Designing a simple ADSR(-ish) envelope generator from scratch

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Working simulation on falstad: https://tinyurl.com/yz5z97jg

In this video, I'll walk you through the process of designing a super simple ADSR(-ish) envelope generator from scratch. After VCO and VCF, this is one of the fundamental building blocks for any modular synthesizer.

If you are a complete beginner and need help understanding some of the basic concepts, here's a list of links:

Using a breadboard:    • Complete beginner's guide to using a ...  
Op amp fundamentals:    • DIY SYNTH VCF Part 2: Active Filters ...  
Comparator close-up:    • Adding voltage controlled PWM to my VCO  
Analog filtering basics:    • DIY SYNTH VCF Part 1: Analog Filterin...  

And if you want to build along, here are the parts you'll need:

1x TL074
3x 100k resistor
1x 47k resistor
1x 10k resistor
1x 1k resistor
1x 100k linear mono potentiometer
2x 1M log mono potentiometer (linear works too, i'm using them in the video, log is better though cause it allows for finer control)
2x 1uF foil/film capacitor
5x 1N4148 diode

Optional:
1x LED
1x 2k resistor

Chapters:
00:00 Intro
02:44 Passive A/R Envelope
10:45 Active A/R Envelope
18:19 Faking an ADSR Envelope
26:50 Final Sound Demo & Outro