Patent US2237274A successfully refreshed from Google Patents.
EP0159079A2
Expired / Lapsed
EP
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Audio amplifier switch-on control circuit
Assignee: STMicroelectronics SRL
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Filing: 1985-03-30
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Granted: —
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Expires: 2005-03-30
Abstract
Abstract A capacitor (C,) which is progressively chargeable in response to the switching on of the equipment, however brought about, is associated with an oscillating circuit (CB) with intervention threshold. As the load voltage of said capacitor (C 1 ) increases the oscillating circuit (CB) shifts from a first to a second operating state, generating a switch-on current for the audio amplifier (A). The latter can be placed in stand-by condition by discharging to earth said capacitor (C 1 ) by means of a suitable switch (IS).
Inventors
- 👤 Sergio Palara
- 👤 Aldo Torazzina
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 18:04
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/30; H03F1/305
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
75 words
Audio amplifier switch-on control circuit in an audio signal generating apparatus, characterized in that it includes a progressively chargeable capacitor in response to the switching on of the equipment and an oscillating circuit with intervention threshold, which responds to the increase in load voltage of said capacitor beyond a preset value so as to shift progressively from a first to a second operating state for the generation of a switch-on current for the audio amplifier.
Claim 2
Dependent Claim
75 words
Audio amplifier switch-on control circuit in an audio signal generating apparatus, characterized in that it includes a progressively chargeable capacitor in response to the switching on of the equipment and an oscillating circuit with intervention threshold, which responds to the increase in load voltage of said capacitor beyond a preset value so as to shift progressively from a first to a second operating state for the generation of a switch-on current for the audio amplifier.
Claim 3
Dependent Claim
76 words
Control circuit according to claim 1, characterized in that with said oscillating circuit are associated two commutating devices with intervention threshold, the first of which is controlled by the load voltage of said capacitor and the second of which is controlled by the state of said first commutating device, said second commutating device acting on said oscillating circuit so as to place it in said first operating state after said load voltage reaches said preset value.
Claim 4
Dependent Claim
65 words
"Control circuit according to claim 2, characterized in that said oscillating circuit includes two opposed transistors, the first of which is controlled by said second commutating device for placing said oscillating circuit in said first operating state and the second of which is controlled by said first commutating device for the progressive shifting of the oscillating circuit from said first to said second operating state.
Claim 5
Dependent Claim
25 words
Control circuit according to claim 3, characterized in that said second transistor controls a first current generator for generation of the audio amplifier switch-on current.
Claim 6
Dependent Claim
35 words
Control circuit according to claim 4, characterized in that said first transistor controls a second current generator for the generation of a charging current for a capacitor controlling the inverting input of the audio amplifier.
Claim 7
Dependent Claim
47 words
Control circuit according to claim 5, characterized in that said control capacitor is selected so as to achieve a load voltage which prevails over the polarization voltage of the noninverting input of the audio amplifier for a time longer than the switch-on time of the audio amplifier.
Claim 8
Dependent Claim
20 words
Control circuit according to claim 1, characterized in that it includes a stand-by switch placed in parallel with said capacitor.
References Cited (Backward Citations)
No citation records indexed.
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