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 Forum index » DIY Hardware and Software » Microcontrollers and Programmable Logic
Arduino-based Octature / VC polyphasic LFO.
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reve



Joined: Feb 23, 2008
Posts: 147
Location: USA

PostPosted: Mon Apr 16, 2012 12:30 am    Post subject: Arduino-based Octature / VC polyphasic LFO. Reply with quote  Mark this post and the followings unread

Note: videos crossposted at Muff's.

Hey guys. You know how I was talking about the Polyphonic EG here? I decided to start off with something easier. On the upside, this one's already working as intended. Wink

So you know how a quadrature oscillator has four outputs 90 degrees out of phase to each other? The octature oscillator has eight outputs, each of which is 45 degrees out of phase to the others. UNLESS you flip the magic switch, then you control the degree (heh) of phase offset between each oscillator between 0 to 90 degrees.

Here's a couple videos that better illustrate the concept:

First some oscilloscope action. These are outputs 1 (0 degrees) and 8 (315 degrees offset in octature mode). As we go vc phase you'll see output 8 go from 0 degrees out of phase to 630 degrees out of phase. In this video you also see the "aliasing" at the end as I crank the phase knob fast. That may go away with adequate output filtering, though.
http://youtu.be/lLMp0uQZ85I

Second, we have the module controlling LEDs with a little narration. Seeing it beats me trying to type it. You don't see the full effect because we're going from 0-5v to light up LEDs instead of -5 to 5v, but you should get the idea.
http://youtu.be/lO06MTuQIM8

Analog section needs development? Wanna lend a hand? Or if you're interested in helping on the software side the code's at:

https://github.com/rmosquito/PolyLmFaO

... lemme know and I'll get you commit access?

Cheers!

_________________
- r. mosquito
SynthDIY Synthpop -> http://www.reverbnation.com/photovoltaik
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