Uproar LEDs

[MattL]

Hi, I notice in the BOM for the Uproar, a blue diode is called for. There is no link for a place to source this, and I can't find it anywhere. I have the type that look clear when not lit up but turn blue when they do, however I've heard that these diodes don't work for clipping...I think because in some circuits the diodes light up and in some they don't. So the question is sort of twofold: is it true that the ones that only show color when they light up are not useful for clipping (not sure if that's what the blue one is for though) is it critical that it be blue (I've heard in many cases a color doesn't necessarily significantly change the sound), and I guess actually a third question if answers to these mattering are "yes", where can I get the blue glass ones?

[jkokura]

No, you can use clear diodes for clipping. They will work just fine. However, some people don't necessarily like the way they sound. I think that's a little silly, to not like them at all, but I do prefer the sound of the diffused diodes I typically use for clipping. It doesn't have to do with their colour at all though - it has to do with the physical properties the actual diodes themselves exhibit. Diffused LEDs just are different than clear ones. Colour doesn't indicate it so much as the actual forward voltage and ratings the diodes have. Different colours have different ratings, which is why some may sound different.

I typically use rectangular diffused diodes in either red, yellow or green. I can hear very, very, very minute differences between them. Usually I use them simply because it's fun to play with different colours. You'd hear more of a difference between say a red diffused and a blue clear, but the differences would likely not be as drastic as a Ge diode and an LED, or a MOSFET or the like.

I'll note as well that you can use any clipping device there with no problems. You do not have to use a blue one, or a clear LED at all. You can use a silicon or Ge diode there also. The reason a Blue diode is called for is that the original manufacturer of the pedal the Uproar project is based on used a blue LED. I do not know if it was clear or diffused, but I'd guess it was clear also.

Jacob

[culturejam]

What matters is the forward voltage drop. Blue water-clear LEDs have a pretty high drop. But anything in the neighborhood will sound about right.  (diffused LEDs have a much lower voltage drop)

http://www.mammothelectronics.com/4SLED5MMBL-p/1000-101-bl.htm

[MattL]

Thanks guys. that's good to know...word was on another site that you can't use them to clip. Since I can't see anything other than the clear/blue online, I'll assume that'll work. I also have red, yellow, and green. When I get to that point, I'll socket it and get back to you. Thanks again!

[culturejam]

word was on another site that you can't use them to clip.

The clear LEDs have a much higher voltage drop, so the signal needs to be higher than that (about 2v) before they will turn on and clip. So it is possible that in some circuits they wouldn't actually do anything.