Super-simple Distortion/fuzz Schematic

[Ben]

I'm bored and I'm wondering if I can make something from the scrap parts I have lying around.

Theyre all from an old effects pedal I canibalised and theres a few parts I could salvage from a Hi-fi I dismantled.

I'm just looking for something really simple and easy to make- nothing fancy. Thats why I'm guessing distortion/ fuzz effects are my best bet.

I have:

• 2 input/output jacks
  
• 1 DPDT switch
  
• LM358n chip (its a dual op-amp)
  
• some random resistors
  
• random assortment of capacitors
  
• 1 meg pot
  
• wire
  
• 9V battery and clip
  
• 2 diodes
  
• a transistor of some description
  
• a few other random parts from the hifi, like relays etc.
  

Best thing I've found so far is this: http://www.montagar.com/~PATJ/mufffuzz.gif

The 4558 thing in that circuit is also a dual op-amp so I'm wondering if I could just use the lm358 as a substitute

anybody know if I can just substitute the chips?

or know of any other possible simple circuits?

Thanks!

[Ben]

I was just searching through the big hifi pcbs, checking to see if I have the parts to make the muff fuzz- and theres a 4558 chip on the board!

Looks like I have almost all the parts for the muff fuzz now!

(except theres a few cases where I'll need to use more than 1 cap/ resistor in series or parrallel to get the correct value)

I might just build the muff fuzz

I'll post the results if I do

[Paul Marossy]

Almost any standard dual opamp will sub for another. People notice the most difference in sound between a BJT opamp (like a JRC4558) and a JFET opamp (like a TL072). You can see the differenc on a scope, too. The BJT type opamps clip a little harsher than the JFET types do.

[Ben]

Thanks, I'll try both op amps and see which sounds best.

I have all the parts now except a few caps and resistors of the correct value. I could combine some to make equivalents- but I'm not totally sure that I dont already have what I need;

All the polarised caps are cylindical and have their value printed on them, but all the non polarised caps just have something like "102J" printed on them

How do I tell what value they are?

Google wasnt very helpful in helping me figure this out.

[Ben]

Get a load of my makeshift 470K resistor- made from 8 small resistors in series

[badsnap]

The 102J (don't know what the J means) is trasnlated as follows.....caps are listed in picofarads (.000000000001 is 1 picofarad) and it is common for the values to be listed in 2 digit format. So, the 10 means 10 picofarads and the 2 means to the second power (or 2 decimal places to the left). So your cap is .000000001 or 1 nanofarad.

Google "reading capacitor values" for a good list if this doesn't make sense. One of the site that pop up will be worded so you can understand. No offense meant, but I know I can read something on one site and not understand at all and then read the same information, presented differently, on another site and the lightbulb appears above my head...Rog

[Ben]

I'll look at the site, but I think I understood it when you described it.

It seems similar to the labeling resistors- maybe even simpler since it doesnt requre you to remember the colours.

Thanks!

I've nearly finished this thing already BTW- now I understand the caps I'll probably be done in about an hour or so.

Probably have to allow the usual 2 hours while I figure out why it wont work though

[Ben]

Probably have to allow the usual 2 hours while I figure out why it wont work though laugh.gif

Looks like that might be the case

I've pretty much finished it- and I just tested it....

No sound

However...

I've ommitted the 680k resistor between pin 3 and ground because I dont have one and couldnt be bothered to make another 8-resistor long chain right now

I'm intending to add the resistor later- I just fancied testing it. I was expecting at least *some* sound though...

• could the missing resistor explain the silence?
  
  • Also I replaced the 100k pot with a 1 meg one. I know its not ideal, but between 1 and 0 the 1 meg pot should be pretty much identical to the 100k- right?
    

  [*]If I just remove the 1 meg pot , would a 100k resistor be equivalant to having it set permenantly to full volume?

  Merci beaucoup

[Ben]

Finished it off.

I found out that the 9V battery I was using was dead Some fool had put a dead battery back in the pack (probably me actually)

Fingers crossed that it will work when I get a new 9V

[mammoth guitars]

The J in 102J is the capacitor tolerance, which in this case is +/- 5%. When caps have a number printed like 102J the 10 is the pico farad amount less the multiplier however this cap size will be refered to as .001uF. A cap marked as 104 is 100,000pF but will be refered to as a .1uF or .1 micro farad. For very small amounts it typically will be printed like 560pF which is 560 pico farad.