Building Your Project

Blinky eyes may be placed into nearly anything. That is most of the fun in this project. Select where you would like to put them then build the appropriate lighted eyes, put them in and you have a complete project ready to go.

For my project, I went to that staple of American shopping experiences: Walmart. There in the Halloween section is the 97 cent box. I found an assortment of small sippy cups crying to be liberated from their straws and modded to be small, scary light sensitive balls of evil. You may chose to place the eyes into any item or even a board to hide in a window or the bushes.
Removing the straws, I drill small holes in the eyes then use a larger 5 mm but to size the holes the same as the LEDs I chose. The hole in the top where the straw was will serve as the place the photocell will be mounted to detect whether it is dark enough to turn on the eyes.

I placed the photocell and LEDs on the ends of male to female jumper wires. Any hookup wire will do, but the jumper wires hook right in to my breadboard and the components. You will want to trim the component leads a bit before placing in the female end to avoid the wires touching and shorting out.

Put the batteries in the holder and for Trinket plug into the breadboard with the red lead to the BAT+, the black to GND. If you use Gemma, plug the battery holder JST (white) connector into the Gemma battery socket. Lower the board into your selected container and thread the LEDs into the eye holes. If you want, a dab of glue will hold the LEDs in place. Thread the photocell through a hole in the top and secure with tape, Sugru, or other substance being careful not to twist the wires or make them touch.

Turn on the curcuit and put the lid on. Now when it is dark enough, the lights will fade in and out and "blink" (go on and off quickly). Enjoy your scary eyes project.

Low Light Sensitivity

If you find the photocell sensitivity too high or low (which may vary due to the cell's characteristics or the actual value of the 1K resistor), change the value of SENSITIVITY near the top of the code. Valid numbers are zero to 1023, you will want to select a number from about 150 to 800. The lower the number, the darker it must be.
This guide was first published on Oct 30, 2013. It was last updated on Oct 30, 2013. This page (Building Your Project) was last updated on Jun 06, 2019.