Patent US3902191A successfully refreshed from Google Patents.
US3902191A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transient suppression for tape player integrated circuit preamplifier
Assignee: Ford Motor Co
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Filing: 1974-04-19
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Granted: 1975-08-26
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Expires: 1994-04-19
Abstract
Abstract In a tape player the preamplifier integrated circuit can produce a transient, when the player is turned off, that will impress itself on the head thereby recording a noise signal on the tape. A circuit is shown for suppressing such transients. A diode is connected in series with the power supply so that when the player is turned off, the diode disconnects the preamplifier from the power supply. In addition a large value filter capacitor is connected across the preamplifier terminals so that the applied voltage can change only at a relatively slow rate.
Inventors
- 👤 Wilbur E Lynn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:46
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/181; H03F3/183; H03F3/187; G; G11; G11B; G11B5/00; G11B5/02; G11B5/027; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/34; H03G3/348
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
154 words
In a magnetic tape player circuit, said circuit comprising a tape head for producing electrical signals when in contact with a moving recorded magnetic tape, a preamplifier connected to said head for amplifying said electrical signals and having power supply terminals for energizing said preamplifier, and a switchable power supply for energizing said tape player, said circuit including a connection between said power supply and said power supply terminals of said preamplifier, said preamplifier having the characteristic of undesirably recording a noise burst on said tape via said tape head when said power supply is switched off and the voltage applied to said power supply terminals from said power supply falls rapidly, means for isolating said preamplifier power supply terminals from said power supply when said power supply is switched off, and means for reducing the rate of fall of voltage applied to said preamplifier when said isolating means acts to isolate said preamplifier.
Claim 2
Dependent Claim
154 words
In a magnetic tape player circuit, said circuit comprising a tape head for producing electrical signals when in contact with a moving recorded magnetic tape, a preamplifier connected to said head for amplifying said electrical signals and having power supply terminals for energizing said preamplifier, and a switchable power supply for energizing said tape player, said circuit including a connection between said power supply and said power supply terminals of said preamplifier, said preamplifier having the characteristic of undesirably recording a noise burst on said tape via said tape head when said power supply is switched off and the voltage applied to said power supply terminals from said power supply falls rapidly, means for isolating said preamplifier power supply terminals from said power supply when said power supply is switched off, and means for reducing the rate of fall of voltage applied to said preamplifier when said isolating means acts to isolate said preamplifier.
Claim 3
Dependent Claim
52 words
The circuit of claim 1 wherein said means for isolating is a diode connected between said one terminal of said power supply and one terminal of said preamplifier power supply terminals, and said means for reducing the rate of fall of voltage is a capacitor connected across said preamplifier power supply terminals.
Claim 4
Dependent Claim
12 words
The circuit of claim 2 wherein said preamplifier is an integrated circuit.
Claim 5
Dependent Claim
229 words
In a magnetic tape player circuit, said circuit comprising a magnetic tape Head for transducing the information on a moving magnetic tape to an electrical signal, an integrated circuit preamplifier having input signal terminals and a pair of power supply terminals, said input signal terminals being connected to said head so that said preamplifier will raise the level of said signal to a predetermined value, a power supply having an on-off switch, said supply connected to provide operating potential to said tape player and to said integrated circuit, said circuit having the undesirable characteristic of producing a current pulse in said head when said switch is turned from on to off thereby recording a noise pulse on said tape, the improvement comprising: a semiconductor diode connected between one terminal of said power supply and one of said preamplifier power supply terminals to isolate said preamplifier from said supply when said switch is turned from on to off, said diode poled to be in its conductive state when said power supply is turned on and in its nonconductive state when said power supply is turned off, and a capacitor connected between said power supply terminals of said preamplifier and being of sufficient capacitance to prevent the supply voltage applied to said preamplifier from changing rapidly, whereby said current pulse produced by turning said switch from on to off is avoided.
Claim 6
Dependent Claim
229 words
In a magnetic tape player circuit, said circuit comprising a magnetic tape Head for transducing the information on a moving magnetic tape to an electrical signal, an integrated circuit preamplifier having input signal terminals and a pair of power supply terminals, said input signal terminals being connected to said head so that said preamplifier will raise the level of said signal to a predetermined value, a power supply having an on-off switch, said supply connected to provide operating potential to said tape player and to said integrated circuit, said circuit having the undesirable characteristic of producing a current pulse in said head when said switch is turned from on to off thereby recording a noise pulse on said tape, the improvement comprising: a semiconductor diode connected between one terminal of said power supply and one of said preamplifier power supply terminals to isolate said preamplifier from said supply when said switch is turned from on to off, said diode poled to be in its conductive state when said power supply is turned on and in its nonconductive state when said power supply is turned off, and a capacitor connected between said power supply terminals of said preamplifier and being of sufficient capacitance to prevent the supply voltage applied to said preamplifier from changing rapidly, whereby said current pulse produced by turning said switch from on to off is avoided.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |