This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Monday, February 9, 2015

Hollis Flatline Optical Compressor

Here's a good, subtle sounding compressor. It uses a LDR and LED to control the limiting done by the effect. You can go the home-brew route and put a LDR and LED in some shrink tubing or there should be enough space to use a VTL5C2 or a NSL-32 photocoupler. Diodes I've listed as 1N34s but any germanium diodes should work.

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7 comments:

  1. Max SthFebruary 15, 2015 at 12:42 PM

    http://i.imgur.com/pW7gyh0l.jpg
    http://i.imgur.com/wU4w2s2l.jpg

    i use 1n60p instead of 1n34
    when i crank up the sustain it got quite fuzzy

    here is a demo
    clean signal > min. sustain > mid sustain > max. sustain
    (i keep my volume at max)

    https://soundcloud.com/dieppl-1/compressor-demo

    ReplyDelete
  2. dtgehringFebruary 15, 2015 at 7:14 PM

    Check out Mirosol's comments on lvlark's layout over on the Tagboard Effects blog.

    http://tagboardeffects.blogspot.com/2012/02/john-hollis-flatline-compressor.html

    He changed the sustain pot to 50k with a parallel resistor to get it up to around 75k to remove the distortion when its maxed. Hope that helps.

    ReplyDelete
  3. Evan GoldsboroughJanuary 22, 2018 at 9:05 PM

    I built this and it's working great, but it requires too much input before it begins to compress. Does anyone have an idea of how to tweak this pedal for lower input volumes

    ReplyDelete
  4. Evan GoldsboroughJanuary 28, 2018 at 3:54 PM

    For anyone who had the same question: 47k resistor can be replaced with a pot

    ReplyDelete
  5. FireproofAugust 28, 2019 at 1:08 PM

    Hi, LDR 5mm 5K-0.5Mohms 150v can work? with what led? 3 or 5mm and what color? tnks!

    ReplyDelete

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