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Automatic Expression Pedal and Pitchfork

Discussion in 'Effects [BG]' started by alfonso_bundis, Jul 8, 2017.

  1. alfonso_bundis


    Nov 13, 2011
    I made an "auto-expression" pedal using a 555 based flashing LED and a photo resistor. I normally use it to control the feedback loop of my bypass strip. Here is a demo with the Electro-Harmonix Pitchfork.


  2. Driven Crane

    Driven Crane

    May 30, 2014
    Super Idea!
    alfonso_bundis likes this.
  3. THat'S Super Freq'n COOL!
    alfonso_bundis and Veldar like this.
  4. alfonso_bundis


    Nov 13, 2011
    Thank you guys, here is another clip with the same setup plus an ebow
  5. That made my cat's ears perk up!

    So did you fab this pedal up using vero, perf or PCB?
    Are you willing to share your layout? If not, no worries, would be a great learning experience to try and figure it out myself; I need to embrace the "DIY" side of pedal-building more!
  6. alfonso_bundis


    Nov 13, 2011

    No problem with sharing the layout, as long as you share the results ;). I don't have many pedals with an expression input so I am really curious on how would other pedals react with auto-expression.
    The circuit is really simple, I don't have a layout yet but it consists of three parts: A momentary footswitch for activation, a photoresistor connected in series to a B250k pot wired as a variable resistor and a flashing LED. The layout for the latter can be found here: http://www.mikmo.dk/cblfo.html
    I replaced R1 with a B250k pot in series with a 1k5 resistor and used a B100k+1k5 resistor for R2.

    If you have any questions I would be glad to help. Let me know how it goes!!
  7. @alfonso_bundis

    COOL! I'm in the middle of building a Parasit Studio Flash Filter Fuzz Deluxe; I'll try your Auto-expression after that if... if the Flash works. So far, I've made a few circuits, they all work — until I box 'em up and then something magic (Bad Juju type) happens and the effect doesn't work.

    I noted in another thread I've never plugged an expression pedal into my Elements, this Auto-Express may be just the thing ...

    Clean — Distorted — Clean — Distorted — Clean — Distorted — Clean — Distorted — Clean — Distorted — Clean — Distorted — Clean — Distorted — Clean — Distorted — Clean — Distorted — Clean — Distorted — Clean — Distorted — Clean — Distorted — Clean — Distorted — Clean...

    And I've got two expression inputs on my Cosmichorus, one on my Tremolemonessence, two on the Diamond Vibrato...

    I might need to make a couple of these.

    Many thanks!
  8. alfonso_bundis


    Nov 13, 2011
    Awesome!!!! Can't wait to hear what kind of noises you can get with your pedals and auto-expression!!!
    keep me posted!!!

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