dimmable LED control board

[Todamont]

Hi. I'm making a stained-glass peice for a friend and I'd like to have around 500 LED lights set behind it, controlled to light / dim / off in predefined sequences with a standalone PIC control board, powered by a 5V supply. I have a BS in computer engineering, but it's been a while since I did any hands-on electronics projects... Programming the PIC is not an issue, I know how to do that part.

I'm looking for a driver board (or just a component) with transistors that I could drive with the PIC to supply power to the lights. As I said, it needs to be standalone, so my buddy can just turn on the power and use a simple switch to choose between maybe 3 display patterns. I probably only really need 8 "channels", dimming would be a great feature. Is there an IC just filled with FETs that would handle powering say 80 LEDs on each pin? Could anyone recommend a schematic with minimal components? Suggestions would be greatly appreciated~

Ryan

[sahu]

Originally Posted by Todamont

Hi. I'm making a stained-glass peice for a friend and I'd like to have around 500 LED lights set behind it, controlled to light / dim / off in predefined sequences with a standalone PIC control board, powered by a 5V supply. I have a BS in computer engineering, but it's been a while since I did any hands-on electronics projects... Programming the PIC is not an issue, I know how to do that part.

I'm looking for a driver board (or just a component) with transistors that I could drive with the PIC to supply power to the lights. As I said, it needs to be standalone, so my buddy can just turn on the power and use a simple switch to choose between maybe 3 display patterns. I probably only really need 8 "channels", dimming would be a great feature. Is there an IC just filled with FETs that would handle powering say 80 LEDs on each pin? Could anyone recommend a schematic with minimal components? Suggestions would be greatly appreciated~

Ryan

i think it usefull for u ...http://hobby_elec.piclist.com/e_pic6_b.htm

engoy with it.........

[Todamont]

Thanks for the info! So if I want, say 20 lights to be controlled by each pin on the PIC, should I just string them up in parallel (replacing the single LED in the diagram with 20 LEDs in parallel)?

I'm figuring a max draw of 1A gives me about 50 LEDS on at a time (at 20mA per), or two strings on full, one dimmed. I suppose I should try to find a 3 terminal regulator that can source 1A at 5v (5 watts at a time)? Maybe I can find some LEDs that will be bright enough to illuminate the glass well at like 2 or 3 volts.

Again, I greatly appreciate the help of the forum members~

[geko]

Originally Posted by Todamont

Thanks for the info. So if I want, say 50 lights to be controlled by each pin on the PIC, should I just string them up in parallel (replacing the single LED in the diagram with 50 LEDs in parallel)?

Try this site for help in designing the LED array
LED series parallel array wizard

All you then need is a MOSFET(s) to drive the array. Something like that used on this PWM driver Power MOSFET RGB LED PWM