Building on that concept, the next objective was to create an even smaller FM radio compact enough to fit inside an earbud.

Making a servo tester using an Attiny85 micro chip, Attiny45 also works for this project. This diy servo tester is as good as ...

The audio component centers around the SS8550 PNP transistor (Q1) which serves as a driver for the passive buzzer (BZ1). This ...