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Passive diod OD Help Please

Discussion in 'Pickups & Electronics [BG]' started by cnltb, Mar 14, 2013.

  1. cnltb


    May 28, 2005
    Hi, I found an "instructable" for a passive overdrive circuit online.
    It has a potentiometer in the middle of it and I am now wondering if one would be able to wire it in such a way that omits the pot.
    Basically just on and off with no pot.
    Here is a link to what I am talking about.
    Help on this would be greatly appreciated!
    Thanks in advance!
  2. Hi.

    It's possible, but do experiment with the potentiometer and possibly install a teminal for easy resistor swap.

    Semantics I know, but the device is far from overdrive though, just a diode distortion.

  3. ctmullins

    ctmullins fueled by beer and coconut Gold Supporting Member

    Apr 18, 2008
    MS Gulf Coast
    I'm highly opinionated and extremely self-assured
    More like a fuzz, really. I did it once. Wired it to a switch. Played it like that for a week or so. Then I put away childish things...
  4. cnltb


    May 28, 2005
    I might do that, thanks!
    How would you wire this though just minus the pot?
    I find a simple on/off thing very tempting for a very first experiment.
  5. abemo


    Feb 27, 2012
    Arvada, co
    You would just wire one side of the switch to the signal wire, and the other side to the diode (or diodes) going to ground.
  6. abemo


    Feb 27, 2012
    Arvada, co
    Reading through it all, basically just bypass the switch. Wire in the bypass, and the signal wire that was going to the pot just goes directly to the diodes.
  7. Like someone already said, this is nowhere NEAR an "overdrive" circuit. In fact you're going to find that it actually lowers your signal output level. Overdrive circuits are used to OVERdrive a circuit or amp by producing a LOT of properly voiced gain, like 20db (at least) or more.

    This is a novelty at best. By the time you buy an enclosure ($10) the 3PDT footswitch ($5), the pot and knob ($3 minumum) and the diodes (??) for the results it produces you may as well buy a clean booster circuit ($10 kit?) and create a REAL overdrive (a gain boosting circuit that is used to drive something after it into distortion). Add a couple of diodes after the boosted signal to create some clipping and you'll have a truly crappy distortion unit!

    This may be something "fun" to tinker with, but I highly doubt you'll like the results. Diode clipping (when done incorrectly) sucks the low end from a circuit.

    In any case, have fun with this. One question, without an LED to tell you when the circuit is engaged how will you know if it's engaged or not if you want to use it?

    For super simplicity, you may simply add the diodes inside of your bass, just solder them from the "hot" to the "ground" and you're done. Stick a toggle switch in there to disconnect the diodes from the ground to turn them "off". And remember that they must face opposite directions for them to work.

    Don't expect much though. Diodes clip a lot better when they have a boatload of signal going through them, and remember that all of that signal that is going through those diodes to ground is taken from your output .. so your output level will be reduced.

    This thing is like bicycle without wheels. Technically it's a bike, but all you can do is drag it around and claim you own a bike.
  8. cnltb


    May 28, 2005
    Thanks, all for your help!
    Fun and an experiment is all I am expecting.
    We'll see...

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