Hi, I'm somewhat of a newb, so any help would be appreciated.

I'm trying to use PWM to control the brightness of some Blue LED's (about 8 of them) in my car.

I've set up a 555 timer circuit on a breadboard using this schematic:

http://picasaweb.google.com/lh/photo/HVYSSHYf-H8yNNP5jVTiPA?feat=directlink

I've replaced the 10k resistor with a 50k log potentiometer to control the brightness.
It works, but I'm not really happy with the control with the pot. The lights dim quickly during the last ~10-20% of the pot's rotation, and from ~20%--100%, the LEDs stay at full brightness. Is there any way I can modify this circuit to get better control?

What I'd like is for the potentiometer's turn to control the brightness more precisely.

Thanks!

 

Hello,

Just take a look at this thread of SgtWookie:
http://forum.allaboutcircuits.com/showthread.php?t=9016

Greetings,
Bertus

 

I've also got a work in progress that might apply.

555 PWM Oscillator

 

Try this circuit.

It's basically the same circuit that Bertus posted a link to, but I like using the extra 3 nand gates in parallel to drive the FET with, it switches better.