发明授权
US5793874A Control circuit 失效
控制电路

Control circuit
摘要:
A volume control device is inserted in the circuit between the output of a sound system amplifier and a speaker. The volume control device measures ambient noise in the music environment and adjusts the power transferred to the speaker, such that the output volume of the speaker increases and decreases with changes in the ambient noise. A variable throughput current device, such as a thermistor or a transistor, is connected in the speaker circuit to control a power transfer to the speaker. A comparator compares the output of an ambient noise detector with the signal applied to the speaker and the variable throughput current device is adjusted in accordance with the compared signals. A level detect circuit serves to maintain the speaker volume at a preset level when the amplifier output drops below a predefined signal level. The speaker may be provided with a sensing coil generating an output signal representative of the level of ambient noise in the vicinity of the speaker.
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