Leigh Klotz, author of Ham Radio for Arduino and PICAXE, gave us this interesting chip from the 80’s to play with: a UM3482A “Multi Instrument Melody Generator” IC. While not quite rare, it is a bit of a vintage curiosity these days, and we wired one up to see what exactly it does.
The vintage Radio Shack Archer package it came in was minimalist (though not quite this minimalist as it came to us– imagine that the chip were still there in the bubble). It promises not just 12 tunes, but circuit diagrams as well.
This Archer-branded datasheet (including the promised circuit diagrams) came stapled to the back. You can download a readable copy of the manufacturer’s original datasheet here.
“A mask-ROM-programmed multi-instrument melody generator, implemented in CMOS technology. It is designed to play the melody according to the previously programmed information and is capable of generating 12 songs with 3 different effects: piano, organ, and mandolin.”
Amongst the twelve musical selections are London Bridge, Row Row Row Your Boat, Oh My Darling Clementine, and (of course) Happy Birthday. Suggested applications included toys, door bells, music boxes, and telephones. (File under: Customized ringtones of the 80’s?)
The three little graphs in the upper right show the three different timbres (the “instruments,” in the phrase “multi-instrument”) in terms of amplitude versus time. The other diagrams show how to wire it up to a speaker and how to configure the various inputs to select which song to play and so forth.
We breadboarded up a sample circuit from the datasheet, substituting with parts we had on hand, including a little magnetic buzzer as the speaker. A 2xAA battery holder is connected up to the power and ground rails. There is a momentary button switch to select the next melody in the set, and a row of DIP switches to set the configuration options.
And sure enough, it plays melodies.
I can’t tell if the instrument in that loop is a piano, organ, or mandolin.
But it looks intriguing enough for me to buy one on eBay!
I used one of these back in the 80’s for a Christmas present for my (then) 3 year old nephew. I don’t remember anymore exactly how I did it (It was a 555 timer and a couple of logic IC’s) but I had it rigged so you hit a momentary switch and it would randomly select a tune and timbre and play it. He just loved that thing and drove everyone nuts with it (I had to add a volume control by special request)
Now my nephew is in his late 20’s and has a 3 year old of his own …. and I’m probably giving away my age ……
Ha! I still have that chip. Though, I seem to have misplaced the data sheet. I bought it in the infancy of my interest in hobby electronics, but never did anything with it.
I’ve also got a TLC548 Analog-To-Digital Converter IC. The data sheet for that one gives example circuits and assembly code for interfacing with various microprocessors, such as the Z80, Intel 8051/52, and Motorola 680X.
…Holey moley. My parents’ home still has the doorbell that uses that chip. Dad made a lot of Heathkit projects back in the day. (And he taught me how to solder on the 25″ diagonal TV kit he built in the early 70s! Brave man!)