltage variable capacitance diodes
US3445746A (en) * 1966-11-10 1969-05-20 Camco Inc Battery low voltage cutoff and regulator
US3588856A (en) * 1968-07-17 1971-06-28 Gen Electric Failure warning system
US3521204A (en) * 1969-01-03 1970-07-21 Motorola Inc Electronically tuned pushbutton radio having station selecting comparison means

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4063175A (en) * 1976-08-05 1977-12-13 Friedman Eliot I Amplifier for receive mode operation
US4065723A (en) * 1976-08-16 1977-12-27 General Motors Corporation Tuned radio frequency amplifier with back to back varactor diodes connected through a common cathode lead
US4721985A (en) * 1984-07-03 1988-01-26 Thomson-Csf Variable capacitance element controllable by a D.C. voltage
US4673832A (en) * 1985-03-13 1987-06-16 Aisin Seiki Kabushiki Kaisha Safety device for electronic equipments

Also Published As

Publication number Publication date
IT961719B (it) 1973-12-10
BR7204968D0 (pt) 1973-05-10
DE2236713A1 (de) 1973-02-15
CA954591A (en) 1974-09-10
GB1373724A (en) 1974-11-13
JPS5512775B1 (pt) 1980-04-04
AR193882A1 (es) 1973-05-31

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Legal Events

Date Code Title Description
AS Assignment

Owner name: FORD MOTOR COMPANY, A CORP. OF DE, DELAWARE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:FORD AEROSPACE CORPORATION;REEL/FRAME:005377/0188

Effective date: 19900612