Next step in my current electronics project, after idea and schematics, is prototyping. Here is working prototype assembled on breadboard using lab equipment (like power supply etc). In top-left corner is zero-level cross detector, it converts any periodic signal with amplitude from 1 to 5V into square signal with 0 to 5V amplitude, pretty much digital one.
In bottom right corner Atmel’s ATTiny 2313 that measures frequency of this signal and shows it on display.
On the bottom USB Tiny flash programmer.