Here is a simple, little circuit that makes loud, useless noises with an ATtiny45 programed in Bascom-AVR.

In the May 1979 edition of Elektor we published a “Simple Sound Effects” unit. The author was rightly proud of the design which used a CD4040 counter, a CD4049 Hex inverter and a few odds and ends. Anyone who considered building the circuit all those years ago will be happy to know that a newer version is now available. Thanks to the marvels of modern technology we can now make the same sort of racket but with fewer components. That’s progress!

What we can’t see from the circuit diagram is how much hardware and wiring of the original design containing counters and inverters has been saved. The 21st century version does the same job in software and uses little more than just an 8-pin ATtiny45 microcontroller instead of the clever feedback counter design of the original circuit.

The design also uses a single transistor buffer at the output to increase the level of annoyance produced from the small 8-Ω loudspeaker.

A trimpot is included in the design to give some degree of frequency adjustment of the generated rumpus.

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For those who don't like microcontrollers or who just want to play aroud with logic and other classic components, attached below is the original design.