Patent US3918088A successfully refreshed from Google Patents.
US3918088A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power supply circuit for varying the bias signal to a magnetic head
Assignee: Sony Corp
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Filing: 1974-06-03
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Granted: 1975-11-04
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Expires: 1994-06-03
Abstract
Abstract A bias curcuit for a tape recorder is provided where an input voltage of the bias oscillator is changed in accordance with a magnetic tape material.
Inventors
- 👤 Hideo Tabuchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 15:18
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/02; G11B5/027; G11B5/03
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
126 words
Means for varying the bias signal to a magnetic head comprising, a variable gain bias oscillator connected to said magnetic head and having a gain control input terminal, a control transistor with one of its electrodes connected to said gain control terminal, A bias voltage source with one side connected to a second electrode of said control transistor, a first resistor connected between the third control electrode of said control transistor and the other side of said bias voltage source, a first switch and a second resistor connected in series and the combination connected in parallel with said first resistor and third and fourth resistors connected in series between said one side of said bias voltage source and said third control electrode of said control transistor.
Claim 2
Dependent Claim
126 words
Means for varying the bias signal to a magnetic head comprising, a variable gain bias oscillator connected to said magnetic head and having a gain control input terminal, a control transistor with one of its electrodes connected to said gain control terminal, A bias voltage source with one side connected to a second electrode of said control transistor, a first resistor connected between the third control electrode of said control transistor and the other side of said bias voltage source, a first switch and a second resistor connected in series and the combination connected in parallel with said first resistor and third and fourth resistors connected in series between said one side of said bias voltage source and said third control electrode of said control transistor.
Claim 3
Dependent Claim
81 words
Means for varying the bias signal to a magnetic head according to claim 1 including a second switch and a fifth resistor, a shunt transistor with its control electrode connectable to said one side of said bias voltage source through said switch and fifth resistor, a second electrode of said shunt transistor connected to said other side of said bias voltage source, and a third electrode of said shunt transistor connected to the junction point between said third and fourth resistors.
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) | 1978-11-03 | 1979-05-05 | 1979-11-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-03 | 1983-05-05 | 1983-11-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-03 | 1987-05-05 | 1987-11-04 | $7700.00 | Window Closed / Lapsed |