Model Lighting Circuit Help (LEDs)

Other Hardware General Electronics
1

Short version:
Playing with Arduino
Friend sees it, says "What's that?"
An hour or so later, says "So I have this model of the Enterprise (Star Trek), I wanna make it light up"
Me: "No problem" (ha!)

He says he'll handle 100% of the installation. Making LEDs fit, drilling holes, whatever.
I'm doing the programming and circuit design. I'm mostly a programmer with a bit of circuit design experience. I've seen Star Trek a handful of times as a kid, so I'm blindly going off what he says will look best.

http://imgur.com/5NrI4 -- Sketch (drawing) of what he wants

The white LED (center) is a "strobe". (It's an LED, but will look like a strobe from the code)
The rest of the LEDs will simply stay on (his specs). This means the arduino would only be used for blinking one LED.
The port/starboard lights will have to be 3mm LEDs, due to physical constraints of the model.

I want to:
Make the blue engine lights (white box) fade from, say 100-90% brightness.
Blue warp speed(?) lights (blue box) - I talked with him about using an RGB LED to change colors.

My questions:

  1. This is too much power to simply use the Arduino I/O pins, right? (External power/transistor switching?)

  2. All these different colors are giving me a headache trying to find the most efficient way of wiring everything together. Any thoughts?

2 - Info) I have almost no specs on these LED's. He wants to pick the stuff up from RadioShack in one trip, and doesn't want to wait for an online order. Their specs are all over the place online, and comments show that the specs on the site often don't match the specs of the actual product. My plan is to just buy them as close together in voltage/mA as possible, then calculate resistors.

  1. Thoughts on (cheap) fiber optic solutions? I've never used fiber optics before - can I just fit the fiber to an LED, or do I need an actual fiber optic light supply box?

Thanks!

p.s. I know it's a waste of $35 to blink one LED. He's okay with that, because the lighted model is much more expensive. (Also why I want to make some of the other lights glow/flicker). Any creative tips/ideas would be appreciated, because I'm not familiar with Star Trek nor model lighting. I write code..lol

2

For most leds witht the supply voltage at 5v any resistor from 220 to 1k ohms will work, and. If you have less than 18 leds total you wont need any transistors so long as you stay to one led per pin, or use a transistor for say a couple leds in parallel(or series with higher voltage)
why not add sounds too? A little speaker with a transistor and you can make some cool old 8bit type sounds to match the leds
The uno has a limited amount of pwm pins so you will only have so many dimmable led "channels" ,

3

If you limit the max current per pin to 25mA and the total current from all pins to 150mA then you'll be safely within the maximum specs of the Arduino. One or two LEDs per pin with suitable current-limiting resistors should be fine. You have 6 PWM pins to play with which sees plenty for this project.

4

Awesome, so this isn't nearly as complicated as I was making it out to be in my mind.. lol

5

You can use an Uno to program an ATTiny85 ($1) and have 5 pins (2PWM*) for I/O, or an ATTiny84 ($2) for a few more. If you have any intention of doing this with more models in the future this is the route you should take to save money.

  • You can use software PWM or a supporting chip like the TLC5940 for more pins but that's a more advanced topic.