What’s an ADSR envelope generator? If you are a big music hacker, you probably know. If you are like the rest of us, you might need to read [Mich’s] post to find out that it is an attack-decay-sustain-release (ADSR) envelope generator. Still confused? It is a circuit used in music synthesis. You can see a demo of the device in the video below.
Before the Altair–which was sort of the first hobbyist computer you could actually buy–electronics magazines were full of music synthesizer projects that had a lot in common with the analog computers of old. A lot of people took that very seriously and then computers took over the collective consciousness and we found musical hackers started working with (digital) computer-based synthesizers. But the old analog synth designs just won’t die. [Mich’s] ADSR is based on an ancient design, and the amount of information and additions he provides makes it worth a read, even if you don’t fancy building one.
In particular, [Mich] found the original circuit had some issues and–after building the circuit once–did the work it took to fix the problems. He’s documented what he found and how he fixed it in great detail. He also explains a lot of terminology and even how basic elements like a flip flop made of NOR gates works.
If you do decide to duplicate the unit, the PCB layout is online. There’s also advice about tweaking circuit values for your particular setup.