Very simple audio amplifier. Input signal volume is setted by the 10K trimmer. The main stage is the non-inverting OpAmp which gains (1+9k/1k) = 10. The amplified signal goes to the speaker after a BJT push-pull output stage. The divider gives the 2,5V offset to the OpAmp to set the input signal on the range center in case of single supply voltage between ground and +5V.
I've been asked to use a low voltage supply, around 5V, and a 8 Ohm speaker. For a first prototype I'm going to try an LM358N OpAmp IC.
Any suggestion for improving all my circuits are always well accepted.