US3646397A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Amplifier protection circuit responsive to temperature and overcurrent
Assignee: Motorola Solutions Inc
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Filing: 1970-04-13
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Granted: 1972-02-29
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Expires: 1990-04-13
Abstract
Abstract A protection circuit for the transistorized power amplifier of a transmitter is provided in the form of a normally shunted reactive circuit coupled in series with the input to the power amplifier stage means of a current stepdown transformer. When excessive current is drawn by the power amplifier or when an excessive temperature is reached the shunting circuit is opened thereby connecting the reactive component in series between the driver stage and the power amplifier stage to partially detune the driver output, reducing the drive to the power amplifier stage.
Inventors
- 👤 Ross E Ruthenberg
- 👤 Joseph W Spells Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:26
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/52; H02; H02H; H02H5/00; H02H5/04; H02H5/041; H02H9/00; H02H9/02; H02H9/028
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
141 words
A protection circuit for an amplifier system having a driving stage producing driving signals and a driven stage responsive to the driving signals and subject to damage upon occurrence of a predetermined condition, the protection circuit including in combination: impedance means coupled in series between the output of the driving stage and the input of the driven stage of the amplifier system; relay means having normally closed relay contacts and an operating coil; shunt circuit means coupling the normally closed relay contacts across the impedance means for rendering the impedance means ineffective; and means coupled with the operating coil and responsive to the presence of said predetermined condition for causing sufficient current to flow through the operating coil to open the contacts, thereby rendering the impedance means effective to reduce the level of the driving signals applied to the driven stage.
Claim 2
Dependent Claim
141 words
A protection circuit for an amplifier system having a driving stage producing driving signals and a driven stage responsive to the driving signals and subject to damage upon occurrence of a predetermined condition, the protection circuit including in combination: impedance means coupled in series between the output of the driving stage and the input of the driven stage of the amplifier system; relay means having normally closed relay contacts and an operating coil; shunt circuit means coupling the normally closed relay contacts across the impedance means for rendering the impedance means ineffective; and means coupled with the operating coil and responsive to the presence of said predetermined condition for causing sufficient current to flow through the operating coil to open the contacts, thereby rendering the impedance means effective to reduce the level of the driving signals applied to the driven stage.
Claim 3
Dependent Claim
130 words
A protection circuit for an amplifier system having a driving stage producing driving signals and a driven stage responsive to the driving signals and subject to damage upon occurrence upon a predetermined condition, the protection circuit including in combination: impedance means including a transformer, the primary winding of which is coupled in series between the output of the driving stage and the input of the driven stage, and a reactive impedance means coupled with a secondary winding of the transformer; shunt means coupled across the reactive impedance means for rendering the reactive impedance means ineffective; and means responsive to the presence of said predetermined condition for disabling the shunt means, thereby rendering the reactive impedance means effective to reduce the level of the driving signals applied to the driven stage.
Claim 4
Dependent Claim
130 words
A protection circuit for an amplifier system having a driving stage producing driving signals and a driven stage responsive to the driving signals and subject to damage upon occurrence upon a predetermined condition, the protection circuit including in combination: impedance means including a transformer, the primary winding of which is coupled in series between the output of the driving stage and the input of the driven stage, and a reactive impedance means coupled with a secondary winding of the transformer; shunt means coupled across the reactive impedance means for rendering the reactive impedance means ineffective; and means responsive to the presence of said predetermined condition for disabling the shunt means, thereby rendering the reactive impedance means effective to reduce the level of the driving signals applied to the driven stage.
Claim 5
Dependent Claim
49 words
The combination according to claim 1 including further circuit means responsive to the opening of the relay contacts and coupled to a source of operating potential for maintaining the operating coil current at a level sufficient to maintain the contacts open irrespective of further changes in said predetermined condition.
Claim 6
Dependent Claim
85 words
The combination according to claim 2 wherein the reactive impedance means is capacitance means coupled across the secondary winding, the Shunt means comprises normally closed relay contacts coupled across the secondary winding, and the means for disabling the shunt means includes an operating coil for the relay contacts to open the same in response to a predetermined current flowing through the coil, and further including means responsive to the presence of said predetermined condition for causing said predetermined current to flow through the operating coil.
Claim 7
Dependent Claim
54 words
The combination according to claim 4 wherein the relay contacts are contacts of a reed relay further having a permanent magnet for biasing the contacts of the relay to a closed position, with said predetermined current through the operating coil of the relay overcoming the bias of the permanent magnet to open the contacts.
Claim 8
Dependent Claim
53 words
The combination according to claim 4 wherein the operating coil is coupled in series with the current supply to the driven amplifier stage and wherein the predetermined condition constitutes a predetermined current drawn by the driven amplifier stage, said predetermined current being sufficient to cause the operating coil to open the relay contacts.
Claim 9
Dependent Claim
98 words
The combination according to claim 6 further including a second operating coil and a temperature-sensitive resistance means with a negative temperature coefficient coupled in series with one another between a source of potential and a point of reference potential, with said second coil further being coupled with the relay contacts for opening said relay contacts in response to a second predetermined current through the second coil, said second predetermined current flowing when the temperature-sensitive resistance means is subjected to a predetermined temperature, and the temperature-sensitive resistance means being located for sensing the temperature of the driven amplifier stage.
Claim 10
Dependent Claim
73 words
The combination according to claim 4 wherein the predetermined condition is a predetermined temperature and the means for causing said predetermined current to flow comprises temperature-sensitive resistance means with a negative temperature coefficient coupled in series with the operating coil between a source of potential and a point of reference potential, so that said predetermined current flows through the operating coil when the temperature of the temperature-sensitive resistance means reaches said predetermined temperature.
Claim 11
Dependent Claim
133 words
The combination according to claim 8 wherein the temperature sensitive resistance means and the operating coil are connected at a first junction, and further including third impedance means connected at a second junction with the relay contacts in series between said source of potential and said point of reference potential, and unidirectional conductive means coupled between the first and second junctions, the unidirectional conductive means being reverse biased when the relay contacts are closed, with opening of the relay contacts forming a holding current path from the source of potential through the third impedance means, the unidirectional conductive means and the operating coil to said point of reference potential to maintain the operating coil current at a level sufficient to maintain the contacts open irrespective of the impedance of the temperature-sensitive resistance means.
Claim 12
Dependent Claim
29 words
The combination according to claim 9 including normally closed reset switch means for opening the current path through the operating coil upon actuation thereof to disable the holding path.
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) | 1975-02-28 | 1975-08-30 | 1976-02-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-28 | 1979-08-30 | 1980-02-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-28 | 1983-08-30 | 1984-02-29 | $7700.00 | Window Closed / Lapsed |