[WIP] Shifty Shaper

Forum DIY
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This project is about “upgrading” the Cadet VCO with more waveforms.
However, this will be done with Lunetta style Shift Registers, Counters and R2R ladders,
so the waveshapes are stepped. With filter switches these can be somewhat “smoothed”
The idea is to have alternative Horizontal waveshapes to use for modulating Vertical VCOs

Features:

  • Input (can be any 0-1v VCO output) → comparator
  • Shaper outputs: staircase Ramp / Triangle / Saw / Chaos
  • Switchable filters for each output
  • Comparator Squarewave output
  • Patch header for weird waveshapes (Chaos)
  • CMOS based, so expect rough shapes

Project stage: breadboarding & using the VEB2 (video experiment board) to test each design block. Schematic design is halfway done

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10 Likes
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Nice. I’m interested in how this works out.

Are you planning to have multiple simultaneous shaped outputs per input? Or is it going to be just one output that can be set to shape a variety of ways?

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Oh wow, looks like something I’d see from an Ian Fritz circuit (ie, Wavolver)

last night I had fever dreams about a vide-rate tri to sine converter…
I think this came about because when I struggle to sleep I try and “meditate” by picturing a perfectly clean circle in my head - it’s hard enough that I fall asleep doing so :grimacing: (and hard in video synths too!)

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I was thinking to have 1 input and several outputs

@Rik_bS : this shaper won’t be high quality (as the Wavolver), but lo-res on purpose

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Looks great, I will be following your progress :slight_smile:

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progress report:

I need to figure out how to sync the divider so that the output does not scroll.
maybe that trick with dividing the H or V pulse will work

For now I’m going to finish some other projects first, then continue with this one.

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Depending on how you’re dividing, your IC may have a reset pin at your disposal. Are you using a flip flop?
EDIT:
I zoomed in to your photo above. Is that a CD4040? What are you doing with the reset pin and what are you clocking it with?

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yes, a 4040. it can also be a 4013, alternatively
trigger is a vco squarewave (or any wave through a simple comparator.

I was wondering if I could use the sync pulses directly or if I need to amplify them.
(not sure if they are 1v or 5v)

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The Cadet I guide shows that the 14-pin connector uses 5V signals while the front 3.5mm jacks and 16-pin bus are both 1V. You may want to use the 14-pin connector’s signals through a 74hc14 either once or twice depending on what polarity the signals need to be for the CD40xx.

I would also like to suggest a three-way switch that syncs the reset pin to H-sync, V-sync or none for scrolling.

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thanks, I’ll try that!

maybe I’ll do H-sync/V-sync/external input on the frontpanel, because without sync the scrolling was way too fast

1 Like