Music volume control (LF356) circuit

Published:2011/5/6 21:23:00 Author:TaoXi | Keyword: Music volume | From:SeekIC

The Music volume control (LF356) circuit is as shown. This circuit can be used in Kara OK audio equipment and it also can be used to control the microphone music volume automatically and weak the base music. FET T1 (2N3819) can be used as the variable resistor, R1 and T1 constitute the divider circuit, T1's equivalent resistance is controlled by the control voltage of T1's control gate, the gate control voltage is amplified and rectified, filtered by the audio signal. This control voltage changes with the input signal, and the partial pressure ratio of the input signal changes too, that changes the music signal components which are sent into the op amp inverting input port. This circuit uses the FET input-type integrated operational amplifier LF356. As the circuit is the inverse proportion operation, so the input resistance is small (less than 470kΩ), the half-power bandwidth is about 5Hz ～500kHz, the gain range is 0～-38dB, the input signal amplitude should not exceed 8Vp-p. The main parameters of the integrated operational amplifier LF356 (typical):



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