dimming LED

[Guest valkr1e]

anyone have any ideas on how to make a dimming LED flasher or just via a knob or something, IE the LFO LEDs on the virus, or what have you.  I am primarily concerned with how to make the LED dim since creating a controlling circuit wouldnt be too difficult.

[TK.]

normaly a pulse wide modulated signal is used to dim a LED. The principle in a nutshell: with shorter pulses (___||____||____||____||___) the effective power through the LED and therefore the illumination is lower than with longer pulses (_|   |_|   |_|   |_|   |_).

Diming some LEDs was the very first project I realized with a microcontroller. It was a 80c535, a little bit overkilled for such an application, but it worked well ;-) It can be realized much easier with PIC micros, since most of them contain one or two PWM units

Best Regards, Thorsten.

[Duggle]

Adjusting the pulse width is ideal for controlling brightness dynamically with a digital circuit, as Thorsten says. If the "controlling circuit" is an analog waveform generator(eg LFO) then the brightness of the led will be proportional to the LED current. This is easily measured by looking at the voltage across the LEDs series resistor.

For a standard LED the voltage source must be above 1.2V before any current will flow above this brightness and voltage will be quite linear.

questions welcome. ??? -> :D

[Guest valkr1e]

i have many questions about this, but it's 1:30 am here and i'm in the middle of an emergency file recovery(i just lost 10,000 emails on accident, oops! silly me)

when i get a chance tomorrow or thursday, i'll ask