Quick'n'easy Fireplace for Nativity Scene (presepe)

Ok, you're almost ready for Christmas, your tree is up, and your Nativity scene is in place but it looks too static, isn't it? Yeah, you tried by putting some flashing Christmas lights in it, but now it looks like a "disco pub" instead of a nativity place...So this is a "quick'n'simple" solution to get some real life in it!

Put a "live" fireplace inside it, you just need 15 minutes to build and put in place!

You only need:

1. 1x Arduino (I used a One but smaller Nano could be the best choice)
2. 3x LEDs: red, yellow, blue
3. 3x 220 Ohm resistors
4. A few proto board wires

Circuit is pretty straightforward, just connect the LEDs (with each resistor) to Arduino: red and yellow one (the "fireplace") to PWM 10 and 11 outputs, blue (the "celestial light" ;-)) goes directly to +5V to let it on all the time.

I used a small breadboard shield to make it easier to connect everything, but you could choose different solutions.

Please note wires should be long enough to reach the place: if you put Arduino behind the cave, 30-40 cm are enough. Just to make it simple, I used a few male-female 20 cm Dupont wires, as shown on the above picture, connected in chain just to get a length of 40 cm.

Now load Arduino with the code "Fireplace.ino" and you're ready to give your Nativity a bit of "real light"!

For more "technical" details, as you can see from the sketch the program simply creates a "fireplace light simulation" by turning red/yellow LEDs on, with random bright and random delay. Brightness levels and durations have been "tuned" to let the effect more realistic keeping yellow LED level a bit more higher than red one and sometimes turning red completely off.

Put red and yellow LEDs inside the cave and behind the figures and cover them with some straw. Better results are achieved by putting something as a white diffusor shield over the LEDs and under the straw (e.g. a small piece of white plastic). Then put blue LED somewhere on the top of the cave, to have a dim blue light over the figures.

Final result should be similar to the one shown on the top video!

Have a nice Christmas!