Interesting Arbitrary Waveform Design Idea

[JKowalski]

Cloudscape's arbitrary waveform trem he posted earlier got me thinking about interesting oscillator ideas. I love the idea of being able to create your own waveforms, but the fact that you don't know what it looks like after you create it and the inability to edit in real time kind of irks me. And - coding is not something for me.

So I hit upon this idea: Have a line of adjustable sliders to draw out the waveform. Everyone has messed around with an eq before - maybe created little "waves" on the sliders. If you make each slider a voltage divider, and then switch between the slider outputs in sequence, you'll get a (albeit super blocky) waveform that replicates the slider positions. This would give you the ability to edit the full waveform in realtime, and see it visually as well.

Now - After a little bit of researching, I figured I could do the sequencing like so:

adjustable frequency square oscillator
TO
frequency divider (the 24 stage ones that let you take consecutive division outputs, ill be taking three outs)
TO
8 input multiplexer (controlled by the three divider outs)
TO
8 multiplexer-controlled analog switches (each input being the sliders)

So that should give me a sequential output of all the eight sliders, right? I'm fairly sure this will all work out, correct me if I am wrong. I might even up it to a higher number for a better, higher sample control of the waveform.

So my questions:

1. Does anyone know of another, easier way to sequence analog signals like this?
2. How can I smooth out the waveform? Is there even any way to accomplish this? This is what I am really worried about, as I recall (from my endless searching) that morphing waves (E.X. a tri to sine) is VERY difficult.


And I found those really really neat special sliders (by alpha, i think?) that have the LED's on the tips of the handles. It would be awesome visually to sync those leds with the sequencer!

[JKowalski]

Wow! I guess RG already thought of this, and he did with with less ICs.

http://www.geofex.com/Article_Folders/LFOs/psuedorandom.htm#An%20Analog%20Sequenced%20LFO

I think I'm gonna make something out of this.

[Taylor]

How does this differ from the Vanishing Point?

Slew (smoothing between steps) can be added to the VP by plugging the control signal into this:

http://i210.photobucket.com/albums/bb292/frequencycentral/slew.jpg

[~arph]

And I found those really really neat special sliders (by alpha, i think?) that have the LED's on the tips of the handles. It would be awesome visually to sync those leds with the sequencer!

That alone demands a build 
Any linkies?

[JKowalski]

http://mouser.com/Search/Refine.aspx?N=254362&Keyword=LED

Expensive, but cool anyways.

I'll check out the "vanishing point" later today. I suppose im not very original, after all   

[~arph]

Here's the one I did:



It still needs some work. (I finished it three years ago..)  The ultrabright leds eat to much current for the vactrol to have its optimal range.

[JKowalski]

That is an beautiful pedal, arph.

I checked out the VP - definitely the same concept. Regardless, I want to make it. I'll take simpler 8-to-1 switch IC that the VP used (didnt even know those existed!) and make a full featured LFO waveshaper, maybe throw in a trem and vibrato to it's output.

It's hard to think of new ideas! I was so excited... 


Taylor, do you know how effective that circuit is in smoothing the wave out? Thanks for the link!

[Taylor]

I don't, because I haven't made the VP yet. I actually just now sat down to put it together. I should be able to tell you in the next couple days if it works.