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SN76489 Chip-Based Synthesizer

Over the break, I took some time to put together an arduino-driven synth from this “instructable” by Brian Peters.

2015-02-03 17.36.47
Yeah, inside the radio case

This is a synthesizer made from four SN76489 chips. These chips appeared as a cheap audio solution in a number of old computers and game consoles, including the ColecoVision, NeoGeo Pocket, Sega Genesis (although the Genesis had another chip capable of FM Synthesis).

Because these chips are cheap, this ends up being the cheapest synth on my rack:

$19.00 – Teensy 2.0 Board
$4.50 – 4x SN76489AN Chips (includes shipping)
$1.30 – 1.8432 MHz Oscillator
$0.10 – 4x 75k Resistors
$0.10 (or so) – 4x 10µF Capacitors
$5.00 – 4x 1/4″ Audio Jacks (these were way too expensive on Sparkfun)
$5.00 – Breadboard

$45.00 – Total (give or take)

So, it’s been about 15 years since I bought it, but I think that’s even cheaper than my Alesis Nanobass (appears in the background of these photos).

Why did I put it inside and old radio? Because that was what I found a Goodwill for $2 that was an appropriate size.

The aptly named Arduino "Teensy"
The aptly named Arduino “Teensy”

Teensy, SN76489 chips, and quartz clock ready for wiring
Teensy, SN76489 chips, and quartz clock ready for wiring

The rats' nest
The rats’ nest

So what does it sound like? Here’s a quick and dirty demo:

One thought on “SN76489 Chip-Based Synthesizer

  1. I’m currently trying to find a junk Sega Genesis system that I can use as a case (after I rip the guts out), as that seems more appropriate.

    If anyone have one for cheap let me know!

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