Simple Amplifier

I built an amplifier! This little fella is going to replace the big old amp that I use to hear my electric drumkit. I have made amplifiers before, but this one is by far the best-sounding (and most powerful) one so far.

It’s made using only three transistors, two of which are the big boys you see in the photo above. They come from an old amplifier that I got from a friend and took apart for, well… parts.

The schematic shows how everything fits together. Transistors Q2 and Q3 form a push-pull configuration, and are biased by diodes D1 and D2. Transistor Q1 amplifies the signal; its bias is automatically corrected by the feedback resistor R6.

Since it’ll be sitting in the same spot connected to the same things, it just has some solder connections. The audio inputs will get jack connectors, and the speaker will just be soldered on.

The PCB I made myself using UV exposure, etching with sodium persulfate, and some drilling. One day I’ll make some videos about the entire process.

I already have plans for the next amplifier, which will be stereo and have a volume knob and some actual connectors :)