Diodes: My FAQ

[Dolmetscher007]

The Peda I am building requires three diodes:

D1 -- 1N4004 -- DO-41 Package
D2 -- 1n4148 -- DO-35 Package  *experiment*
D3 -- 1n4148 -- DO-35 Package  *experiment*

I tried to find the 1N4004, and it brings up a multitude of results. I have decided to go with DigiKey for sourcing all of my components, at least at first. My plan is to get all of my components on the BOM sourced on DigiKey, added to a Cart, and then I will go to Small Bear, and maybe Mouser or Newark, and create a cart at each of those sites too, so that I can get a good feel for how widely parts can vary in tolerance, price, and whatever else.  So...

When I go to find the 1N4004, just by searching on: 1N4004  on the DigiKey website, it returns two results, neither of which are in stock. I was able to find it with a Google search in several other places. So, I took the values that I was able to find from the other websites... go back to DigiKey, and looked under discrete semiconductor > diodes, and when I filtered on 400V,  1A, and DO-41, I found a long list of 1N4004's. They just all have other letters at the end.

• 1N4004-TP
• 1N4004-G
• 1N4004G-T
• 1N4004G
• 1N4004RLG
• 1N4004GP-TP

I don't know if this link will work or not, but here is a "share it" link from DigiKey for all the search results that I was able to narrow down: https://www.digikey.com/short/pczhdh

As you can see (I hope), there are several values that do vary across these six different search results.

• Voltage - Forward (Vf) (Max) @ If
• Reverse Recovery Time (trr)
• Current - Reverse Leakage @ Vr
• Capacitance @ Vr, F

Can anyone clue me in on what matters with diodes for this design:
http://permanentelectronics.com/DIY/P.E.CSSTB.rev1/P.E._Colorsound.Supa.rev1.pdf
http://permanentelectronics.com/DIY/P.E.CSSTB.rev1/P.E._Colorsound.Supa.rev1.BOM.pdf

And what is up with the *experiment* bit on the BOM?

[thermionix]

-TP seems to refer to "tape" packaging, used for machinery that stuffs components onto boards, irrelevant for DIY pedal building.  I didn't look at the other suffixes, but as long as you're looking at through-hole 1N4004 diodes, it won't matter, get the cheapest.

A better idea is to buy a bunch of 1N4007 diodes, and use them anywhere a circuit calls for a 1N400_, they are rated for 1000V instead of 400V, perform the same in pedal circuits, and are the same price in most cases.  Then you also have tube amp rectifier diodes should you ever need them.

D2 and D3 are likely clipping diodes.  You can use almost any type of diode, even LEDs, in various combinations, to alter the character of the clipping (distortion).  That's why they say to experiment.  Generally speaking, you need at least one diode pointing in each direction, other than that it's whatever sounds best to you.

[GibsonGM]

DEFINITELY try some LEDs in clipping circuits   

[Dolmetscher007]

I hate to admit this... but it looks like i'm going to have to just come right out and say... I don't have a grasp on how caps, resisters, diodes, and transistors change the sound of a guitar.

I am looking at this schematic, and I see where the signal comes in from the guitar... goes through some resisters and some capacitors, hits a transistor, goes through some more resisters and caps, some diodes... and right now, while I DO know what each of these components does... I don't know how they work together to make... Fuzz.

Some resist current, some store it and release it, some amplify it... but while I can find a ton of videos on YouTube that walk you through how a tube amplifier works, I can't find ANY videos on how distortion works. There are theoretical videos that show what soft clipping, hard clipping, etc are... and there are videos on how to solder components onto a board to make a pedal... but I can't find anyone who makes videos that say...

"The guitar signal comes in and goes through a  1MOhm resister... What that does is... and then it passes through a .1uF cap, and that takes the signal and..."


Anyone know of any videos like that?

[PRR]

> videos on how distortion works.

Put a kitten in a bottle. Feed it. You get a distorted cat.



Drive a 8 foot wide truck through a 6 foot wide garage door. You get a distorted truck (or garage).

Amplify a signal bigger than the power rails (or diode clippers). You get a distorted signal.

[thermionix]

(pu$$y in a cok jar?)

[Dolmetscher007]

Man... I LOVE Radiohead!!!