ZX SOUND CARDS
42 years ago... (as of 2025)
In 1983 two specific magazine articles sparked my interest and imagination. Both were designed as peripherals for the ZX-81 and ZX-Spectrum. Both used General Instrument's AY-3-891x (PSG) sound chips. Both projects were beyond my reach. I likely could have made the circuit board for one of them and saved up for the components, but before too long my Speccy died and went back to Uncle Clive. It was replaced with a Commodore 64 and the need for a PSG sound-card vanished. But I never quite lost the fascination for the PSG.
So good I built them both!
Two things happened recently:
- I acquired my first Spectrum in 42 years.
- AY-3-891x projects have become quite popular (specifically on the Retro Hardware Discord).
Before I knew it I had found scans of the magazines, recreated the designs and they were being fabricated.
The Your Computer article included a Spectrum program called "minuetz" that plays randomly generated music according to rules set forth by Mozart. This program looks so good I just had to type it in (using 2025 technology, however). I've even come up with a way to modify the program to work with not only the Hobby Electronics board but any Spectrum AY-3-891x board you may have.
Everything you need!
I have created the sinclair-zx-psg github repo that contains all resources related to the two sound-cards and the minuetz program. The repo contains a little backstory, the circuit diagrams, board layouts and the software necessary to build and enjoy either of these two wonderful projects.
The gerber files for the PCBs are included in the repo, as are links to PCBWay projects should you wish to use them to make your PCBs.