Re: led dimmer circuit
- From: "mc" <look@xxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Sun, 4 Jun 2006 23:24:23 -0400
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.
Will someone explain *why* resistors "won't do the job"?
This is not a basic question. I am not the original poster. I understand
about PWM and its advantages (saving power). But if an op-amp adjustable
current source (which is not PWM) will do the job, surely so will a humble
rheostat.
Is there something strange about the current-vs-brightness relation of these
LEDs?
.
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