UglyFace oscillation bleedthrough

[Noplasticrobots]

If I have my UglyFace set to oscillate and I bypass it, I can still faintly hear it through my amp and I can control it via the pot and everything. I've been having a hell of a time with the pot wiring on this thing, but it looks to be correct. Anyone else have this problem?

[petemoore]

  I believe it's just the high gain of the circuit or the 555 timer 'spiking' the power supply. I'm not certain what or if the fix is, but guess it'd be either not possible, having to do with supply filtering, more likely some shielding, perhaps even shielding and bypassing the Vsupply right up to the 555 itself...or, less likely..using the outside poles and throws of a 3pdt [to separate better] 
  Filtering
  Shielding
  Physically separating.
  But...IIRC...that circuit has the big spikes that are 'hard' to trim...YMMV, wait and see if other UF builder/tweeks come up.

[tungngruv]

Would wiring up two threshhold pots (one to be normal and the other for oscillating) and switching between them with a DPDT switch work? I ws going to try it on mine before I gave it to a friend. It seems the bleed through is only when its oscillating, and I think this is normal for the Ugly face.

[Noplasticrobots]

I was also thinking about just using a switch in the first place, but in the in-between setting of the pot you can sometimes get some cool effects. Turns out all these "problems" I've been having with my UF might just be it's normal operation!

[NoFi]

I would think it's normal too, well at least i had some bleedthrough if not using the treshold pot to cut it out.
The two pots idea seems like the way to go.

[Noplasticrobots]

How exactly would one hook up that DPDT switch for two pots?

[tungngruv]

I may be wrong but after looking at the schematic, coudn't you just use a SPDT switch, with the wire running to lug 2 of the Threshold pot attached to the center lug (or common of a stompswitch) of the switch. Then one side of the SPDT goes to lug 2 of one pot, the other side of the switch goes to lug 2 of the the other pot. Lugs 1 and 3 of both pots get attached to the same point in the circuit ( Lug 3 to +9 volt and Lug 1 to ground). Someone else care to help? I think this would really work and could be foot switchable.

[NoFi]

I was actually thinking of doing the exact contrary of you tungngruv. Connecting lugs 2 of the pots together and to the correct point on the circuit. And connecting lugs 1 and 3 of each pot to a DPDT switch. The purpose would be to avoid having the resistances of the two pots in parallel.
But your method is most probably correct. Maybe doubling the pot values would help.

[petemoore]

  Maybe use a 3pdt's extra pole and a throw to 'squelch' whatever in the circuit...find something that is 'safe' and will 'null' the oscillations, and use the bypass throw of the 'extra' row to have that connected when in bypass mode.
  Then if you get pops...post here...lol...just a blind suggestion.

[Tim Escobedo]

An extra pole in the footswitch could be used to disable the oscillator when bypassed. This'll do the job for sure.

Using a buffered bypass scheme may also work. Low impedance circuits are much less susceptible to picking up stray signals.

[Dan N]

I just wired the circuit so it powers on and off parallel with the LED. I've never noticed any lag when switching back on.

[tungngruv]

Hey NoFi, I noticed when I had my UF set to oscillate, when I turned the pedal off I could still hear a faint oscillation going on, even when the effect was switched off. I think that's what you are describing, right? If you hooked up another pot with the switch connected to both pots 2nd lug, I'm thinking that the switch would bypass one pot and use the second. I'm pretty sure they would react independantly of each other. That way, you could preset one to oscillate and the other to be "gated" and you could footswitch in between both sounds while eliminating the whining when bypassed. If I still had mine, it would be simple enough to unsolder lug 2, tack in a switch and extra pot to see if it would work. I may have to build myself another to try this........

[NoFi]

Hey NoFi, I noticed when I had my UF set to oscillate, when I turned the pedal off I could still hear a faint oscillation going on, even when the effect was switched off. I think that's what you are describing, right?

Absolutely.

If you hooked up another pot with the switch connected to both pots 2nd lug, I'm thinking that the switch would bypass one pot and use the second. I'm pretty sure they would react independantly of each other. That way, you could preset one to oscillate and the other to be "gated" and you could footswitch in between both sounds while eliminating the whining when bypassed. If I still had mine, it would be simple enough to unsolder lug 2, tack in a switch and extra pot to see if it would work. I may have to build myself another to try this........

Is that what you have in mind ?



It works but i think since the pots are in parallel, the resistance between lugs i and 3 is divided by two. It is possible to compensate and keep aprox. the same control range by doubling the pot values from 10k to 25k. Or by going the dpdt route and switch lugs 1 and 3 instead of lug 2. I think.

But Tim and Petermoore's solution would be ideally better to tackle the bleedthrough problem.
The two treshold pots is still a nice additional feature for when you don't want crazy oscillating between notes...
So now, what's the best way to disable the oscillator when in bypass ?  pin 4 to ground  ?

[tungngruv]

Yes, that's what I thought might work but you may be right. I thought that the switch lifting the #2 lug connection would remove it from the circuit but it may not be that easy. If you do figure tout, let me know. It's a great pedal.

[Processaurus]

Adding to what Pete and Tim said, you can stop the oscillation in bypass by holding pin 4 (reset) high.  I'd connect the common of the extra pole on the 3pdt to the +9v, and connect the effect side lug on that switches pole to the anode of the indicator LED (which goes through its resistor to ground), and the bypass side lug to pin 4 on the 7555 chip.  That'll do it.
EDIT: nevermind, it resets when pin 4 is held low, and oscillates when pin 4 is held high.  The uglyface works its magic by the audio input's frequency resetting the timer. 
So instead use the extra pole on the 3pdt to stop the oscillation in bypass by tying the common to ground, the effect side lug to the LED cathode, and the bypass side lug to the 555 pin 4 to hold the timer in its reset state. 

As far as a second footswitch to make it oscillate (which I love on mine), maybe a momentary stompswitch would be cool, for the UFO sounds

[NoFi]

That would maybe do it. Effect in = circuit board in.
My Ugly Face is partly dismantled so i can't try it right now.

[Processaurus]

You got it.   Sorry about the confusion.

[1878]

Hello Everyone.

I've just finished my first build !! I built the uglyface & I'd like to thank everyone here for the help they've given this poor first timer.

I built it with a DPDT footswitch first to make sure everything works. I want to add a 3PDT footswitch and LED like the diagram NoFi posted above. Will this solve the 'bleeding' problem when using the DPDT ?? Is this the same as 'true bypass' or am I getting confused again ??

Thanks in advance.