How to draw make a circle with ramps


#1

How to draw a circle with the ramps from VC or Cadet Ramps?

I know i can use the premixed ramps from VC but how to it without those. Assuming both switches on my VC are set to centre point i.e how the ramps from Cadet output, How would i go about making a circle. Im thinking this could be possible with Arch?

Mirroring for each ramp can be handled by Staircase or Arch but how to modify the ramp shape to Logarithmic and Exponential?


Getting more shapes from Visual Cortex
#2

The bottom right section of Arch creates a square (exponential) or log shape from a ramp or mirrored input.


#3

@microtonal is correct. You can transform the linear ramps into logarithmic (parabola) using the bottom right section of Arch. You’d need a log circuit each for horizontal and vertical, and then mix the results.

That’s option #1. Another is to use a multiplier function. Multiplying a ramp by itself (mult to source and CV inputs of a fader or other gain control circuit) will produce an exponential curve. If you subtract the exponential curve from the original signal at 2X gain, you can get a logarithmic curve. This patch is possible with the right hand sections of Bridge (use the fader section to do the power of 2 multiply, and the mixer section with some multing to combine 2X original signal - fader output.)

And of course option #3 is the Shapechanger module, which has a dual gamma shaping circuit that morphs from exponential to linear to log on both horizontal & vertical channels.


#4

Could you give some more patch notes on this. Im having a try but getting something wrong.


#5

Here is what i have so far. Ive made the first part of it and it gives me some nice variations when using the VC mirroring but not quiet there.

What have i patched wrong here?

Ramps set to centre mirroring off.

No mirroring. Ramps set to centre.

H output mirrored. Ramps set to centre.

H+V Output mirrored. Ramps set to centre.


#6

Here’s the recipe to turn a triangle ramp into a parabolic ramp:

  1. H Ramp -> Multed to Bridge Fader B & Bridge Fader VC
  2. Bridge Fader Out -> Bridge Mixer - (Subtracting) Input
  3. H Ramp -> Multed to Bridge Mixer + (Adding) Input #1 & Bridge Mixer + (Adding) Input #2 (adding twice gives gain X2)
  4. Bridge Mix Out -> Parabolic Ramp

If you repeat the above steps twice (for H & V) and mix the results then you get a Circle.

If you want to move the circle around and rotate it (with Navigator) you need to use sawtooth ramps -> mirror -> parabolic shaper -> mix. You can see why I wanted to condense this workflow into a larger analog computing module! (Shapechanger, which will finally be available again soon.)


#7

Thank you for the recipe. I patched it out, tossed in a VCO with a key and now have a new avenue to explore.

LZX%20Half%20Circle%20Patch


#8

I love to see Bridge getting that loaded up all at once! Talk about making the best use out of a single utility module! Nice work!


#9

Added in a little color.