===== PS411 EnvAmp (Attack/Release Envelope Generator & Opto-VCA)=====
by Antti Pussinen\\
The Dynamics of synthesized sounds are controlled with a Voltage Controlled Amplifier, or VCA.
In a classical subtractive synthesizer arrangement the VCA is controlled through an envelope generator, allowing more interesting dynamic possibilities than just the on/off of a note gate.
{{:paper_synth:ps411_envamp_1200_3999.jpg?600|}}\\
Vactrol based Opto-VCA add an Attack and Release time automatically due to the relatively slow turn on, and off times of the led-ldr pair inside a vactrol. The ”opto” part of our VCA is a fast and accurate AC-Optocoupler, which adds a tiny bit of Attack time and Release tail to the signal, but not so much as a Vactrol would. We Decided to go with the optocoupler since factory made Vactrols are getting more rare and expensive, and altho rolling your own is a good choice, the response varies due to led and ldr types and manufacture tolerances.
The Paper Synthesizer PS411 adds more control to the opto-VCA with Attack and Release control potentiometers. If both turned to zero, the module acts like a normal VCA, controlled by external CV.
If Attack or Release are adjusted, it affects the input CV before it controls the VCA. If CV input is a Gate signal, the envelope generator works like a normal Attack Release generator. Created envelope can be used to also control other modules view envelope output connector. A led is used to visualize the envelope. A jumper in the board selects between long and short attack and release ranges.
The module comes also with an bipolar offset potentiometer for manually controlling the amplitude.
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====Scope====
{{:paper_synth:ps411_scope_pic.jpg?400|}}\\
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==== Schematic ====
{{:paper_synth:ps411-origami_envamp_1200.jpg?400|}}\\
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==== Paper PCB ====
{{:paper_synth:ps411_envamp_10.jpg?400|}}\\
{{ :paper_synth:ps411_envamp_10.zip|}}\\
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==== Faceplate ====
{{:paper_synth:ps411_envamp_faceplate_11.jpg?200|}}\\
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==== Parts ====
* **Resistors:**
* 1x 68 Ohm
* 1x 100 Ohm
* 3x 1 kOhm
* 2x 10 kOhm
* 1x 1.5 kOhm
* 1x 5.6kOhm
* 5x 100 kOhm
* 2x 470kOhm
* **Capacitors:**
* 1x 22µF (bipolar)
* **Diodes:**
* 5x 1N4148
* 1x LED
* **Semiconductors**
* 1x TL072 OpAmp
* 1x TL074 OpAmp
* 1x H11F1 Optocoupler
* **Mechanical:**
* 1x IC socket, 8pins
* 1x IC socket, 16pins
* 1x IC socket, 6pins
* 4x Thonkiconn 3.5mm jack socket
* 1x pin strip 2x8
* **Trimmpotentiometer:**
* 1x 50 k
* **Potentiometers:**
* 2x 100k lin
* 1x 100k log
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==== License ====
The PS411 EnvAmp was designed by **Antti Pussinen** 2017.\\
It is licensed under a [[http://creativecommons.org/licenses/by-nc-sa/4.0/"|Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License]].
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