Mini Stereo Amplifier
A simple mini stereo amplifier, which based on 2 chips. As pre-amp, there the MC1458 dual op amp, and the LM378 work as dual 4-watt amplifier.
The gain of pre-amp provide by ratio of R3/R1 for the one side, and the other side by R4/R2. In this case, the ratio is about 100, and can be varied by enhanced the ratios. Pin 2 as input from the left channel, and pin 6 as the right one. The output from U1 are coupled through C5/R10 and C3/R6 to U2.
This circuit using 9V for the fuel and dual 8 Ohm speaker as the driver of the output.
[source:Electronics Circuit]