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.

Friday, December 19, 2014

Run Off Groove Modified EA Tremolo

Here's Run of Groove's take on the DIY classic EA Tremolo. I've laid it out so that the rate indicator LED can also be used as the on/off indicator.

Here's how you'd wire the LED to a 3PDT switch as the on/off indicator.


  1. theres a pad missing on the pcb between the 2m2 and 1uf cap

  2. ive finished it, volume can be a trimmer unless you like the option of having a massive volume boost availlable, rate might be better as a linear as the speed is pretty bunched up.
    otherwise it sounds pretty close to my princeton reverb trem.
    nice little circuit.

  3. Hi! First of all, I love your blog. I built my very first TS-808 clone (and first DIY pedal ever) thanks to you!

    I am preparing to build this tremolo pedal but I am really wondering about the wiring of the LED. I usually have only one free pin on my 3PDT. So when connecting the LED in bypass mode, one end will go to the 3PDT and the other will go to the +9V (through a 4k7 resistor).

    But in this case, the LED is also used for the rate and both its pins have levels that are different than +9V and GND. I usually use the grounded input 3PDT wiring. Would it hurt if I let the input floating during bypass? Because that way I would have the extra pin that I need for connecting the LED.

    Thanks in advance for your answer!

    1. I built one of these and I left the input floating and didn't have a problem. You should be fine.

    2. Hi,

      Thank you very much for your answer! I understood that the clicking of the 3PDT could be heard if the input is not grounded. Or is it just happening with distortion pedals?

      I have another question which might sound stupid to you: Does the LED have an actual function besides indicating the rate?

      In other words, if I do not use it, should I replace it with a wire or leave it open? In the latter case, I was thinking that it wouldn't hurt then to put the LED between the LED+ and GND and keep my classic grounded input wiring!

    3. That mostly happens with high gain pedals in my experience.

      The LED is only there to show the rate. If you don't want to use it just omit it.

    4. Thanks! I will experiment with the LED between LED+ and GND before soldering. Otherwise I'll leave the input floating!

      Thanks again!

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  5. i can use two leds? one in circuit for tremolo rate and another direct in dc for on/off?