Muti-channel audio mixer circuit based on LM3900 IC. Four channels

Posted on Feb 6, 2014

A simple multi-channel audio mixer circuit using LM3900 quad amplifier is given below. The circuit consists of 4 channel quad amplifier (LM3900). Two mic audio inputs and two direct line inputs are available in this circuit. By adding the same circuit parallel with this, you can increase the number of inputs according to the applications. Each inp

Muti-channel audio mixer circuit based on LM3900 IC. Four channels
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ut is connected to the inverting terminal of LM3900. The built in amplifier of each section amplifies every audio input separately and is fed to the output terminals. The output terminal from each channel is connected to a single output line with a resistance not greater than 680K and produces a mixed audio at the output with very low noise. This audio mixer circuit doesn`t use a low impedance input to mix idealsources. Capacitors C1 to C4 are the decoupling capacitors for the corresponding channels. C5 is the output decoupling capacitor. LM3900 series amplifiers consist of four independent and internally compensated amplifiers that are designed for single and wide power supply voltage. These amplifiers provide a wide range of voltage inputs and very good response for all audio frequencies. They also provide a large output swing.

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