US3935513A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protective circuit for transistor amplifier
Assignee: Sony Corp
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Filing: 1974-07-08
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Granted: 1976-01-27
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Expires: 1994-07-08
Abstract
Abstract A protective circuit for a transistor amplifier is disclosed which includes a load impedance detecting circuit provided between an output terminal of a transistor amplifier and a load terminal, a circuit for detecting an abrupt surge voltage of a voltage source for the amplifier and a muting circuit are provided between an input terminal of the amplifier and a reference point, the muting circuit being operative to limit an input signal applied to the input terminal of the amplifier in response to output signals of the load impedance detecting circuit. A protective circuit having a thermal sensing circuit for detecting a temperature rise of an output transistor above a predetermined level which shuts off the amplifier is described as one embodiment.
Inventors
- 👤 Tadao Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:42
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/52; H02; H02H; H02H3/00; H02H3/02; H02H3/06; H02H3/38; H02H5/00; H02H5/04; H02H5/042
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
234 words
A transistor amplifier protective circuit comprising: an input terminal supplying an input signal to said transistor amplifier, a first transistor with its emitter-collector electrodes connected between ground and said input terminal to short said input signal to ground when said first transistor conducts, a first resistor with one side connected to the output of said transistor amplifier, a load connected between ground and the other side of said first resistor, second and third transistors with the collectoremitter path of said second transistor connected between the output of said transistor amplifier and the control electrode of said third transistor, a first capacitor connected between the control electrode of said second transistor and the output of said transistor amplifier, a fourth transistor with its control electrode connected to the emitter-collector path of said third transistor, a bias voltage of a first polarity, and the emitter-collector path of said fourth transistor connected between the control electrode of said first transistor and said bias voltage of a first polarity, a second capacitor connected between said bias voltage of a first polarity and the control electrode of said fourth transistor, a second resistor connected between ground and the control electrode of said fourth transistor, a third resistor connected between the other side of said first resistor and the control electrode of said second transistor, and a fourth resistor connected between ground and the control electrode of said second transistor.
Claim 2
Dependent Claim
234 words
A transistor amplifier protective circuit comprising: an input terminal supplying an input signal to said transistor amplifier, a first transistor with its emitter-collector electrodes connected between ground and said input terminal to short said input signal to ground when said first transistor conducts, a first resistor with one side connected to the output of said transistor amplifier, a load connected between ground and the other side of said first resistor, second and third transistors with the collectoremitter path of said second transistor connected between the output of said transistor amplifier and the control electrode of said third transistor, a first capacitor connected between the control electrode of said second transistor and the output of said transistor amplifier, a fourth transistor with its control electrode connected to the emitter-collector path of said third transistor, a bias voltage of a first polarity, and the emitter-collector path of said fourth transistor connected between the control electrode of said first transistor and said bias voltage of a first polarity, a second capacitor connected between said bias voltage of a first polarity and the control electrode of said fourth transistor, a second resistor connected between ground and the control electrode of said fourth transistor, a third resistor connected between the other side of said first resistor and the control electrode of said second transistor, and a fourth resistor connected between ground and the control electrode of said second transistor.
Claim 3
Dependent Claim
45 words
A transistor amplifier protective circuit according to claim 1 further including a first diode connected between said first and third resistors, a second diode connected between ground and said fourth resistor and said first and second diodes poled to pass current in the same direction.
Claim 4
Dependent Claim
41 words
A transistor amplifier protective circuit according to claim 2 including a Zener diode connected between ground and the control electrode of said first transistor, and a bias voltage of a second polarity connected to said control electrode of said first transistor.
Claim 5
Dependent Claim
29 words
A transistor amplifier protective circuit according to claim 3 including a thermistor connected between said bias voltage of a first polarity and a tap point on said second resistor.
Claim 6
Dependent Claim
126 words
A transistor amplifier protective circuit according to claim 1 including a second transistor amplifier, a second input terminal supplying an input to said second transistor amplifier, a fifth transistor with emitter-collector electrodes connected between ground and said second input terminal and its control electrode connected to the control electrode of said first transistor, a sixth resistor with one side connected to the output of said second transistor amplifier, a second load connected between ground and the other side of sixth resistor, a sixth transistor with its emitter-collector electrodes connected between the control electrode of said third transistor and the first side of said sixth resistor, and a third capacitor connected between the control electrode of said sixth transistor and said first side of said sixth resistor.
Claim 7
Dependent Claim
55 words
A transistor amplifier protective circuit according to claim 5 including a fourth diode, a seventh resistor, an eighth resistor and a fith diode connected in series between ground and the second side of said sixth resistor, and the control electrode of said sixth transistor connected to the junction point between said seventh and eighth resistors.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-01-26 | 1979-07-28 | 1980-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-26 | 1983-07-28 | 1984-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-26 | 1987-07-28 | 1988-01-27 | $7700.00 | Window Closed / Lapsed |