Beavis PWM help

[squeezyphresh]

Hi I'm building my very first pedal and I've seem to have gotten stuck. I have the circuit exactly as shown in the schematic I'm using (http://beavisaudio.com/bboard/projects/bbp_PWM.pdf), but I don't get anything but basic feedback from the amp (essentially strumming my guitar doesn't seem to do anything while the effect is on). I'm pretty sure I've got my push button set up correctly since I can play clean sound. Something important to note is that my LM386 is very hot (too hot to touch for more than a second) but I've read that was a common problem. Is it possible that I've grounded something wrong or that something in the schematic is misleading? Any help would be much appreciated. I've been up all night with no luck.

[blackieNYC]

Take a fresh look at it here: http://www.jiggawoo.eclipse.co.uk/guitarhq/Circuitsnippets/snippets.html
The Beavis is right though.  Have another 386?  I dont remember it getting very hot.  Sounds like a short. Is your 500k pot set about halfway?  Can you hear it if you take your output straight (careful!) from the 386?  That thing is powerful.  Attenuate. Don't blow up your amp. I may have a dud 40106.
Weird effect. Cuts notes off abruptly. Love it.

[dwmorrin]

Something is wrong with the 386 if it is hot.  I've built that fuzz without problem. One of my favorites.
Get rid of whatever button you're talking about.  Just build it without a bypass first.  Simplify.  As blackie suggests, check the 386 direct output.  I would suggest building a straight 386 circuit from beavis' site to check your chip and setup, and then throw the 40106 into the equation after.
Maybe you're sending the 386 output into the wrong pin of the 40106.
Post a pic of it if you can.

[squeezyphresh]

i actually just fixed the heat issue. it was apparently just a grounding issue. I also removed the push button. I don't get any sound at all though now...

update: now the 40106 is getting really hot... I think both pots were backwards but that didn't fix the heat issue from the 40106. If i touch the guitar strings I get a popping noise, but thats about it. Both pots seem to affect the output, just for some reason my guitar won't go through

[squeezyphresh]

That's my breadboard right now. What would cause a schmitt trigger to get hot?

[dwmorrin]

Photo is a bit blurry.
My thoughts are:
-Why is battery and power jack being used? Pick one or the other. Also, where is battery negative going??
-The ground rails don't look like they are connected together. Are they?
- What power adapter is that?
- Voltages??

[Tony Forestiere]

Is the jack on the right the Input? Switching jack and not TRS (Tip-Ring-Sleeve).

[squeezyphresh]

Photo is a bit blurry.
My thoughts are:
-Why is battery and power jack being used? Pick one or the other. Also, where is battery negative going??
-The ground rails don't look like they are connected together. Are they?
- What power adapter is that?
- Voltages??

I was going to have it so that the jack controlled whether or not it used up the battery but i'm thinking of removing the batter and switching to just the dc jack. If I was going to take the battery out, what do I do with the 3rd pin (first goes to low, second goes to high, but third goes to what?)

The ground rails aren't connected... i guess they should be

here is the power jack: http://www.cui.com/product/resource/pj-202a.pdf

By voltages are you asking what the power supply outputs? it's 9V. Edit: i'm dumb. I assume you mean voltages measured by the DMM. I don't have a DMM on me right now since I'm at home rather than at college... Luckily I'll be going back in a couple of days.

Is the jack on the right the Input? Switching jack and not TRS (Tip-Ring-Sleeve).

Switching jack? do you mean the switch that controls whether the effect is on or not? I'm not adding that until later. Right now the circuit always send the guitar through the effect.



Update: putting all the grounds on the same rail just seems to overheat the chips... and doesn't fix any of my problems. I have no clue why. Does the dc jack ground need to be seperate from the other grounds?

[deadastronaut]

check for continuity across those + and - rails too on the breadboard

sometimes the breadboards are split in the middle..and need little jumpers.

[squeezyphresh]

Ok i've checked for continuity across the rails and all is good. about 9.33 V are being put through the circuit. All the grounds are connected at the same node. chips are still heating up and are too hot to touch if you leave your finger on there for about 10 seconds. still no output from the guitar. Any ideas guys?

[pinkjimiphoton]

if ya did reverse the chips, you probably roasted them both. they don't take too much abuse before they crap out.
generally, overheating is a short circuit in my experience. do you have more chips? i would try them first.

that said... i built a few of these with no problem, but i don't think they sound all that great.

if ya want something REALLY cool, build an uglyface.

make sure it has the lfo!

[squeezyphresh]

if ya did reverse the chips, you probably roasted them both. they don't take too much abuse before they crap out.
generally, overheating is a short circuit in my experience. do you have more chips? i would try them first.

that said... i built a few of these with no problem, but i don't think they sound all that great.

if ya want something REALLY cool, build an uglyface.

make sure it has the lfo!

I definitely didn't reverse the chips. I made the effort to look at the datasheets to check about 3 times haha. I can order more chips but I'd rather not have too... I don't see how I could have a short circuit because I followed the schematic and double checked it an everything, unless you are telling me the breadboard in the picture has a short circuit, I shouldn't have one.

[dwmorrin]

...unless you are telling me the breadboard in the picture has a short circuit, I shouldn't have one.

Well, does it?  Put your meter on it.  Breadboards are breakable.