Driving LED's with PWM

[Demon]

...Another thing that doesn't make sense is the non-linear curve in current when adding diodes onto the PCB. One LED consumes 30mA but two doesn't equal 60.

I have a similar problem. I'm designing panels for my residential alarm system and I'm kinda overwhelmed by the possible maximum current. A LOT of LEDs could potentially be on at the same time (I'm using solid strand 24 AWG telephone wire with 12V 7Ah battery backup).

I started with LCDs, but these panels are not only for the house where it's warm, it's also for the garage (worried about cold and humidity).

Robert

[mackrackit]

A little crap to wade through.. but these two threads might help.
http://www.picbasic.co.uk/forum/show...egment+display
http://www.picbasic.co.uk/forum/showthread.php?t=3510

[Demon]

Thanks!

Just went through the 1st, great stuff!

Didn't download the dice yet. I want to see what I can do on my own first.

Robert The Very Happy Camper

[Christopher4187]

I have a similar problem. I'm designing panels for my residential alarm system and I'm kinda overwhelmed by the possible maximum current. A LOT of LEDs could potentially be on at the same time (I'm using solid strand 24 AWG telephone wire with 12V 7Ah battery backup).

I started with LCDs, but these panels are not only for the house where it's warm, it's also for the garage (worried about cold and humidity).

Robert

If it's a panel inside then you could supply 1-3mA per LED. There's no reason to supply the maximum amount of current since you won't have an audience to view them and they are inside. I recently used Screenmaster LED's and at 1mA they were really bright. I wish I had your problem. My LED scoreboard is outside and the sunlight hits it. Needless to say the LED's have to be really bright.

[Demon]

If it's a panel inside then you could supply 1-3mA per LED. There's no reason to supply the maximum amount of current since you won't have an audience to view them and they are inside. ...

I'll be using surface-mount LEDs that I have on hand (got some greens, yellows and reds). I think they require somewhere between 15-20mA to be reasonably visible in daylight inside the house (some panels could be in full sunlight).

I'll be making my own light chimneys with clear liquid plastic from Smooth-On.

Finished preliminary testing today, very low current is achievable, I just have to improve code logic and efficiency:
http://www.picbasic.co.uk/forum/showthread.php?t=18906

Of course none of the colours I have are of the same brightness so some tweaking of the resistors will be necessary.

Robert