Patent US3812435A successfully refreshed from Google Patents.
US3812435A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pulse width stabilized blocking oscillator
Assignee: AT&T Inc
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Filing: 1972-12-26
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Granted: 1974-05-21
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Expires: 1992-12-26
Abstract
Abstract A blocking oscillator includes a pulse width control circuit which diverts base current from the base drive of the blocking oscillator transistor. This permits the blocking oscillator transistor to turn off and establish a predetermined pulse width independently of its Beta characteristic and the supply voltage energizing the blocking oscillator.
Inventors
- 👤 R Ostapiak
- 👤 R Scuderi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:11
CPC Classifications
H; H03; H03K; H03K3/00; H03K3/02; H03K3/26; H03K3/30
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
217 words
A blocking oscillator comprising a power transistor having a main conduction path and a control electrode, a regenerative feedback transformer including a primary winding connected to the main conduction path and a secondary winding connected to the control electrode, a resistor and capacitor connected in series and connected to said control electrode, wherein the improvement comprises, a third winding wound on said transformer, a first breakdown diode shunting said secondary winding, a second breakdown diode having a lower breakdown threshold than said first breakdown diode and shunting said third winding, a control transistor, including a main conduction path and a control electrode, said main conduction path of said control transistor being connected to the control electrode of said power transistor, said resistor, said first breakdown diode, said second breakdown diode, and a junction of the main conduction path and the control electrode of said control transistor being connected into a closed loop, said first breakdown diode being poled to break down in response to the feedback current of said secondary winding and said second breakdown diode being poled in an opposite direction to said first breakdown diode, whereby the voltage drop across said resistor offset by the opposing voltage drops across said first and second breakdown diodes activates said control transistor to turn off said power transistor.
Claim 2
Dependent Claim
217 words
A blocking oscillator comprising a power transistor having a main conduction path and a control electrode, a regenerative feedback transformer including a primary winding connected to the main conduction path and a secondary winding connected to the control electrode, a resistor and capacitor connected in series and connected to said control electrode, wherein the improvement comprises, a third winding wound on said transformer, a first breakdown diode shunting said secondary winding, a second breakdown diode having a lower breakdown threshold than said first breakdown diode and shunting said third winding, a control transistor, including a main conduction path and a control electrode, said main conduction path of said control transistor being connected to the control electrode of said power transistor, said resistor, said first breakdown diode, said second breakdown diode, and a junction of the main conduction path and the control electrode of said control transistor being connected into a closed loop, said first breakdown diode being poled to break down in response to the feedback current of said secondary winding and said second breakdown diode being poled in an opposite direction to said first breakdown diode, whereby the voltage drop across said resistor offset by the opposing voltage drops across said first and second breakdown diodes activates said control transistor to turn off said power transistor.
Claim 3
Dependent Claim
210 words
A blocking oscillator comprising, a power transformer having first, second, and third windings, a power transistor having a control electrode and a main conduction path, the main conduction path of said power transistor being connected to said first winding, a timing capacitor coupled to the control electrode of said power transistor and to said second winding, a pulse width control circuit comprising a control transistor having a main conduction path and a control electrode, the main conduction path of said control transistor being connected to the control electrode of said power transistor to control the turnoff of said power transistor, a resistor, a first breakdown diode to establish a reference voltage shunting said second winding and connected in series with said resistor, said first breakdown diode coupling said timing capacitor to the control electrode of said power transistor, a second breakdown diode coupling said timing capacitor to the control electrode of said control transistor, said third winding connected in a path parallel to said second breakdown diode, whereby said first breakdown diode and the resistor control the charging of said timing capacitor, and said second breakdown diode energized by said third winding generates a voltage to linearly shift the voltage supplied by said timing capacitor to switch said control transistor.
Claim 4
Dependent Claim
210 words
A blocking oscillator comprising, a power transformer having first, second, and third windings, a power transistor having a control electrode and a main conduction path, the main conduction path of said power transistor being connected to said first winding, a timing capacitor coupled to the control electrode of said power transistor and to said second winding, a pulse width control circuit comprising a control transistor having a main conduction path and a control electrode, the main conduction path of said control transistor being connected to the control electrode of said power transistor to control the turnoff of said power transistor, a resistor, a first breakdown diode to establish a reference voltage shunting said second winding and connected in series with said resistor, said first breakdown diode coupling said timing capacitor to the control electrode of said power transistor, a second breakdown diode coupling said timing capacitor to the control electrode of said control transistor, said third winding connected in a path parallel to said second breakdown diode, whereby said first breakdown diode and the resistor control the charging of said timing capacitor, and said second breakdown diode energized by said third winding generates a voltage to linearly shift the voltage supplied by said timing capacitor to switch said control transistor.
Claim 5
Dependent Claim
28 words
A blocking oscillator as defined in claim 2 wherein, the breakdown voltage of said first breakdown diode is greater than the breakdown voltage of said second breakdown diode.
Claim 6
Dependent Claim
43 words
A blocking oscillator as defined in claim 2 wherein said first and second breakdown diodes and a junction of the control transistor are connected to form a closed loop and a voltage divider shunting said second breakdown diode and including said third winding.
Claim 7
Dependent Claim
177 words
A blocking oscillator comprising a power transistor having a main conduction path and a control electrode, a timing network, a regenerative feedback transformer including a primary winding, a second feedback winding, and a third feedback winding, a first breakdown diode and a resistor connected in series and connecting said timing network to the second feedback winding, said first breakdown diode poled in a direction to break down in response to the feedback signal of said second feedback winding, a control transistor having a main conduction path and a control electrode, the main conduction path of said control transistor being connected to divert current from the control electrode of said power transistor in order to control the switching of saiD power transistor, a second breakdown diode energized in a breakdown mode by said third feedback winding and connecting said timing network to the control electrode of said control transistor, said first breakdown diode having a higher breakdown threshold than said second breakdown diode in order to generate a control voltage differential to bias said control transistor into conduction.
Claim 8
Dependent Claim
177 words
A blocking oscillator comprising a power transistor having a main conduction path and a control electrode, a timing network, a regenerative feedback transformer including a primary winding, a second feedback winding, and a third feedback winding, a first breakdown diode and a resistor connected in series and connecting said timing network to the second feedback winding, said first breakdown diode poled in a direction to break down in response to the feedback signal of said second feedback winding, a control transistor having a main conduction path and a control electrode, the main conduction path of said control transistor being connected to divert current from the control electrode of said power transistor in order to control the switching of saiD power transistor, a second breakdown diode energized in a breakdown mode by said third feedback winding and connecting said timing network to the control electrode of said control transistor, said first breakdown diode having a higher breakdown threshold than said second breakdown diode in order to generate a control voltage differential to bias said control transistor into conduction.
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) | 1977-05-20 | 1977-11-19 | 1978-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-20 | 1981-11-19 | 1982-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-20 | 1985-11-19 | 1986-05-21 | $7700.00 | Window Closed / Lapsed |