Flatline LED brightness

tech9_79 · October 21, 2009, 12:33:00 PM

Just finished a flatline with a home rolled led/ldr.

ldr 10k/5meg light/dark and a kingbright 3mm yellow led.

Everything seems to working correctly but i have one question.
The led seems to max out at only 20% brightness and only lights up when strong power chords are played.

Is this normal?

idiot savant · October 21, 2009, 07:47:10 PM

I believe the led should increase in intensity as the notes fade out. So without playing, it should be full on. As you play -harder-louder- the led should decrease in intensity.

petemoore · October 22, 2009, 01:41:08 AM

The led seems to max out at only 20% brightness and only lights up when strong power chords are played.
Could be you only need that much, and more will of course change the response.
Brightness is a function of the LED type [super bright ? regular ?] and the amount of current going through it, there's probably a current setting resistor ?

oldrocker · October 22, 2009, 05:49:48 AM

Actually the LED is off until the input signal is applied. The harder attack the brighter the LED gets. As the led fades out the volume increases. Correct me if I'm wrong but that's how mine is set up I believe.

idiot savant · October 22, 2009, 06:19:25 AM

Quote from: idiot savant on October 21, 2009, 07:47:10 PM
I believe the led should increase in intensity as the notes fade out. So without playing, it should be full on. As you play -harder-louder- the led should decrease in intensity.

whoops, strike that...reverse it.

Quote from: oldrocker on October 22, 2009, 05:49:48 AM
Actually the LED is off until the input signal is applied. The harder attack the brighter the LED gets. As the led fades out the volume increases. Correct me if I'm wrong but that's how mine is set up I believe.

yep you're right, I opened mine up to verify.

tech9_79 · October 23, 2009, 04:40:09 PM

did you by chance see how bright the led was while playing? my led doesn't even light up on single notes

oldrocker · October 23, 2009, 05:54:13 PM

The LED should light with single notes easy. So I assume something is wrong with your build.

tech9_79 · October 24, 2009, 11:28:07 AM

Quote from: oldrocker on October 23, 2009, 05:54:13 PM
The LED should light with single notes easy. So I assume something is wrong with your build.

thanks man thats what i needed to know, im thinking somethings up with the germ diodes, 2 of them just feel apart in my hands when i bent the leads.

im all out except for Si diodes, anything at ratshack i can use? Schottky?

petemoore · October 24, 2009, 11:36:11 AM

any old GE transistors around there ?
The B/E is a diode.

oldrocker · October 24, 2009, 04:48:49 PM

I don't believe SI diodes will work. Was the ge diodes 1n34a's that broke? I don't know if 1N400x diodes will work. You might have to order them online.

tech9_79 · October 25, 2009, 11:30:22 PM

Quote from: oldrocker on October 24, 2009, 04:48:49 PM
I don't believe SI diodes will work. Was the ge diodes 1n34a's that broke? I don't know if 1N400x diodes will work. You might have to order them online.

yeah 1n34a, isnt it all about the forward voltage? is there anything new production that can replace a ge diode?

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Flatline LED brightness