I have been trying to get this circuit working on the breadboard for a while now. I would like to stress how important and convenient it is to have extra chips on hand when prototyping. It’s dictates the difference between moving on within a day, or tearing your hair out for weeks trying to figure out if everything is wired correctly questioning yourself if you even know how to read a schematic. It was a nice feeling when a replacement chip worked first attempt. I had a blown chip the entire time.
Forest M. Mimms III calls this circuit the “Stepped-Tone Generator”, he demonstrates it in his Engineer’s Mini Notebook Vol I on page 26 and describes the sounds as “resembling plucked violin strings”. Although, the circuit caught much popularity as the hobbyist community decided it sounded much more like an old Atari video game console. From there, it has been altered, changed and hacked into many different awesome things. It’s usual for it to be found built or shoved into some small obscure enclosure found around the house. It’s a very simple circuit that produces lots of fun.
Kaustic Machines is largely responsible for making the circuit what it is today.
It’s common to see different values of pots used, as well as the variation of either an 8ohm loudspeaker or -4db line output.
This is my first successful build of the circuit. All I have for a pot is a 250k from an old guitar. The secondary pot from pin 12 is just a 10k resistor.
I’m going to follow up this post with some more fun things in the near future.