AD envelope generator
- Synth Secrets, Part 3: Modifiers & Controllers
- Synth Secrets, Part 7: Envelopes, Gates & Triggers
- Synth Secrets, Part 8: More About Envelopes
- Digisound 80 80-10 Voltage Controlled Envelope Generator, CEM3310 based. Electronic Music Circuits by Barry Klein,1982, p. 62-3, includes Charles Blakey's independent trigger input modification.
- Digisound 80 80-8 Dual ADSR, CEM3310 based
- Digisound 80 80-18 Dual Multi-Function Envelope Generator, CEM3310 based
- Formant music synthesizer by C. Chapman, Elektor, 1978, p. 64, using op-amps and common discrete components
- yusynth ADSR has a 555 core with a few op-amps.