Capacitor choice for good result

m4vrick
New Member

Posts: 45

Capacitor choice for good result Jul 21, 2021 8:58:07 GMT admin and maydonpoliris like this

Quote

Post by m4vrick on Jul 21, 2021 8:58:07 GMT

Hi all

This is my first question here, hopefully not my last one as I planned to make several modules by myself

The first module I'll build is an adaptation of this project : note.com/solder_state/n/n30b3a8737b1e
It's based on an Arduino board and the mozzi library.

I'm rebuilding it from scratch to keep only the µC on the board and going to full SMD.

My question is about choosing the right type of capacitor for the audio part, mainly the output circuit:
- 2 capacitor (22nF and 10nF) for the low pass filter
- 1 capacitor 4.7µF for the AC coupling (as I understand the schematic)

Is there any recommandation about the type of capacitor ? type of dielectric ?
Or can I go for all purpose X7R ones ?

thanks for you help

--== M4vr|ck ==--

robertlanger
Administrator

Posts: 605

Capacitor choice for good result Jul 21, 2021 10:26:27 GMT

Quote

Post by robertlanger on Jul 21, 2021 10:26:27 GMT

The stuff of this guy is great! I discovered it a short while ago and it gave me some inspiration - great you want to make the additive oscillator!
The output filter with 22n and 10n looks fine; together with the 3.9k it's two lowpass filters with approx 2000Hz and 4000Hz cutoff - seems fine especially for this application.
The output capacitor is not necessary in the AE world, because the output signal of the opamp will be centered at 2.5 volts anyway which is the "audio center level" for AE. Also the clamp diodes at the output and several CV inputs can be omitted for AE, because everything happens within 0...5 volts.

Capacitors: Simply use all-purpose ones.

I'm supoer curious to see and hear it in action; please keep us updated!

Last Edit: Jul 21, 2021 10:27:58 GMT by robertlanger

m4vrick
New Member

Posts: 45

Capacitor choice for good result Jul 21, 2021 10:47:12 GMT admin and keurslagerkurt like this

Quote

Post by m4vrick on Jul 21, 2021 10:47:12 GMT

Wow, first post and reply from Robert

Thanks for your help, analog electronics is far from being my major skill ^^
I was curious about the AC coupling output and the clamp diodes adaptation for the 0-5V range for AE, will be much easier to build without it.
That's why I really love the AE modular format, it keeps everything simple regarding the different signals.

I'm building at least 3 of them, one for me and one for a friend who is already here, Moruial. I planned to make only DIY module except for the master module he gave me.

Of course I'll keep you updated. Maybe I could start a dedicated topic on this build ?

Thanks for all your help and work you putting on this project

--== M4vr|ck ==--