My new circuit - "1983 Fuzz" Old School Atari type fuzz

[kodiakklub]

by all means ive been waiting for a bigger fish to swim into this pond, no offense to anyone's valiant efforts. i will update my schem tomorrow night and post it. i will also try and get this breadboarded by the end of the weekend.

[Earthscum]

Sorry, man... not having any luck, either. It works for a couple notes, then it starts to "decay" and then I can hear it latch and no more sound. Starts to get a tiny warm, but I shut it down immediately after every time it latched.

UPDATE: Of course, I dont give up, I just wait for something to come to me... take the 100k and drop it straight off of pin 9 to ground. Now is the strange part... it depends completely on where I plug what into. It doesn't play well, and I honestly thing you may have found a good combination of things that are on the very edge of what the 556 wants to do. Still playing around with it. I'm trying isolating the supply from chip to chip and some other ideas.

[timd]

Well - it seems like you got it to work a little bit...did you use the 100 R resistor? Also, did you rotate the pots? On my final build, I can play all day with it never overheating, but when I mess with the knobs and have both pots in an exact position it will kill.

[timd]

Also, as trivial as it sounds, could the issue stem from the specific manufacturer combo of 386 and 556 chips?

[Earthscum]

Also, as trivial as it sounds, could the issue stem from the specific manufacturer combo of 386 and 556 chips?

Not too sure. I'm using TI NE556N. The 386 section seems to be working just fine... it's in one of the connections or manufacture of the chip, possibly. I didn't get any change out of using a 100R.

The 500k didn't do anything for me, and the 100k, I found, did a little bit. If you turn it to least resistance, it will cut out and stuff. You may consider a limiting resistor in there (so you don't kick the knob while it's off and find when you kick it on that you toasted it).

One thing I'd recommend is procuring a couple more chips (one of each, not batch, lol). Try building a second one on the breadboard and see if you can repeat it. Then compare to my updated schem, as well as your hand drawn one, and see if it all matches up right. This may be one of those "voodoo" circuits, lol... like my Scrynth. I can whip one up in a few minutes on the board and it works great every time, but the couple others that have tried it have had issues. It's one that I've been working on a second version of, a 'super' version of, and another circuit based on it. The 'based on' version isn't going so well because it loses the cool gating, but I'll eventually get something figured out. Sometimes it just takes a bit of time for a good idea to evolve into a realistic working item. 

[artifus]

tim are you running this from a battery or psu? if battery, have you measured its voltage?

also:

uglyface

crashsync

555modifier

http://www.beavisaudio.com/library/555/555.htm

http://www.kpsec.freeuk.com/555timer.htm

i've slammed a 555 frequency divider with a 386 for lofi 8 bit sounding fuzzy fun too.

*edit* i sometimes wish that there were more convention in specialist ic schematics, timers, decoders, cmos, etc., it would make the compare and contrast so much simpler.

[timd]

I'm running this from a power supply. I have those voltages on a previous page. I too like slamming stuff with the 386!

[timd]

Anyone get this thing to work yet?

[timd]

*Update - I just spent a bunch of time on the breadboard with this again and have the following:

You don't need the 500K pot off pin 1 of the 556 chip. Its contribution was very minor, and the surviving 100k pot can color quite a bit. You can even dial in sweet spot oscillations.

So, its now a 2 knob (1 if no volume) pedal!

[~arph]

You don't need the 500K pot off pin 1 of the 556 chip. Its contribution was very minor, and the surviving 100k pot can color quite a bit. You can even dial in sweet spot oscillations.

Yes that makes sense.. that part of the IC is not used at all.. I think you can swap the 556 for a 555 altogether.. makes for a smaller footprint.

[timd]

I'll breadboard with a 555.

[kodiakklub]

tim: you BB'ed it a second time and got it to work? im still watching to see if this thing is gonna work on a second or third pass at it. still very interested.

Oh! and what about changing the volume pot to be more of a wet/dry mix kind of pot?

[artifus]

Oh! and what about changing the volume pot to be more of a wet/dry mix kind of pot?

be sure to put an appropriate resistor in series with the 555/556 output to drop the level as it will be close to 9v  and overwhelm the dry signal in the mix pot.

*edit* also, if you still have a 556 (or two 555's) laying around why not try doubling it up? output of one 555 to the other. or stereo?! if you're gonna fluff stuff up, fluff it up good.

[kodiakklub]

how about this to mix?

[artifus]

wouldn't c4 be better placed between pin 2 of vol pot and out for dc blocking?

[kodiakklub]

most likely i was just ripping off of the ampeg scrambler schem as that was the first pedal off the top of my head that had a wet/dry mix.

[timd]

*edit* also, if you still have a 556 (or two 555's) laying around why not try doubling it up? output of one 555 to the other. or stereo?! if you're gonna fluff stuff up, fluff it up good.
[/quote]
So what you mean is to run the circuit output back into pin 3 (the other control pin) and then to output? What do you think this would do for the sound? I'm not at my workbench, so I can only guess...

[timd]

And yes kodiakklub - its working fine on another breadboard build. If I were you, I'd breadboard it with the "one knob" version. Look at the schematic and the the photos. 

[timd]

I figured it was time for me to stop procrastinating about this circuit and give it another go. I recently was revamping my pedalboard and put the final boxed 386 fuzz (see youtube video link in this thread) after 2 distortion pedals and it cut out after a few seconds each time, but is fine by itself. Many people have had the 556 chip heat up dangerously right after applying power. Does anyone have a suggestion to stop the heat up of the 556 but still retain the proper fuzz sound?

Also, is there any mind greater than my own that can spot the reason that the 556 is being taxed like that from the schematic? The chip can take voltages higher than 9v easily.

Thanks in advance. I want to get this right for myself and everyone else that has had issues with this circuit.

[timd]

Alright - I came up with this - a simplified version with a 555 chip and one pot. I tested it on a breadboard and it works fine - no heating up of the 555. Let me know what you think.