This pedal is killing me, any help would be great

[McGhie]

My 'stock' caps are 0.01uF on the input - and think i'll try a 0.1uF on the output - as there's a bit more bass coming out (hopefully).

I'll try the same thing then, thanks!

I'm due some 'solder-time' tonight

Wicked,  let me know how it turns out!!!

[McGhie]

That's it! I give up! I've tried everything, I've switched the wires and added DC blocking caps on the input and output, and it sounds EXACTLY the same! This is not giving me very high morals for such an easy build. I just can't get it to work, I'll try putting a headphone amp in it instead, and if that doesn't work, I'll kill someone.

[McGhie]

bump for great misery

[Ed G.]

If you're getting a loud hum, there's likely a ground issue somewhere.
I'd take a multimeter and make sure that everything is grounded as it should be. Plug in a guitar cable, even a short one, and test that the barrel (not the tip) is grounded, on both the input and output jacks.

[Cardboard Tube Samurai]

Any chance you could post a couple of photos of your circuit? A few extra sets of eyes might be able to spot something that doesn't seem evident to you. I'm hoping to have a crack at this one on my breadboard a bit later in the hope that I can shed some light on it for you because I know how frustrated you are right now and it's not fun (I've been there too!)

[McGhie]

If you're getting a loud hum, there's likely a ground issue somewhere.
I'd take a multimeter and make sure that everything is grounded as it should be. Plug in a guitar cable, even a short one, and test that the barrel (not the tip) is grounded, on both the input and output jacks.

I'll make sure to check my grounding, thanks!

Any chance you could post a couple of photos of your circuit? A few extra sets of eyes might be able to spot something that doesn't seem evident to you. I'm hoping to have a crack at this one on my breadboard a bit later in the hope that I can shed some light on it for you because I know how frustrated you are right now and it's not fun (I've been there too!)

I quite agree really, I'll find my camera this evening or tomorrow (am busy) and upload some shots.
And thanks for being understanding!

[Cardboard Tube Samurai]

No probs. I'm actually really sick at the moment and I'm going away for the weekend. I also don't have a spare LM386 lying around like I thought I did so there's not much chance of it happening for a few days now. I went to do it yesterday but made the discovery. I'd usually just pick one up from work as I need it but I've been too sick to go in. I'll keep you posted

[McGhie]

No probs. I'm actually really sick at the moment and I'm going away for the weekend. I also don't have a spare LM386 lying around like I thought I did so there's not much chance of it happening for a few days now. I went to do it yesterday but made the discovery. I'd usually just pick one up from work as I need it but I've been too sick to go in. I'll keep you posted

Wicked, because mine just.. refuses to work.
Although, I found a problem in my box. The DPDT simply did not work ( broken 0.o ). I have switched to a 3PDT switch and added an LED, and It still makes the same sound though.. You can see it all in the picture's I'll be taking tomorrow if I have the time. High school just started yesterday here, so I'm rather busy...
I'll keep you posted too

[newfish]

Bare bones version on my breadboard - with in and out caps...

No LEDs, no DPDT switching, just straight in and out connections.

Same result I'm afraid.  All oscillation, and no amplification...

I'm still using the original (not posted in this thread) layout - so that's my next trial.

If I get chance this week, I'll rebuild (3rd time lucky...) and see what happens.

[runmikeyrun]

something's F'd up with the circuit then or something.  I've had pedals like this, it's hard to admit defeat but sometimes you just have to cut your losses.  I gave up on an uglyface, ended up buying one from a forum member.  That was much easier!!!!

[Ed G.]

Is there a schematic for this, or just a layout? You might try to compare this to a similar circuit that I know that works, like Aron's "Smash Drive"

[DougH]

The shorting or pins 1 and 8 looks suspect to me. According to the datasheet, they need to be capacitively coupled (although the square wave oscillator circuit does show them shorted, hmm...). IOW, stick a cap across them for max gain of 200, leave them open for gain of 20, stick a cap and resistor across them for something in between.

Also, the pin 7 bypass cap is usually shown connected to ground in example schems in the datasheet.

Check the datasheet here: http://www.national.com/mpf/LM/LM386.html

[Gus]

A schematic would help.
is this it?
http://www.aronnelson.com/gallery/main.php/v/zond/GEARBOX/UNDERFUZZ_001.GIF.html

IIRC years ago when people posted about people cloning smoky? amps they found 386s of different brands made a big difference.  IIRC the one they liked was the JRC386 and the gain pins were shorted together not cap coupled.

What brand and complete part number 386 is use in this threads build?

[McGhie]

runmikeyrun - this is what I'm thinking.. maybe it isn't worth it..

newfish - aww, @#$%... a note I must add is that mine does the same thing/sound when bypassed and when active...

DougH - are you saying that a small value cap between pin 1 and 8 could suddenly make it work?

Gus - That's the schem alright.. But if the difference in brand mattered with the same IC in another circuit, I reckon it'll be the same thing here, right? the packet of mine says"LM386N-1/NOPB", but I don't see a brand anywhere..

[DougH]

Small or big capacitor - whatever. The best thing you can do is experiment. That's why you should always breadboard a project before soldering it up - 1) Make sure it works and 2) Make sure you like the way it sounds.

[McGhie]

Small or big capacitor - whatever. The best thing you can do is experiment. That's why you should always breadboard a project before soldering it up - 1) Make sure it works and 2) Make sure you like the way it sounds.

Right, but do you reckon it'll make it WORK?

[tiges_ tendres]

As I understand it there are a number of applications with short the pins for the increase of gain.  The ugly face is one such pedal, Doug Deeper's Freak Out fuzz is another.  Also I think that Crank pedal with the lpb boost in front also has the gain pins shorted, or at least has a pot between the pins.


http://www.aronnelson.com/gallery/main.php/v/BarcodeVeroLayouts/Vero/FOF.jpg.html

IC is too small on the layout, but Ive had good success getting this one to work.  I think it might be missing a track cut at C1 though

[Barcode80]

As I understand it there are a number of applications with short the pins for the increase of gain.  The ugly face is one such pedal, Doug Deeper's Freak Out fuzz is another.  Also I think that Crank pedal with the lpb boost in front also has the gain pins shorted, or at least has a pot between the pins.


http://www.aronnelson.com/gallery/main.php/v/BarcodeVeroLayouts/Vero/FOF.jpg.html

IC is too small on the layout, but Ive had good success getting this one to work.  I think it might be missing a track cut at C1 though

nope, no track cut needed, as the verified comments below the image speak to

you are right about the IC though, never got around to fixing it...

[McGhie]

Until anything new turns up, or anything from Cardboard Tube Samurai, I'm going back to building my Atari Punk Console... The Underfuzz just refuses to work...

[DougH]

Small or big capacitor - whatever. The best thing you can do is experiment. That's why you should always breadboard a project before soldering it up - 1) Make sure it works and 2) Make sure you like the way it sounds.

Right, but do you reckon it'll make it WORK?

Don't know. According to the schematic of the LM386 on the datasheet, I don't see why shorting the pins would be a problem, as they appear to be at the same DC level.

Again, throw this sucker on the breadboard and play with it. Sometimes you have to roll up your sleeves and get down in the dirt with the dogs.

The guy that posted the schem has less than 10 posts IIRC and appears to be long gone. No sound clips, hmmm... Wonder if it ever really worked? Maybe he'll see this thread at some point and come out of hiding to defend his honor... Heh-heh!