4 channel audio mixer using the LM381 IC low noise dual preamplifier. Each of the two amplifiers is completely independent lm381, with each internal power supply decoupler-regulator with 120 dB of rejection of the offer and 60 dB channel separation. Other features include high gain (112 dB), large output voltage swing (VCC b 2V) pp and wide power band width (75 kHz, 20 Vp-p).High gain operational amplifier combines four individual input signals. The DC power supply should be well filtered, and the circuit must be protected to avoid picking up hum. If you need more audio inputs that can add more inputs by connecting another capacitor 1uF in series with a 500k pot to the network.
To supply the project audio mixer electronic circuit can use a DC power supply (or battery) that will provide an output voltage between 9 and 24 volts.
