Using electronic diagram below, through a single switch is possible to choose one of four separate stereo channels. Internal switch is made by CMOS components, to avoid cracking that usually occur in mechanical switches.
Two type D flip-flops IC2 were assigned a divider role by connecting outputs to D inputs . Q output of FF1 is connected to the clock input of FF2, resulting in a four-bit counter.
Gates outputs control switches of CMOS IC3 and IC4.
Using this electronic circuit can be made an audio distortion level meter indicator circuit project for power gain provided by an amplifier module that does not react or react with difficulty at of short duration peaks of power. This audio distortion level meter indicator circuit is controlled by the output of an amplifier stage of AF.
The transistor T1 make a voltage regulator. The values of R1 and R2 depend on the supply voltage and can be replaced using values from the table below.