Do more with your Uglyface :-) ......?

[frequencycentral]

I'm onto a feature creep version of the Uglyface and looking for more knobbiness.

Uglyface: http://www.experimentalistsanonymous.com/diy/Schematics/Fuzz%20and%20Fuzzy%20Noisemakers/Uglyface.gif

Couple of ideas. Firstly, it occured to me that the octave up section of the Slacktave II might make an interesting addition, being driven by the Ugly's 7555. I *think* the 7555 would be perfect to drive the oct up section - what do you think world? Might be interesting to have it on a blend pot.

Slacktave II: http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=39358&g2_

Second. I'm sure an inverted envelope mod could be done somehow. Stock, the LED lights up when you hit a note, then fades out. The LED for an inverted envelope would have to be on when no note is present, cut out when you hit a note, then fade in. I'm sure the answer is staring me in the face............maybe a second LED back to back with the first? And some switching to select which LED is used? Or maybe just use the stock LED with a DPDT to invert the LED itself?

[theundeadelvis]

Rick - I wish I had some technical knowledge to share, but I don't. I will say however, your proposal sounds awesome. I love the Uglyface, and would love to be able to get even more beautifully chaotic noise out of it.

[earthtonesaudio]

The 7555 ought to drive a CMOS XOR easily... but do make sure to use the pin 3 (square wave, logic levels) output.

There are a couple ways you could do the inverted envelope.  One way would be to put a (NPN or N-channel MOSFET) transistor after the Sensitivity pot.  Gate/Base to lug 2 (with a 10k resistor in between), Source/Emitter to ground, Collector/Drain to V+ through a resistor.  Then the LED would go from Collector/Drain to GND.  This would mean the transistor is off when no signal is present, so the resistor current goes through the LED; and when signal is present the transistor turns on and shunts current away from the LED. 
Another way would be to use a depletion mode device like a JFET, but biasing would get more complicated.

[egasimus]

Maybe an external LFO input or two? That's something I intend to add to my Uglyface, but I need someone to tell me how .

[earthtonesaudio]

Maybe an external LFO input or two? That's something I intend to add to my Uglyface, but I need someone to tell me how .

Pin 5

[egasimus]

Pin 5? I was thinking something along the lines of the built-in LFO mod - connecting the external LFO through a resistor to one side of the Sensitivity pot...

[slacker]

Yeah that will work fine.

[frequencycentral]

One way would be to put a (NPN or N-channel MOSFET) transistor after the Sensitivity pot.  Gate/Base to lug 2 (with a 10k resistor in between), Source/Emitter to ground, Collector/Drain to V+ through a resistor.  Then the LED would go from Collector/Drain to GND.

Thanks Alex. Like this?

Yeah that will work fine.

Thanks for the confirmation Ian.

[earthtonesaudio]

Thanks Alex. Like this?

Yep!

[nocentelli]

... back from the dead.

Rick, i'm assuming you had no joy with the arrangement you've drawn out above? I've been tweaking the Uglyface on the breadboard for a while now, and would love to try a reverse sweep, but can't get the schem above to work with either a 2N2222 or BS170.

Lower the input (base/gate) resistor? Trimmer for the collector resistor? The LED does not light when connected to the collector no matter what the sensitivty pot is set to, or how much guitar signal is present. I have increased the 386 output -> sensitivity lug 3 cap (22uF instead of 2u2) as per Mick Bailey but can't see how this would make a difference.

Apologies for the necro post.

[frequencycentral]

I had the same experience with that mod, never got it to work as is. Didn't really take it any further, but there must be a way to do inverted envelopes.

[nocentelli]

Thanks for the reply, Rick. I'll keep working on it. I'd also be interested in a way to adjust the decay of frequency sweepm I feel part of the problem is the very simple/clever way this seems to be accomplished - I don't really understand how the frequency pot works, but I assume the envelope detection/sensivity part is just the LED being driven directly by the audio output of the 386 amp? I've also had some interesting results with increasing the coupling cap from 2u2 up to 100u - whilst it becomes easier to trigger the sweep (and the sens pot seems to become more useful), a lag appears between the playing of a note and the LED illuminating (cap charging), so 22u seems a good compromise. I also tried different colour LEDs, but at this point I started to enter uglyface psychosis and could well have imagined any perceived differences...   

[frequencycentral]

I wonder if a LED from +ve to lug 2 of the sensitivity pot would flash inversely to the first LED?

[nocentelli]

By jingo - You might have it. Did you know that blue LEDs glow a beautiful magenta milliseconds before they die? I'll just get a resistor in there   and get back to you.

<edit - nope: Unresponsive so far, but i'll tinker with this for a while>

[earthtonesaudio]

I wonder if a LED from +ve to lug 2 of the sensitivity pot would flash inversely to the first LED?

Yes this would work. But careful: if you turn the sens pot all the way to ground your LED will explode.  Put an extra limiting resistor somewhere in there so that can't happen.