I've built a very simple VCO based on a UJT transistor.
It outputs on a 8-ohm speaker but sound is like really, really low. So, I'm looking for an amplifier to build, something simple to amplify the sound. I've tried a few circuits from the web but whether it doesn't sound or gain is negligible.
I've been told it should be doable with 2N2222 transistor or 2N3904 which would be great since I have those. I also have a couple of sound transformers which might be useful. I don't really know, I'm quite a beginner in electronics.
How can I build a simple amplifier from a 2N2222 or 2N3904 transistor to amplify a signal from a VCO? How could I improve this circuit?