Re: led dimmer circuit

On 6/4/06 6:41 AM, in article 1cCgg.4187$ED2.2097@xxxxxxxxxxxxxxxxxxxxxx,
"mc" <look@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

i would like a simple circuit that could be used to dim a high
brightness white led for installation inside a bird box for a colour
camera. i don't want to scare the birds by a simple on / off . A
gradule increase in brightness would be good. i have tried a resistor
in series followed by another variable resistor which works to a degree
but there comes a point when the brightness suddenly increases with a
small turn of the pot. could anyone post a simple cicuit please ?

The LED brightness depends on the current. It is easy to make a
voltage to current converter with an opamp:

http://www.allaboutcircuits.com/vol_3/chpt_8/7.html/conversion

But there should also be no problem using resistors. What resistances are
you using (fixed and variable) and is the variable one linear-taper or
audio-taper?



Resistors won't do the job. Post this on the basics board, or better yet,
google for led dimmer. You need a circuit that varies the length of time
the LED is fully powered, reducing it gradually to zero.

This has been answered a jillion.5 times.

.

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    (sci.electronics.design)