Adding LEDs

To create the LED stars and Rudolph's nose, we will use copper tape and make a parallel circuit. A parallel circuit allows all leds to have the same voltage applied across but current will be different. A series circuit would work too, but a parallel circuit works better for the layout of the LEDs and the copper tape.

If you're curious about the science behind circuits and want to explore further, check out the guide: Circuits from Scratch.

Mapping out the circuit and adding copper tape

  • Cut out a 17 cm x 24 cm sized piece of black construction paper.
     
  • Glue it to front of diorama.
     
  • Draw with pencil where stars and moon should be placed.
     
  • Make the marks in the same locations on the back of the diorama. (I glued a piece of white paper to the back to make it easier to see the circuit).
     
  • Draw a line for POWER (3.3V) from the bottom right to the top left. Mark space for the resistor shortly after line begins.
     
  • Draw a line for GND from the bottom right to under the bottom side of the LED marks.
     
  • With copper tape, place down along lines leaving space for the resistor. The less you cut the tape, the more conductive it will be. When reaching a corner, instead of cutting then starting the tape again, try folding.
     
  • Cut out the moon.

Add the LEDs!

  • Stick the white LEDs through the holes from the front of the diorama.
     
  • Orient the LEDs such that the longer leg (the positive lead) is facing up.
     
  • Use more copper tape to tape down the LEDs with legs that reach the tape.
     
  • Bend the legs of the LEDs that are sticking over the tape such that they align with the tape. Tape LEDs down.
     
  • For the legs that don't reach tape, add some tape to an existing line of tape, tape down the LEDs.
     
  • Tape down the resistor.

*The LED legs need to be sandwiched in between copper tape in order to access power from the CPX.

Rudolph's red nose

  • Poke a hole for Rudolph's nose.
     
  • Stick a red LED through hole.
     
  • Add copper tape to back of the front leg and the upper back.
     
  • Bend LED legs so the longer (positive lead) is aligned with upper back tape and negative lead aligned with front leg tape.
     
  • Using two black jumper wires or black ribbon cables, tape down one end of one wire to each LED leg.
     
  • Pull the other ends of the cables through the moon hole and tape the positive lead to positive line of tape and negative to negative line.

Adding power and ground

  • With black and red alligator clips, attach to GND and 3.3v on CPX then tape down the other ends to back of diorama in designated areas.
     
  • Plug in power to CRICKIT and, hopefully, watch the lights turn on!

Troubleshooting the LEDs

If some lights are on and others are not:

  • Double check the orientation of the LED legs. The longer legs should be connected to power.

If the white LEDs turn on but the red one doesn't (or vice versa):

  • Try removing the resistor and putting copper tape down in its place. Not all LEDs may be getting enough current.

If all else fails, the more copper tape you add to meager looking areas, the more conductivity you will have.

Capacitive touch moon

  • Take some aluminum foil and the moon we cut out earlier.
     
  • Wrap the moon in the foil.
     
  • Glue the moon in place with the extra foil coming out of the back.
     
  • Attach an alligator clip to the foil and the other end to A3 on the CPX.
     
  • Screw in the DC motor to the CPX.
  • Glue a skewer to the back to hold the diorama upright.

Power up CRICKIT, touch the moon, and watch them ride!

This guide was first published on Dec 03, 2018. It was last updated on 2018-12-03 19:34:27 -0500. This page (Adding LEDs) was last updated on Dec 03, 2018.