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Thread: organ foot pedal MIDI controller- switch ideas?

  1. #1

    organ foot pedal MIDI controller- switch ideas?

    I built a midi controller using a 50s hammond 12 key foot keyboard. However the factory switches used these plastic pushers and after 60 years the plastic is breaking down and many of the switches no longer engage. I am taking it as an opportunity to shed 5 or 6 pounds and a bunch of lead solder by loosing the entire switch assembly

    Im seeking advice / opinions on what I should use for switches. Im thinking the easiest thing would be getting some panel-mount momentary switches and mounting them on a bar so they get pressed when the key goes down. But then I was thinking about the pressure switches so I could do something with key-specific volume. ideas? cost is a factor...

    Thanks

  2. #2
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    I've stripped a range of organs for the optical expression pedals and a Hammond (80's) foot keyboard duly connected to a Teensy LC. I've noted that some more "modern" (80's) organs may have multiple switch contacts on the foot keyboards making it relatively easy to do Velocity sense. Food for thought?

  3. #3
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    I've worked on an organ that used a cylindrical magnet in the end of each pedal and a reed switch would close a contact when the pedal was depressed. Here is one idea; http://www.musanim.com/mam/organproject.html

  4. #4
    I was able to do velocity sensitive on the hammond. It had a global switch that engaged before the switches on the keys. I hated it just because the difference in the keys felt like I was getting random volumes. I probably could have tamed it but instead I just turned it off. but I am intrigued by the idea of a pressure switch where i could alter the volume of a note as it was being played by going in harder or letting up.

  5. #5
    Member ETMoody3's Avatar
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    I use the widely available infrared switches often used on 3D printers... buy spares because there're not the best made things... I have a 17 key midi pedalboard I hand built that works reliably and Ive used it in live performance.

    The neat trick is that you can put one of those and a regular LED / photoresistor together on the same pedal key where the IR triggers the on/off state and the visible light / photresistor pair gives you velocity, using a slotted gate.

    Noteworthy that while I did the velocity trick on the bench, my footwork isn't so swift that I wanted velocity sensitive pedals, so they're on/off only.

    I use the visible light gate trick to make expression pedals. There's 10 of them above my key pedals. Pics coming...

  6. #6
    Quote Originally Posted by ETMoody3 View Post
    I use the widely available infrared switches often used on 3D printers... buy spares because there're not the best made things... I have a 17 key midi pedalboard I hand built that works reliably and Ive used it in live performance.

    The neat trick is that you can put one of those and a regular LED / photoresistor together on the same pedal key where the IR triggers the on/off state and the visible light / photresistor pair gives you velocity, using a slotted gate.

    Noteworthy that while I did the velocity trick on the bench, my footwork isn't so swift that I wanted velocity sensitive pedals, so they're on/off only.

    I use the visible light gate trick to make expression pedals. There's 10 of them above my key pedals. Pics coming...
    Very interesting!
    I barely understood how the led/photoresistor thing works for velocity, but looks like a brilliant idea... can you explain more about it?

    Thans

    Stefano

  7. #7
    Member ETMoody3's Avatar
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    I took apart the bench test rig two years ago... should've taken pictures.

    The photoresistor gives you an analog signal to read with your microcontroller. I was going to use a bunch of atttiny85 configured as I2C slaves.

    Here's a terrible sketch of how an optical gate might work on an organ pedal.

    Click image for larger version. 

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    Here's pics of the non velocity rig

    Click image for larger version. 

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    Click image for larger version. 

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    And a little detail of the gates attached to the expression pedals, although you can't see the business end. The aluminum parts are epoxied to the wood

    Click image for larger version. 

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    The neat part is that the visible light doesn't interfere with the IR switch and vice versa. You're on your own figuring out how to isolate each key pedal from the next. I was going to use simple black cardstock. The idea also gives you aftertouch on each key, a thing that's a little trickier with "two point" timing methods.

    Downside? Dust! Mother o gawd dust is an issue.
    Last edited by ETMoody3; 09-09-2019 at 01:53 PM.

  8. #8
    In the old days many people used to use roller ball microswitches such as these
    https://uk.rs-online.com/web/p/microswitches/1854073/

    They are break before make so you can time between them and calculate the velocity.

  9. #9
    Member ETMoody3's Avatar
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    Forgot to mention... velocity is derived from a simple timing factor, triggered by the IR switch. The analog input gets read a set amount of time afterwards and you create a velocity amount based on that. I.e. 25 milliseconds after, if the analog reads highest or lowest ( doesn't matter which way you wire it, pick one ) then your velocity is maximum. This is of course an arbitrary example, you'd have to experiment to find figures that work for your playing. Then, the next line of code after deriving the velocity, you can have the analog value translate into after touch.

  10. #10
    Quote Originally Posted by ETMoody3 View Post
    I took apart the bench test rig two years ago... should've taken pictures.

    The photoresistor gives you an analog signal to read with your microcontroller. I was going to use a bunch of atttiny85 configured as I2C slaves.

    Here's a terrible sketch of how an optical gate might work on an organ pedal.
    [...]

    Downside? Dust! Mother o gawd dust is an issue.
    Thank you for the pictures and the explanation :-)

  11. #11
    I had a morely volume pedal from the 70s that used a photoresistor instead of a rotary potentiometer. with an incandescent appliance bulb! interesting idea but the dust thing would make calibration difficult.

    I am leaning towards some combination of the 16mm panel mount pushbutton switches and some FSR panels for the after touch. Like I said the initial velocity is not that big of a deal for me.

  12. #12
    Member ETMoody3's Avatar
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    Newer Morley uses a red LED. So does digitech and DOD, probably others. Have fun!

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