inventing the "poor man's easy ADSR"

[beep]

The ultimate low cost battery powered DIY synth still needs proper
envelope generators to compete with the moogs and arps, there are
quite a few out there but I didn't like them because of their transistors,
so I used the passive AR envelope from this thread as starting point:

http://electro-music.com/forum/topic-23960.html

I ended up with a work in progress approach to activate the decay
phase via a comparator and a 4066 switch resulting in an aprupt "off"
which will be smoothed by a decay lowpass then, letting go down all to 0v
but being mixed with the pre 4066 sustain voltage which is still up
(voltage divider pot to ground will determine sustain level)

decay to 0v and adjustable sustain voltage will then be mixed into
another buffer running into another 4066, which is controlled by the
unfiltered gate signal. after key release voltage will apruptly drop to 0v
due to 4066 open ... another lowpass will determine release time.

voila.

here is the link to the simulation. you can play around with the
circuit right now.


still having to fix some bugs because of stupid mistakes I made
but it's gonna work and it will be quite simple and even for beginners
to understand how the circuit works. I love those integrated circuit
building blocks because you do not have to hazzle with transistors and
building a synthesizer is a little bit more like building a patch on a
modular synth

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[Cfish]

Have you built this up yet? I'm looking for a basic ADSR to replace my AR in my home brew synth.

[gabbagabi]

Hello Beep,

i did not really understand your circuit,
but by checking your simu i saw that the opamps has different supply voltages.

You are describing that you are using two different Low Passes,
i did a simulation based on that (last schemo) in my thread:
http://electro-music.com/forum/post-417836.html#417836

plus some other envelope ideas.
may you have a look?

cheers
gabbagabi

[beep]

Hello!

I admit, my circuit is extremely unfinished. My goal was to avoid transistors
(cause I'm always afraid to burn them, but your circuit looks promising, since
it's single supply and involves only one transistor. I'm gonna give it a try.

I didn't even breadboard my circuit, it was just a little fiddling around
with the simulator forgot to set up all opamps' supply.

In the meantime I was working on a 40106 based super simple
single supply low parts count "quasi arp odyssey" dual vco,
which is basically based on the "single op amp saw vco" thread,
but the one-tranni-expo circuit by Kassu loses the correct tracking
completely with temperature changes.