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simple LED fade on / off

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mofotron

New Member
:shock:

Allo,

I'm pretty new to the world of circuitry, so please forgive me if this question has a rediculously simple answer:

is there and easy way to make an led fade on and then stay at a constant brightness until the circuit is broken? (it would also be nice if there were a way to make the light fade out when the circuit is broken)

If so, what parts should i use and can any of them control how long the fade lasts?

THanK you FOr youR tImE, i really appreciate any help i can get


- chip
 

bogdanfirst

New Member
hey Sebi, are you sure you have written correct? i think that is saw 10,000uF there......why couldn you use a transistor instead and a smaller value capacitor?
 

daviddoria

New Member
why do you even need a transistor? can't you just use like a 10uF cap? and again, is this called a choke circuit?
 

Phoenix

New Member
Would it not be better to put the capacitor across both the LED and the resistor? Reason being that once power is removed, you will get a large surge current through the LED if the resistor isn't there to limit the current drain, which could destroy the LED...
 

Sebi

Active Member
Phoenix, here cant flow higher discharge current as normal,because the LED -as zener - limiting the cap.voltage. If the capacitor prallel with supply,no fade-on effect...
 

john1

Active Member
cap has to be pretty large in that arrangement,
because the voltage drop to extinguish the led
is only a little below the lit voltage.

how about if the cap was at a slightly higher
voltage, but not supply voltage, which could
be considered to be grounded or near, after
switch-off.

This might allow a smaller cap to be used.
 

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