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DIYstompboxes.com  |  DIY Stompboxes  |  Building your own stompbox  |  XOR Ultra Sick-Did This Ever Happen To You? 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: XOR Ultra Sick-Did This Ever Happen To You?  (Read 485 times)
Arn C.
Posts: 1289



XOR Ultra Sick-Did This Ever Happen To You?
« on: January 24, 2006, 08:50:02 AM »

I put this circuit together quite a while ago and could never get it to work right.  So, after it sat around doing nothing for the longest time, I figured I tear it apart and use the box for another project.

After I cut all the wires from the circuit board and desoldered the scraps from the pots, I looked at the board and noticed the chip was not pushed all the way in due to a cap(little box one).  It was hitting the cap which wouldn't let it get seated correctly. So, because of this only like half of the chip was making proper contact.  I believe this is why I only got the occasional "Blat, Blat, Blat"

Damn, now I am going to put all the wires back and try it again.

Did anyone ever get some sound files for this pedal?

Peace!
Arn C.
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John Lyons
Posts: 5754


Basic Audio


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Re: XOR Ultra Sick-Did This Ever Happen To You?
« Reply #1 on: April 01, 2006, 11:44:44 PM »

Arn C.

Missed this post the first time...

I have been wrestling with this circuit for a while. I had it working with the exception of a pretty hard gating, Then Peter snowberg made a suggestion to bias the pin one input. I made a voltage divider between +9v and ground with a trimmer pot and it came to life without the gating. his was all on a breadboard proto layout. Made a PCB layout and now it gates again!!!! Argh!!!!!. I can "bias" the input but it either hard gates or when I find the sweet spot it gates verry little but then "motorboats".... Put, Put, Put, etc.

So basically It has 5vdc (+/_) on the input pin 1.

I'll look over the PCB and layout again but anyone have any suggestions to the "biasing" of the input to the 4070 chip?  Kind of an odd chip to use in a fuzz but it gan get some nice/crazy buzzsaw sounds.

Here are some notes/ schematic and sound samples on my site:    http://www.mrdwab.com/john/XORUS.html

John

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Basic Audio Pedals
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John Lyons
Posts: 5754


Basic Audio


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Re: XOR Ultra Sick-Did This Ever Happen To You?
« Reply #2 on: April 01, 2006, 11:58:49 PM »

Meant to say that Paul Perry helpd with the bias info...sorry bout that Paul...
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MartyMart
Posts: 6064


Martin L / Berlin for a while


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Re: XOR Ultra Sick-Did This Ever Happen To You?
« Reply #3 on: April 02, 2006, 03:20:24 AM »

That almost happened to me with my Maestro Fuzz, as I was about to "rip it up" I
noticed a resistor "through the board" but hardly soldered at all ... flowed some new
solder and "BINGO" - working circuit !!

MM
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"Success is the ability to go from one failure to another with no loss of enthusiasm"
My Website www.martinlister.com
John Lyons
Posts: 5754


Basic Audio


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Re: XOR Ultra Sick-Did This Ever Happen To You?
« Reply #4 on: April 02, 2006, 05:30:01 PM »

I played around with the thing a bit more and confirmed that if it's "biased" at about 5 volts at the pin 1 input the gating stops.
I don't understand why this is so. I seems odd to me to have 5 volts DC at the input. Wouldn't I need a cap there to block DC? But then there would be no bias current.... Can anyone explain this?

Also, the range of ungated opperation with a 1 meg pot is supper narrow. Just barely up or dwon in the rotation and the gate closes... I had to put in a full size 24mm pot just to find the sweet spot, a 1 meg trimmer was too sensistive to adust to get the sound to come on...

John



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