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Open Arduino Sequencer project
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mrkva



Joined: Jan 25, 2012
Posts: 41
Location: poland/slovakia/netherlands

PostPosted: Wed Jan 25, 2012 7:54 pm    Post subject: Open Arduino Sequencer project Reply with quote  Mark this post and the followings unread

Hi guys,

I've been researching on topic of arduino sequencer for a while and inspired by it all I decided to create 'open' version available for everyone, with schematic and nice design Smile.
Main advantages should be:
* controllable from computer (steps, not values) or standalone
* CV range (0-10V) for modular synths
* very fast - usable as wavetable synth
* since its arduino, should be programmable in interesting ways (more advanced random for example)

Here is what I got so far (first schematic I ever did): http://i.imgur.com/USaSj.png

As you see its very primitive. I use 4066 as switches controlled by arduino digital pins. I trigger one after another, therefore connect the pots to the output and get values.

However I ran into some problems I hope you guys might help me with.
First: I cannot get the amplification right. Is the way on the schematic correct?
Second: How about power supply? I understand that for opamp to amplify to 10V (from max 5) I need to have 10+V at its supply. Is that correct? Does this need to be symmetrical? That would make the whole project kind of awful to travel with. Ideally I would love to have it battery powered.


Thank you very much for any advices. I can share also the arduino code, but its not very important at this point.
Jonas
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Fri Jan 27, 2012 8:48 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi -

There are some problems you'll need to solve to make this work.

The main thing is that the Arduino wants to deal with 5V and Grnd level signals, but you're trying to control 10V signals. Unless you put in some sort of level translation between the Arduino and the analog switches, I don't think this is going to work.

I'm at my day job right now, so can't spend a lot of time - I'll try to get back to you later with more details.

You might want to check around on the Arduino websites to get some more info on level translation....
Gary
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mrkva



Joined: Jan 25, 2012
Posts: 41
Location: poland/slovakia/netherlands

PostPosted: Sat Feb 04, 2012 7:20 am    Post subject: Reply with quote  Mark this post and the followings unread

Mongo1 wrote:
Hi -

There are some problems you'll need to solve to make this work.

The main thing is that the Arduino wants to deal with 5V and Grnd level signals, but you're trying to control 10V signals. Unless you put in some sort of level translation between the Arduino and the analog switches, I don't think this is going to work.

I'm at my day job right now, so can't spend a lot of time - I'll try to get back to you later with more details.

You might want to check around on the Arduino websites to get some more info on level translation....
Gary


Hey man, thanks for answering. I've already figured it out. The 5V to 10V part is done trough the op amp in the schematic, but I had problems with its power supply. In the end I've found out that it was just not getting enough juice for the gain of 2, so I used two batteries in the end.
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