LED/LDR Question for optical trems & compressors

[Kroars]

Hello all,

Ive got a couple questions regarding the LED’s that pair up with LDR’s in these circuits.

1. Is diffused better than water clear? Does it depend on the circuit?

2. Is there a difference between 3mm & 5mm? I find that when I build a Vactrol it’s a better fit (for me anyway) using a 5mm in conjunction with the LDR in the shrink tubing as they’re closer in diameter than the 3mm’s.

Thanks!

 

[Chas Grant]

I wondered the same thing about the diffused and clear before, honestly there is no right answer. Some people prefer the diffused and some the water clear. Then there is always the discussion of which color. What it really boils down to is your own preference. I personally prefer the the yellow diffused LED's. I have tried others, these just seem to work the best. For the size go with the 5mm, as you stated they fit the best.

 

[Kroars]

I wondered the same thing about the diffused and clear before, honestly there is no right answer. Some people prefer the diffused and some the water clear. Then there is always the discussion of which color. What it really boils down to is your own preference. I personally prefer the the yellow diffused LED's. I have tried others, these just seem to work the best. For the size go with the 5mm, as you stated they fit the best.

Thank you good sir!

 

[Dreamlands]

This is the spectral response curve of the KE-10720 LDR:



In this case, a yellow LED is a good fit to maximize the response:

 

[Chas Grant]

This is the spectral response curve of the KE-10720 LDR:

View attachment 7760

In this case, a yellow LED is a good fit to maximize the response:

View attachment 7761

Thank You, I usually use the 10720 LDR so that would explain why the yellow works best and the green wasn't to bad either.