LEDs

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Tomo

Member
2002-06-18 9:54 pm
Hello,

I was experimenting with old LED schematics where I ran LED off of outlet.

(AC)-C-|>|-R-(AC)

C=0.1uF
R=120 ohms

It used to be 0.47uF which was too bright so I toned down. What I am wondering is that in JED's post, he uses another LED connected parallelly but in opposited direction. I did not have LED so I used a rectifier but LED did not light up. ... so I left as above.

I think it is bad since C must charge at breakdown region of LED (beyond reverse bias). I know it's ok to swing Vdiode all over the place as long as I don't blow them, but I am not sure in this application.

Thanks in advance,

Tomo
 

Tomo

Member
2002-06-18 9:54 pm
Hey,

I gave up and use two LEDs now. I can't get it to work with 1N914A as shown by the schematics here.

http://www.diyaudio.com/forums/show...44&perpage=15&highlight=blue led&pagenumber=2

I dunno why, it doesn't work. But then dual LED trick is a neat one. Kinda helps me to remind myself my tranny is powered. Also, the fact that brightness is controlled by the capacitance is kinda neat.

Also, I think this installation is effectively external to the amp. So I think it effects audio very little. But it cycles so it shouldn't be used for something like Peter's Blue LED trick with CDP(???).

Thanks anyways,

Tomo

P.S. If you gotta cooler trick, teach me!?
 

Tomo

Member
2002-06-18 9:54 pm
Hello,

I think dual LED (or LED-1N914 if it works), keeps LEDs in forward bias (or cutoff) region. Is this correct?

Where am I going at? Well, I am wondering if I need to protect the module. But then if above is true, the LED won't see anything but the threshold voltage. (???)

Another question, what does changing R value do? I think it controls the discharging time. Can it be longer than 1/60 sec? I think flickering can be reduced. (???) But probably voltage drop across the R will be bigger.

Thanks,

Tomo
 
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