I admit it: I'm a total geek. I love electronics, programming, 3D art, vintage Apple hardware, and whisky. I'm always juggling half a dozen projects. I also enjoy documenting it all: my successes, my failures, my experiences... and everything geeky along the way.
I hooked up 24 LEDs to my Bare Bones Arduino just to see if 3 AA batteries would be enough to drive 24 LEDs.
Looks like it does a pretty good job of running them. I’m not going to need any transistors.
Here’s a video of it in action. (Again, not the final sketch. I need to make a lot more improvements to the color blending.)
Since I’m not going to need individual resistors on each LED, I can remove them from my PCB design. I’m going to just use one resistor for each of the RGB outputs coming from the ATmega. Since the LEDs aren’t going to sit flush with the boards, there’s no need to make the boards extend beyond the footprint of the LEDs. I was able to shrink the board down even smaller. I’ll save a little over $5 by trimming the boards down and eliminating the resistors.
I printed one out to get a good idea of the size. They’re tiny. They shouldn’t take up much space at all.
They’re looking pretty good. However, I was worried about not being able to cut them up with my Dremel without totally destroying them. Then it hit me, why don’t I just design the PCB as a single unit and just order 24 of them? Duh! I tried to squeeze 8 on a single PCB because I thought it would be cheaper. Not true. Ordering 3 boards with 8 LEDs on them costs $11.00, while ordering 24 boards with 1 LED each comes out to only $8.80. The best part is that I won’t have to cut them up!
I jumped back into Eagle and dropped the schematic down to one LED. I even rounded off the corners.
With this design I’ll not only save a ton of money, but I won’t have to cut them up either. Winning!