Things are going to take a vintage turn during the next few weeks. I’m knocking out a few 60’s backing tracks, returning to classic combo organ sounds. As a teen, I owned and played a Farfisa Mini Compact Deluxe. As a neophyte engineer, I was also interested in rolling my own gear — a great entry-way to audio electronics. [Not drugs.]
Thanks to our move, I uncovered, literally, a small number of brochures and data sheets from the 70’s and 80’s era. Today’s subject is the Texas Instruments SN76477 Complex Sound Generator.
The SN76477 was an all purpose, mixed signal (digital+analog) noise maker, appearing in games, toys and other mass market consumer electronics. Its temperature stability was none-to-good, making it a poor choice for musical instrument design. It excels, however, at cheesy 1980’s sound effects.
I built the SN76477 sound demonstration circuit (below) into a “busy box” for our son. Unfortunately, the busy box and the SN76477 is lost and gone. Only the data sheets and application notes remain in its place. If you find an SN76477, it’s most likely a “pull” from an old toy and probably not new old stock (NOS).
Here are links to the SN76477 data sheets and application guide. All of the files are PDF.
- SN76477 Data Sheet (July 1978)
- Complex Sound Generation Using The SN76477N (Guide)
- SN76477 Data Sheet (Preliminary, Oct 1977)
- SN76477 Sound Development System Schematic
I apologize for the yellow pages, but we are talking true vintage! The sound development system schematic is brittle and requires careful handling.
TI wrote a very compresensive SN76477 guide, so there isn’t too much point in detailing the SN76477 here. If you’re going to experiment with the SN76477, the TI guide is a must-read. The guide describes a few of the internal circuits as well as sample application circuits.
Copyright © 2021 Paul J. Drongowski