CAVE PROJECT! This information is here to support people who have been making MFOS gear since I started posting synth-diy information back in about 2002 or 2003. These projects have ALL been superceded by new and better designs. I do not recommend that you make these since they have been improved over the years. I am not providing any support for these projects beyond publishing this historical information.
This is an intermediate to advanced project and I do not recommend it as a first project if you are just getting started in synths or electronics. Only the circuit and some explanation are shown here. A lot of project building experience and electronics knowledge and equipment ownership (scope, meters, etc.) is taken for granted. If you are interested in building this project please read the entire page before ordering PC boards to ensure that the information provided is thorough enough for you to complete the project successfully.

Retriggerable ADSR Envelope Generator (New & Simpler)

This is a new Retriggerable ADSR Envelope Generator. This design is quite a bit simpler than the previous one and if you ask me its a lot better. It uses less ICs than the other one but it expects gate and trigger inputs that are already debounced and clean. Dirty gates or triggers will result in multiple envelopes starts. 

This schematic was created with Schematic Publisher (free from my site) and I used the schematic to bitmap function to create this image. After I got the bitmap in the clip board I pasted it into a paint program and saved it as a two color gif. If you web publish schematics you will want it!

In its quiescent state IC2-A's Q output is low as is pin 1 of IC1-A. The output of IC1-B (pin 4) is low and so is pin 1 of IC2-A. This results in both of the inputs of the MML NOR gate formed by CR5, CR6, R6 and IC1-C being low and its output (point R) being high. In this state the Release switch (IC3-C) is closed so that C4 is drained and the output is at 0 volts... More to come...

Retriggerable ADSR Envelope Generator Schematic

Retriggerable ADSR Envelope Power Connections

Mickey Mouse Logic NOR Gate

 


 
 

ADSR Envelope Generator Project Parts List


ADSR Envelope Generator Project Parts List

Qty. Description Value Designators
8   1/4 Watt 1% Resistor(s)   100K   R3, R6, R7, R1, R2, R14, R5, R4, R6  
1   1/4 Watt 1% Resistor   10K   R11  
1   1/4 Watt 1% Resistor   1K   R12  
1   1/4 Watt 1% Resistor   20K   R15  
1   1/4 Watt 1% Resistor   4.7Meg   R13  
1   CD40106 Hex Inverter   CD40106   IC1-A, IC1-B, IC1-C, IC1-D, IC1-E, IC1-F, IC1-C  
1   CD4013 Dual D Flip Flop   CD4013   IC2-A, IC2-B  
1   CD4066 Quad Analog SW   CD4066   IC3-C, IC3-A, IC3-B, IC3-D  
3   Ceramic Capacitor(s)   0.001uF   C1, C2, C3  
2   Ceramic Capacitor(s)   0.1uF   C6, C7  
1   Ceramic Capacitor   200pF   C5  
1   Electrolytic Capacitor   10uF   C4  
1   Operational Amplifier   TL084   IC4-A, IC4-B, IC4-C, IC4-D  
3   Phone Jack(s)   1/4" Jack   J1, J2, J3  
2   Potentiometer(s)   100K   R16, R17  
3   Potentiometer(s)   1Meg   R10, R8, R9  
9   Silicon Diode(s)   1N914   CR2, CR1, CR3, CR5, CR6, CR7, CR8, CR9, CR4, CR5, CR6