ADSR for Eurorack derived from Elektor Formant

[Haralds:Werk]

This is another derivation off the ADSR from my NGF_E project, adapted to 12V Euro-rack format. Because this one is a stand alone module I have removed all additional features from the Next Generation Formant project. Nonetheless it is still based on original Elektor Formant ADSR schematic. I made some error corrections and added my changes to the design. All parts are updated to today (2021/01) available parts. I have made a few changes to fix some shortcomings of the original. A triple range switch was added for finer adjustment of the ADSR CV-output signal. The attack rise time is shorter now as in the original. The gate input is buffered. The fixes a fault in the original when working with analog sequencers. The output voltage is slightly raised to reach really 5V. Due to the design of the original Elektor Formant ADSR the output of the original ADSR keeps a residual voltage of about 0,5V. I have put an compensation in my design to correct this. The driver circuitry for the output indicator LED is changed for better linearity.

Specs and features
• AD/ADSR switch
• Gate input 5V
• CV output ..5V
• CV output indicator
• Range switch: fast, middle, long
• Attack (A) 0,5ms...16s
• Decay (D) 4ms...40s
• Sustain (S) 0..5V
• Release (R) 4ms..40s
• Power consumption below 15mA each rail

The documentation and the Gerber files for download can be found in my website.

[dot matrix madness]

Nice to have a really working, simple AD/ADSR design.

[Haralds:Werk]

Nice to have a really working, simple AD/ADSR design.

Thank you. Here are some screenshots.

SCR01.PNG (7.23 KiB) Viewed 190 times

SCR02.PNG (7.33 KiB) Viewed 190 times

SCR03.PNG (7.26 KiB) Viewed 190 times

SCR04.PNG (7.5 KiB) Viewed 190 times

SCR05.PNG (7.67 KiB) Viewed 190 times

[Quinie]

Gerbers for panel (untested)

[Kelaifu]

another beauty! I think this will be headed to my rack too. Excellent work as always and thanks to Quinie for the usual panel...When I opened the thread I thought to myself 'I hope Quinie has made a panel...' are there it is!

[Quinie]

All credits go to Harald.

My part is just taking his FPD file and 15 minutes of my time. I made a "manual" https://www.quinie.nl/making-panels-in-kicad-from-dxf/ on my site if you want to do it yourself or change parts of it, without any knowlege it will take you about a hour (I think).

Putting in a little more effort the panel can even be made more beatifull.

I try to do some PCB design myself and can only imagetion how many hours/days Harald put into this. And sharing to us, makes him a legend in my book. Can't believe how big my rack became these last months, thx Harald!!

[Quinie]

Most parts came in the mail today. Still waiting on the pots. Pots seem to be short everywhere. I might have a few left to finish one of these boards.
Just a two questions for the ADSR build

- SW1 = on/on, SW2 on/off/on ?
- the pictures show unpolarized caps (c2,c3,c4) or should i put my glasses on?

edit: extra question..

The panel seems to fit. But my switches don't fit the holes in the front pcb. It seems the footprint matches but the pins of the switch are bigger.
Did I get the wrong part?

[Haralds:Werk]

Most parts came in the mail today. Still waiting on the pots. Pots seem to be short everywhere. I might have a few left to finish one of these boards.
Just a two questions for the ADSR build

- SW1 = on/on, SW2 on/off/on ?

Yes

- the pictures show unpolarized caps (c2,c3,c4) or should i put my glasses on?

Those are Tantalum caps, which are polarized. They have different length legs and a small + signs on the side. Not visible on the picture.

edit: extra question..

The panel seems to fit. But my switches don't fit the holes in the front pcb. It seems the footprint matches but the pins of the switch are bigger.
Did I get the wrong part?

As far as I can see from the picture you have bought switches with solder lugs for wires. Do the have a whole in the solder lug? Then they won't fit. You need switches for through whole mounting.

[Haralds:Werk]

Switches like this:

https://de.rs-online.com/web/p/kippschalter/0401670/

THis is the on off on swithc i use