Dimming LEDs by changing voltage or current is a black art.
Black art.
Um. LEDs are diodes.
Now you need an active component in addition: a triangle wave generator. You can find a circuit by clicking I'm feeling lucky on Google with the phrase triangle-wave generator circuit.
The third link under 'LED dimmer' which goes to Mike's flight deck has both the theory and the circuit of LED dimming.
Good luck.
BAJ
Dear All, I am currently building an art project but cannot seem to get my LED's to dim properly. I have tried capacitors but to no avail. I've heard that diodes could dim the LED's but I would like the lights to dim slowly on and off. Thanks for any tips.
Simon Griffiths.
One way is to PWM the LEDs, with the modulation rate being at or above
60-80Hz.Jon
Go here:
Ed
LED dimming by current control (analog) is hardly a black art. For simple dimming, a voltage controlled current source with sufficient compliance would work fine.
The top of page 12 of this shows a bilateral current source which would work if you limited your control voltage to the correct polarity.
5 years ago I did a prototype linear LED controller using a now discontinued Burr-Brown SHC615 driving the LED and sourced with 15KHz to 30MHz analog video to test photosensor/preamp assemblies. It worked very well.You can do this with one opamp.
GG
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