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Thursday, 10 October 2013

DOD 555 Performer Distortion

The orginal unit uses two 9V batteries and electronic swithing. I removed the latter, but left the supply voltage wanting the 18V. With this, i also left the (possibly) destructive polarity protection method in tact. For the supply, one can use two batteries or add a small daughter board to pump the standard 9V voltage close to desired 18V. That pump would be something like this or this.




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6 comments:

  1. Travis10 October 2013 at 20:52

    Yay nice to see some fresh posts!

    Great looking layouts, mirosol

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  2. Unknown20 November 2013 at 20:54

    Mirosol, in order to offset my take, take, take, attitude, I attempted to verify this one - the first part is ok ie getting 18v into the board from the 555 pump. Also my voltages look ok across the IC pins 1,2,3 are 8.1,8.1 and 7.9 respectively, 18v at pin8 and 8.1 at 7,6 and 5. Ive substituted a tl072 and used a 500k log instead of a reverse.
    Also I dont know if you can explain this - when I plug the guitar into the input and probe across the input jack I get nothing. Sorry - one last thing - gain 2 should it be linked to gain 1 or is gain 1 to ground ?

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    Replies
    1. mirosol21 November 2013 at 06:31

      Gain 1 is not connected. If you did connect that to ground, it could explain it as well..

      Could you be having some of the voltage leaking to the input of the circuit? Or possibly a ground issue?

      I've ran into similar "dead input" issues sometimes myself, and it's usually something really stupid i've missed. Your voltages look ok, so this could be something simple too.
      Does the 1M reisistor measure 1M? I mean, if you have accidentally something like 1K in there, then the signal would be dead.
      +m

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    2. mirosol21 November 2013 at 06:51

      Oh. I think you won't like the log pot for gain. That should just be quiet and you'll get all the action at the very last 3% of the sweep. You could try 1M lin pot for the gain and place extra 1M reisistor between lugs 2 & 3. That would get you pretty close to 500K rev log.
      +m

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    3. Unknown21 November 2013 at 15:54

      Hi Mirosol, turns out it was a bad jack socket, shorting at the input, so this ones done. All I can say is oooof, lots of easy sustain at the top end. I only had a 1M log so the sweep is not perfect but Ill get a proper pot and box it up. Woohoo first one Ive verified yeah !!

      Delete
    4. mirosol21 November 2013 at 16:10

      Cheers Jim! I'll tag it right away.
      +m

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