This circuit is intended for low power use and is very easy to build.
NPN direct coupled to the PNP output transistor, I used a BC547C FOLLOWED BY A BC557 PNP
The 10nF caps in both stages form low pass filters. This reduces the hiss, which is especially useful for radio or when amplifying an electret microphone for speech. Its is a very simple amplifier that can be built and tested in 20 minuets or less.
This may be better for some applications than the high gain lm386 stage that I just built. This circuit has an advantage of using very much less power than a lm386. However, it won't power a typical 8 ohm loudspeaker.
It will always be a low power amp that is only useful for high (not super high like crystal earpiece) impedance headphones. Stereo headphones should be wired up in series. This provides about 60 ohms headphone load, shown on the EC circuit as a 60 ohm resistor...
Enjoy!
