Trapezoid quadrature through zero VCO (Euro version) with waveshapers

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Haralds:Werk
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Trapezoid quadrature through zero VCO (Euro version) with waveshapers

Post by Haralds:Werk » Thu Feb 11, 2021 8:01 am

This is my third take on the Trapezoid VCO core designed by Don Tillman. My first implementation for a 15V banana system with separate waveshaper can be found here. My second implementation for a 15V banana system with integrated waveshaper can be found here.This time I moved on to the 12V Eurorack format. The core is still based on the original design from Don (used with permission). I found the original article and schematic about the Trapezoid VCO on Don Tillman's site. The article consists off three parts with the core implementation in part 2. I kept the basic idea and changed nearly everything else. I use an other exponentiator scheme and temperature stabilization. Another reference voltage device is used. A octave switch is added. And quadrature square outputs are implemented. As well as the additional waveforms triangle, sine, ramp up, ramp down and pulse.

Specs and features
• Trapezoid quadrature output
• Square quadrature output
• Triangle quadrature output
• Sine quadrature output
• Pulse output, 0deg, 90deg
• Ramp up output 0deg, 90deg
• Ramp down output 0deg, 90deg
• Octave switch
• Through zero modulation
• PWM input
• V/Oct, FM log and trough zero CV input
• Temperature compensated
• Fine frequency setting
• Runs on +/-15V and +/-12V
• Power consumption around 110mA each rail



The documentation and the Gerber files for download can be found in my website.

Only a few pictures here. Screenshots from the outputs and more on my website
Trapezoid_Euro_front.JPG
Trapezoid_Euro_PCB_095F.JPG
Trapezoid_Euro_PCB_095B.JPG
Trapezoid_Euro_back.JPG
www.haraldswerk.de
Home of Next Generation Formant

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EASYBOY
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Re: Trapezoid quadrature through zero VCO (Euro version) with waveshapers

Post by EASYBOY » Thu Feb 11, 2021 8:13 am

FIRE

this looks great.
If anybody is making a pcb please get in touch with me.

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Haralds:Werk
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Re: Trapezoid quadrature through zero VCO (Euro version) with waveshapers

Post by Haralds:Werk » Thu Feb 11, 2021 8:30 am

EASYBOY wrote:
Thu Feb 11, 2021 8:13 am
FIRE

this looks great.
If anybody is making a pcb please get in touch with me.
You can download the Gerbers for free and order them yourself. Or PM me.
www.haraldswerk.de
Home of Next Generation Formant

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Re: Trapezoid quadrature through zero VCO (Euro version) with waveshapers

Post by devinw1 » Thu Feb 11, 2021 12:08 pm

Nice one. I really want to design one and I've been knocking the idea around of Trapezoid VCOs in my head for over a year now...it's just so cool. However, I have yet been able to come up with a design that works well which isn't so much like Don T's that I'd essentially be ripping his core off. A very tricky problem indeed but very neat.

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Re: Trapezoid quadrature through zero VCO (Euro version) with waveshapers

Post by burdickjp » Thu Feb 11, 2021 2:19 pm

I don't see this on modulargrid yet. How does it get added?

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Re: Trapezoid quadrature through zero VCO (Euro version) with waveshapers

Post by Quinie » Fri Feb 12, 2021 11:15 am

Can not wait to make this one. Curious on how it's going to sound. Order the boards and made a panel out of the fpd file (see attachment).
Untested but hopefully in two weeks on my desk.
Attachments
Trapezoid_VCO_Euro_Panel.zip
(49.76 KiB) Downloaded 5 times

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Re: Trapezoid quadrature through zero VCO (Euro version) with waveshapers

Post by pierstu » Tue Feb 16, 2021 6:56 am

Hello, long time lurker, first post here.
I've had a quick email chat with Haralds:Werk and he doesnt want to answer individually, which anyone could understand.
So here are my few silly questions (might have more later):
  • At R10, is the tempco a PTC? What's OP's recommendations for ppm, series or tempco type, eventually preferred manufacturer? The only axial 2K tempcos i come across these days are these
  • Are SMD caps footprints 0805? I guess stable C0G or X7R ones, say 16V to 50V, should do it?
  • Has anyone a source for 2220s? Digikey has, but the moq is 45, and only one is required. I didnt see a clone at Alfa yet, there are some at Rochester for a fair price i guess, but it'd be cool to have more choice
    edit: moq of 45 at rochester aswell
    edit 2: Alfa has AS395, but in a tin package.
Also OP sent me his boms from Eagle so I could compare with mine, finally i uploaded it on GSheets with his permission (one tab for the front board, the other for the back one) : Euro QTZ VCo - OG values

Thanks again for making this project available !

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Re: Trapezoid quadrature through zero VCO (Euro version) with waveshapers

Post by Haralds:Werk » Sun Feb 21, 2021 6:17 am

pierstu wrote:
Tue Feb 16, 2021 6:56 am
Hello, long time lurker, first post here.
I've had a quick email chat with Haralds:Werk and he doesnt want to answer individually, which anyone could understand.
So here are my few silly questions (might have more later):
  • At R10, is the tempco a PTC? What's OP's recommendations for ppm, series or tempco type, eventually preferred manufacturer? The only axial 2K tempcos i come across these days are these
  • Are SMD caps footprints 0805? I guess stable C0G or X7R ones, say 16V to 50V, should do it?
  • Has anyone a source for 2220s? Digikey has, but the moq is 45, and only one is required. I didnt see a clone at Alfa yet, there are some at Rochester for a fair price i guess, but it'd be cool to have more choice
    edit: moq of 45 at rochester aswell
    edit 2: Alfa has AS395, but in a tin package.
Also OP sent me his boms from Eagle so I could compare with mine, finally i uploaded it on GSheets with his permission (one tab for the front board, the other for the back one) : Euro QTZ VCo - OG values

Thanks again for making this project available !
Sorry for the late answer. I did not get a notice from Muff's that there is something new on this thread.

R10 is a PTC 1% 1/6W 3300ppm Akaneohm available from Thonk. The octave rotary switch is from Thonk as well.
The SMD caps are 0805. They are between the positive and negative rail. So minimum voltage rating should be about 30V or higher.
The 2220 is available from synthcube (16USD for two) or a replacement from dslman https://www.diysynth.de/?cat=c6_aktive- ... 3_6&page=2 (4€) .

The BOM is just a raw output from eagle. No editing done.
www.haraldswerk.de
Home of Next Generation Formant

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