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-   -   wiring led on power switch (http://www.diyaudio.com/forums/tubelab/228365-wiring-led-power-switch.html)

rock12 21st January 2013 11:57 PM

wiring led on power switch
 
my power switch has a 2.4volt led ?millivolts I was thinking of using the 6.3voltac off the heater line using a ln400x diode to a 10uf in parallel then a 2k resistor. I heard that the cap removes flicker in the light. do these values sound usable

gootee 22nd January 2013 02:43 AM

You might want a larger capacitor value. I would probably start with something like 100 uF. It really depends on the average current draw. More current would mean more ripple amplitude.

How much current do you want through the LED? A 2kOhm resistor won't give you much; maybe around 1.5 mA average. Something like 330 Ohms might give about 8 ma average.

With 2k and 1.5 mA, the 10 uF cap would give about 50 mV ripple, peak-to-peak, out of about 2.5 V across the LED. That should be fine, I guess.

But if you need more current, you can increase the cap value proportionately if you don't want more ripple amplitude.

DUG 22nd January 2013 03:54 AM

If you use a full wave bridge the "flicker" frequency will be 120Hz

You will not notice it.

R between 330R and 499R...depends on LED and how bright you want it.

acceler8 22nd January 2013 04:17 PM

http://static.diyaudio.com/forums/ga...a/1761/LED.JPG

This image may help. I assembled the cap and diode first. I then tested the voltage and calculated the resistor from that. I notice no flicker at all.

rknize 22nd January 2013 05:08 PM

If you move the cap to the other side of the resistor, it will work even better (fwiw).

KatieandDad 22nd January 2013 05:13 PM

Generally the human eye doesn't notice anything above 25Hz - TVs and flourescent lighting are a testament to that.

rknize 22nd January 2013 07:47 PM

It depends on how fast the LED is. TVs have rather slow phosphorous and don't toggle from on to off on every refresh. :) Some people get headaches from slow computer monitors.

I've used LEDs in situations like this where the flicker is noticeable, especially when sweeping my eyes across the room. Anyhoo...if you don't notice the flicker it's not a problem.

tinitus 22nd January 2013 07:51 PM

subject is interesting enough on its own, but sorry, if I don't understand .....since its a tube amp, won't the tubes tell you when its on :scratch2: :D

Frank Berry 22nd January 2013 07:57 PM

Quote:

Originally Posted by tinitus (Post 3337876)
subject is interesting enough on its own, but sorry, if I don't understand .....since its a tube amp, won't the tubes tell you when its on :scratch2: :D

Now that just makes too much sense.

rknize 22nd January 2013 08:34 PM

Quote:

Originally Posted by tinitus (Post 3337876)
subject is interesting enough on its own, but sorry, if I don't understand .....since its a tube amp, won't the tubes tell you when its on :scratch2: :D

Only a few of them glow blue...


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