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Witches Brew V1.3.1 CV Joystick Controller

Let's you control any Voltage Control Synthesizer parameter with a Variable Voltage Output from +8V to -8V on a Joystick or other Controller

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Based on CGS04 Joystick Controller Thanks to Kenstone for his work and stereoping for their article on DIY Offset Scaler.

Main Circuits
•1 x TL074 (DC Mixer)
•1 x TL072 (Voltage to Current LED Driver)

Features
•Clearly Labeled Sections on PCB/Schematic and low parts count for beginners.
•X and Y Axis CV for Joystick
•Panel Mounted Offset/Range Knobs X/Y Axis
•Offset Postive/Negative Voltage LED Indication
•Inverted X/Y Axis CV output

Dopfer Joystick is typically Set for +8v Max and -3v Max for practical musical use.

-Warning-
This is my first PCB and Design. Use at your own risk with off the shelf eurorack Modules. This is the first Version and works fine. But it is still A DIY Synthesizer and my modular and electrical Design skill are limited. But will be improved on over time.

PCB is made so you can stack it. So that it is open for modding you could house
2 joysticks in a arcade style Joystick Box.

V1.2.0

It worked as intended surprisingly:)

V1.3.1

Features 

•X and Y CV for Joystick or other resistive pots

•Offset/Range Panel Knobs X/Y 

•Offset Postive/Negative Voltage output LED Indication 

•Optional X/Y AXIS Inverted CV output

The Redone schematic for witches brew module. LEDs are now driven linearly. The LEDS Brightness Linearly controlled By Converting Voltage Output to Current method *So It can Accurately Display the Voltage on the LED. Also redone most of the artwork with my improved art skills.

Also going to release the PCB files once finalized and maybe do some limited runs.

Schematic_witches brew 1.3.1 Stock_2021-02-02.pdf

Removed the passive attenuation and added optional Always inverted Switch.

Adobe Portable Document Format - 89.94 kB - 02/02/2021 at 21:55

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Adobe Portable Document Format - 92.40 kB - 02/02/2021 at 21:55

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Schematic Witches Brew 1.3.0.pdf

The Redone schematic for witches brew module. LEDs are now driven linearly. The LEDS Brightness Linearly controlled By Converting Voltage Output to Current method *So It can Accurately Display the Voltage on the LED.

Adobe Portable Document Format - 91.68 kB - 10/30/2020 at 20:20

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Schematic Witches Brew v1.2.pdf

Old version 1 PCB Schematic

Adobe Portable Document Format - 188.39 kB - 06/27/2020 at 23:10

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ms-excel - 3.14 kB - 06/27/2020 at 23:01

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  • 1 × Tl074 Amplifier and Linear ICs / Operational Amplifiers
  • 1 × Tl072 Amplifier and Linear ICs / Operational Amplifiers

  • 1.3.1 (Optional) Always Inverted Switch

    Neil Mundt02/07/2021 at 22:14 0 comments

    There in v1.3.1 there is a option to add a always inverted switch. So this simple mod you can add it if you want. 

    The first Inverted output version, I tired the idea with a separate Inverted CV Jack. 

    But as someone pointed out that the way the circuit works if you tweak of offset knob it wont just effect the the first CV jack with the offset knob, but also effect the Inverted output switching polarity too which kind of defeats the  propose of it being a always Inverted Output.   

     I am looking into designing one that has a Always Inverted CV output. But it would require more work to function properly and a full redesign with 2xTL074.  Tomas Henry MFOS Quad DC Modulation Mixer has something very Similar  and is a interesting read if you want to learn about Op amp Mixers.   

  • From Protoype to Version 1.3.1

    Neil Mundt02/02/2021 at 23:05 0 comments

    I have to say looking back on the first PCB layouts. My skills have a quite a bit of improvement Between versions of PCB  layout. In Planning out sections of the board and optimizing placement of components. Quite a bit of things you should plan out before even thinking about doing the traces. 

    My first designs were so Simple the autoroute worked perfectly fine. But soon as I added complexity too the placement it would eventually give up on completely routing. I brushed up on manual routing and common good practices. I found the use of a auto router is a good base for starting manual routing. Then doing manually is just like putting a puzzle together. 
    I also learned about using Copper infill and Ground planes for the Double sided PCB and why it cleans up quite a bit of the grounds and +12v Rail. Before using these Manual routing started to become a nightmare becoming quite the rats nest of wires.   

