Ringer is a Kosmo format DIY synth module built around the AD633 chip. If you need to you can press it into service as a 2-channel mixer or a voltage controlled amplifier, but what it really is useful for is something like ring modulation — combining two simple waveforms to make a much more complex sound.

Git repository: https://gitlab.com/rsholmes/ringer

Music: Ringtone by Rich Holmes

Analog Output blog, and links to other AO sites, here: https://richholmes.xyz/analogoutput/