A two-channel mixing desk can be made using electronic diagram below. This mixing console lets you mix the two audio signals are alternated with a frequency of 100kHz clock by four MOS switches. Clock frequency of 100kHz is produced by the N4-N6 consists of inverters. By overlapping clock signal with a DC voltage inverters N1 and N2 entry arises from a report break out of N2 clock signal P1 adjustable. The same signal but inverted is located at the exit of N3. These two switches control signals S2, S3 respectively S1, S4.
A dynamic microphone preamplifier can be realized using LM387 integrated circuit. LM387 is a dual operational amplifier manufactured by National Semiconductor. Input impedance corresponds to 47k, it depends almost exclusively by R1. If you wish to connect a dynamic microphone with a different value, the resistance R1 can be changed. Dynamic microphone preamplifier amplification was set at 40dB. Input impedance of the amplifier where it will connect the preamplifier must be at least 100k.
A very simple class B power amplifier electronic project can be designed using TDA8560 audio IC. The TDA8560 amplifier has an internally fixed voltage gain for excellent channel balance . This audio amplifier electronic project will provide a dual 40 watt output power . This audio amplifier IC is specially designed for car audio applications.