An electronic switch for audio signals can be achieved using electronic diagram below. Electronic circuit diagram of the electronic switch allows switching of audio signals without introducing switching noise.
A very simple audio mixer using operational amplifier can be designed using electronic scheme in the figure below. The audio mixer uses a TL071 operational amplifier, but can be used TL081 and a type 741 operational amplifier in adder configuration. Individual input signals are applied through mixing potentiometers, the strength of 100k from the inverting input of operational amplifier.
Using lm2896 integrated amplifier manufactured by National Semiconductor can be designed using few electronic components. The audio amplifier can provide a maximum power of 2.5 watts per channel on a 8 ohm load or a power of 9 W at a bridged connection. Circuit requires a continuous supply voltage of 12 volts.
Resistances R1 and R2 together with capacitor C2 form a negative feedback loop. Bandwidth of the amplifier is given by R2 and C3. R3 and C4 ensure maximum gain, while R4 and C6 output stabilizes. Supply filter capacitor C8, eliminate any peak that might occur.