US3889193A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic frequency control circuit
Assignee: Sony Corp
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Filing: 1974-01-16
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Granted: 1975-06-10
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Expires: 1994-01-16
Abstract
Abstract An automatic frequency control circuit having a defeating circuit for defeating an automatic frequency controlling operation of a receiver having an electronic tuning circuit for a predetermined time period after a power switch for the receiver is turned on.
Inventors
- 👤 Tadao Sasaki
- 👤 Yasuji Kato
- 👤 Toshiaki Meguro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:04
CPC Classifications
H; H03; H03J; H03J7/00; H03J7/02; H03J7/023
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
289 words
An automatic frequency control circuit for tuning apparatus, the tuning apparatus having an electronically variable frequency generating means, and the automatic frequency control circuit being responsive to the output produced by a frequency discriminator supplied with IF signals, comprising: a variable capacitance diode coupled to said variable frequency generating means, the frequency generated by said variable frequency generating means being a function of the capacitance value; a differential output DC amplifier connected to said frequency discriminator and having first and second output terminals across which said variable capacitance diode is coupled, said differential output DC amplifier providing first and second voltages at said first and second output terminals, respectively, having substantially the same magnitude and opposite polarity in accordance with the frequency of the IF signals, said variable capacitance diode exhibiting a capacitance value determined by the difference between said first and second voltages; a field effect transistor having source and drain electrodes interconnecting said first and second output terminals and a gate electrode for selectively receiving an energizing voltage to thereby render said field effect transistor conductive; and a voltage supply connected to said field effect transistor gate electrode for initially supplying said energizing voltage to said gate electrode when power is first supplied to said apparatus and for terminating said energizing voltage after a predetermined duration, said voltage supply comprising an R-C circuit connected across an operating voltage source, the junction defined by the series connected resistor and capacitor included in said R-C circuit being connected to said field effect transistor gate electrode, such that when said power is first supplied, the operating voltage provided by said operating voltage source is applied to said junction through said capacitor, the junction voltage decreasing as said capacitor is charged.
Claim 2
Dependent Claim
289 words
An automatic frequency control circuit for tuning apparatus, the tuning apparatus having an electronically variable frequency generating means, and the automatic frequency control circuit being responsive to the output produced by a frequency discriminator supplied with IF signals, comprising: a variable capacitance diode coupled to said variable frequency generating means, the frequency generated by said variable frequency generating means being a function of the capacitance value; a differential output DC amplifier connected to said frequency discriminator and having first and second output terminals across which said variable capacitance diode is coupled, said differential output DC amplifier providing first and second voltages at said first and second output terminals, respectively, having substantially the same magnitude and opposite polarity in accordance with the frequency of the IF signals, said variable capacitance diode exhibiting a capacitance value determined by the difference between said first and second voltages; a field effect transistor having source and drain electrodes interconnecting said first and second output terminals and a gate electrode for selectively receiving an energizing voltage to thereby render said field effect transistor conductive; and a voltage supply connected to said field effect transistor gate electrode for initially supplying said energizing voltage to said gate electrode when power is first supplied to said apparatus and for terminating said energizing voltage after a predetermined duration, said voltage supply comprising an R-C circuit connected across an operating voltage source, the junction defined by the series connected resistor and capacitor included in said R-C circuit being connected to said field effect transistor gate electrode, such that when said power is first supplied, the operating voltage provided by said operating voltage source is applied to said junction through said capacitor, the junction voltage decreasing as said capacitor is charged.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-09 | 1978-12-09 | 1979-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-09 | 1982-12-09 | 1983-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-09 | 1986-12-09 | 1987-06-10 | $7700.00 | Window Closed / Lapsed |