Parallel Universe Questions

[tiges_ tendres]

I just finished a parallel universe using dragonflys layout and I had a couple of questions.

Firstly, the oscillate mode works fine at some settings, but sometimes just stops.  For example, I can turn the frequency knob, after about half way, the self oscillation drops out, then will swing back in.  It seems to vary depending on where the gate and gain knobs are set to.  I found a fix for this by running a wire from Pin 3 of the frequency pot to pin 2 of the frequency pot.  This pretty much gives me on demand self oscillation which I have made switchable.

Also another thing I've noticed is that when in self oscillation mode, at certain settings, the guitar signal doesn't make it through at all.  Is that normal?

Otherwise, this has been a fun build!  Great fuzz sound.

one another question, what makes this thing oscillate?  I'm presuming its altering the voltage that the 386 sees at certain points, but I dont know all that much about this stuff.

[tiges_ tendres]

ok, so I think its more to do with the gain pot. 

On my P.U, when the gain is set less than 90%, I get problem with the oscillation droping out.

Love this thing!

[cjb]

Hi - first post, though I've been lurking for a little while.  I just built the Parallel Universe, and I'm having the same oscillator issue described above.  When the OSC pot is in the bottom or top end of its travel, I get oscillation - in the middle of its travel, the sound drops out.  I used the first (more simple) schematic from EA:

http://experimentalistsanonymous.com/diy/Schematics/Fuzz%20and%20Fuzzy%20Noisemakers/Parallel%20Universe%20Schematic%20(old).gif

I'm wondering if I need to play around with the caps in the oscillator section - try some different values?

One difference is that I didn't have an LM386 handy, so I used the NTE equivalent - I think it's NTE823.  Are there any functional differences I should be aware of?

[tiges_ tendres]

Hi - first post, though I've been lurking for a little while.  I just built the Parallel Universe, and I'm having the same oscillator issue described above.  When the OSC pot is in the bottom or top end of its travel, I get oscillation - in the middle of its travel, the sound drops out.  I used the first (more simple) schematic from EA:

http://experimentalistsanonymous.com/diy/Schematics/Fuzz%20and%20Fuzzy%20Noisemakers/Parallel%20Universe%20Schematic%20(old).gif

I'm wondering if I need to play around with the caps in the oscillator section - try some different values?

One difference is that I didn't have an LM386 handy, so I used the NTE equivalent - I think it's NTE823.  Are there any functional differences I should be aware of?

I just learned to love it as it is.  Although the tip in the first post does help. 

[cjb]

I'll definitely try the jumper on the Freq pot...are you jumping from the wiper to the 0.1uF or 10uF cap?  Does the OSC switch still turn it on and off as expected? 

[cjb]

Okay, played around with it a bit over my lunch break...the jumper on the freq pot didn't seem to help the issue.  I did find that the oscillator swept through a full range if the starve switch is flipped, though (enabling the 2.2k resistor) - the starve and gain pots seem to affect the frequency of the oscillator as well.  Lots of weirdness going on in this circuit, but I like it; I think I'll go ahead and put it in an enclosure, which will make it easier to play around with...

[tiges_ tendres]

Okay, played around with it a bit over my lunch break...the jumper on the freq pot didn't seem to help the issue.  I did find that the oscillator swept through a full range if the starve switch is flipped, though (enabling the 2.2k resistor) - the starve and gain pots seem to affect the frequency of the oscillator as well.  Lots of weirdness going on in this circuit, but I like it; I think I'll go ahead and put it in an enclosure, which will make it easier to play around with...

Yeah, you can't have the gate on, it takes too much juice away from the oscillator.