AdnanSamra:
hi every one i need to know something please , since we are using pin 11, & 12 for arduino Mega 2560 to out put the sound using tone(AC) and there is no GND connection how can i use a push pull transistor output B class amplifier stage to an 8 ohm speaker? how can i connect this out put to the common bases of the npn & pnp transistors?
Ground alternates with toneAC, so you can't use a transistor. But, you wouldn't need to use toneAC if you're going through a amplifier as you don't need to use toneAC to increase the volume.
Maybe I should ask, why are you wanting to use toneAC with an amplifier?
Tim