  • Witches Brew 1.3.1 PCB With Optional Inverted Output

    Neil Mundt12/28/2020 at 23:04 0 comments

    I cleaned up the rats nest of traces. It seems it went quicker. Now have more experience with Easy EDA.

    •Added a +12v copper infill on the Top Layer for the Power rail too clean it up a bit.

    •Removed the Passive Attenuator, Because of testing I found it pretty redundant with already having a range knob. No need to complicate things.

  • Witches Brew 1.3.1

    Neil Mundt12/14/2020 at 01:17 0 comments

    After further use of the Witches Brew.  I decided that the passive attenuator section is pretty redundant with the range knob. No point in having it making things more complicated and take more time too build. I am also adding the Option to have a Inverted X/Y output. Too add more flexibility too the module.  Things have been Slow, But it shouldn't take long too redo the PCB. This is a great article about Offset Scalers. I found this when Modular in a week introduced me too that page and was a interesting feature too add. 

  • Quick Demo of the Witches Brewstick

    Neil Mundt11/01/2020 at 00:00 0 comments

    For anyone interested, This is a video demo of LMNC AD/AR module and a patch with my system controlled by the witches Brew module. I would like to thank LMNC for giving the community projects some spotlight. Kosmo System Project Feat. Witches Brew Control voltage Joystick

  • V1.3.0 PCB Design

    Neil Mundt10/30/2020 at 20:56 0 comments

    After doing the PCB Layout and redoing some of the Artwork. I present you a very close Representation of what a final PCB will look like. I would like too thank Kristian Blåsol for his series Modular in a week for teaching me and pointing me in the right direction. 

    Also LOOKMUMNOCOMPUTER for teaching how to motivate myself and not get down when things don't work as planned "Don't be afraid to try it." Been Though so many failed circuits and Burned IC's. But was able to make something out of it. 

  • V 1.3 Redoing the LED Driver Circuit so it is properly Linear.

    Neil Mundt10/23/2020 at 03:14 0 comments

    So after some testing and Reading other methods of driving LEDs. I decided on Converting the output voltage to Current Source. That it would be the best way to Linearly display the output voltage. While my original idea did work to drive the LEDs they would Cut to zero Brightness(Lumis) still at 500mv output. That is because controlling it by voltage cannot be completely linear Due to the LED forward voltage. Now that I am controlling them by current we are actually able to accurately Display the voltage on a Blue and Red LED. Now that I solved that problem. I'll Re Design the PCB too incorporate these changes. It was pretty fun finding a fix for this.

  • 1.2.5 Revision/Beyond

    Neil Mundt09/05/2020 at 03:03 0 comments

    *Pcb fully functional as intended

    I will revisit this project later. I'll make some fixes on the PCB  and Release the PCB Layout.

    If I do Redo the LED driver and add some more features. I might sell some PCBS after that, But as it stands for now. I Personally Don't feel like I have changed too much from the original CGS Joystick Controller Design.

    ----Problems----

    -Hard to solder onto ground plane due too thermal conductivity of ground plane(Noobie's Bewares) 

    -Fix PCB LED layout (switch X and Y axis with each other)

    -Fix PCB LED and capacitor foot print too more spacious

    -FIX PCB Layout (add OFFSET panel Control too PCB Mask layer)

    --Fixes--

    -Find Stand offs with proper clearance in metal variant(only pvc ones have proper hight for proper stacking.

    -add diodes or some ability to prevent LEDS from getting lfo or oscillator signal effecting LEDs brightness 

    Later Revisions Features

    -Redo LED driver circuit so it is current controller making the led incantation linear (Doesn't Cut too 0 Brightness at 500mv)

    -Add optional always inverted output header

    -Add +/-8v LED Digital Display Voltmeter 

    Red for +Positive voltage 

    Blue for -Negative voltage

    I would Like too. Thank Kristian Blåsol for the mention on his channel. He has a great series called modular in a week with great projects. Learned Quite a bit from his videos here is  His Video On CV controllers/Joysticks

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