Making loop pedal for guitar ?

Discussion in 'The Projects Forum' started by gilley, Nov 23, 2014.

  1. gilley

    Thread Starter New Member

    Nov 23, 2014

    first of all apologies for grammatical errors , english is not my first language .

    I wanna make loop pedal for guitar. For all of those who don't know what that is , basicly, it is just a pedal that records signal from guitar and then "replays" it over and over again, while I ( or anybody else ) play over that.

    So it goes : guitar ---> loop pedal ----> guitar amp

    Basicly for this pedal I would be happy if I could just make it work, 20 seconds of recording would be more than enough, and I don't expect extraordinary sound quality.

    So I have 2 major question for now, since I have never done something like this and is beyond my level.

    1. First I need A/D converter to convert analog guitar signal into digital right ? Which one should I use, and why ?

    2. What can I use as a "heart" of pedal. This signal that A/D converter will convert needs to be saved somewhere and then played again. What IC or microcontroller can do that ?

    Hope I am not asking too much.

    Thanks in advance,

  2. alfacliff

    Well-Known Member

    Dec 13, 2013
    these have been built before with a so called "bucket brigade" chip, a voice record / playback chip like the ISD1000a. it does all the functions you want. radio shack used to sell these as p/n 276-1325 with a sheet showing the wiring of the chip.
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
    There are echo chips pt2399. The problem with most of these chips is a bit of hiss/noise (all the time) and digitized sound at low volumes. Les Paul used a magnetic tape with a big loop as a delay - at least that is one theory. A digital solution was not likely in the early days that he did it. There are plenty of youtube videos of him demonstrating it - without showing the actual device.

    If you want a full digital solution, I would start with a "raspberry pi" for $35. Add a USB microphone and off you go. There is likely software already out there somewhere. There are even guitar 1/4" jacks to USB.
    Last edited: Nov 23, 2014
  4. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
    I don't think that this is a project for someone with zero experience of electronics. To design a loop pedal you will need a good understanding of both digital and analogue electronics and possibly micro-controllers (depending on the level of control required). To get an idea of what is involved; take a look a some of the on-line schematics and try to understand how other people have done it.

    What electronic devices have you designed or built previously?
    Last edited: Nov 24, 2014
  5. gilley

    Thread Starter New Member

    Nov 23, 2014
    I am currently 3rd year of tehnical college in Croatia, so we can say I have some theoretical background, but I have no practical knowledge (atleast not anything worth mentioning ).

    We have done some programming in assembly so I know what it looks like, and I have done few projects on arduino boards.

    I have been speaking today with one of my professors and I mentioned him what I wanna build, and he also suggested me raspberry pi as cheapest solution so I will go with that. Yes I would like full digital solution, mostly becouse of learning process :)

    Thank you