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Disclaimer: I’m an engineer, not a pro film maker. Be advised.

Disclaimer: I’m an engineer, not a pro film maker. Be advised.

 

 

This was a project in the making some years ago… See more about it here.

 

In this evening’s project, I want to evoke one of the most primal fears… eyes in the darkness.

 

It’s rooted in a real scary threat, some sort of wild animal. Rat, dog, flying squirrel, wolverine… whatever is the wild thing from where you’re from. Usually those eyes in the weeds/darkness are following by slow backing away or full blown running.

 

Just imagine, you’re alone in a forest. The evening is washing through the trees, dragging darkness with it. Before you know it, your vision shortens to half, maybe less of a distance in front of you. Light is almost gone. But there… somewhere between the foliage.. a pair of eyes appear. Maybe more. Maybe a whole lot more. The creatures of the forest are closing in. At least… that is the effect I was going for.

 

In this project, we are going to start out with one pair of eyes. I’ll show you how to add blinking for more realism. For the ambitious, I will show how to chain a bunch of eyes together for a greater effect.

 

 

The project by sections:

 

This project could easily be done without a microcontroller. Even the “blinking.” But, for a greater amount of control, I decided to use an Arduino Nano. It’s more about future proofing than anything, more this in the “If I had more time and money” section below.

 

The “eyes” are simply a pair of LEDs. I chose red for a classic evil monster look. I also use orange for a closer to an animal’s eyes in the darkness. However, any eye color is cool, I suppose. Perhaps blue for a “Game of Thrones” zombie.

 

I added a Light Dependent Resistor (LDR), or photoresistor, as a sensor for the Arduino Nano. I wanted to detect the ambient light conditions and turn on the “eyes” only when it is dark enough. Nothing ruins scary eyes like the daylight! As light disappears, the resistance of the LDR shoots through the roof, for those who are wondering. This is how the light level is detected, based on a resistance value.

 

In the circuit, I added a few potentiometers to adjust various aspects of the scary eyes. First, the brightness of the eyes – real eyes in the dark don’t look like a pair of headlights. The frequency of the blinking effect is also adjustable.

 

BOM:

1x Arduino Nano

1x Full-size breadboard

2x Small breadboards

1x Photoresistor

1x 10kOhm resistor

2x 1K Ohm resistor

4x 220 Ohm resistor

3x Potentiometer 100kOhm (I used these types, but you could use others)

2x NPN transistors (PN2222)

2 pairs of LEDs (Red)

Project wires

 

Schematic and design:

 

 

It is this simple. The complexity comes in the code.

 

This is the actual build. I strung an extra pair of eyes off of one of the mini breadboards - I stuffed the LEDs into a yarn ball. Also pictured is the 9V power supply I used to power it.

 

 

Code:

 

If you connect the Arduino to a PC, I put in an option to output serial data.

In the Scary Eyes project, I output the states of the three potentiometers. I label them as well, Threshold, Brightness level, and Blink duration.

 

 

Suggestions on the build:

 

You do not need to use breadboards for your “eyes.” You could just make a harness to string out the eyes where you see fit. Just run them back to the Arduino Nano.

 

I thought this system would be used indoors. Rain would be a huge issue to running it outside. Here are some suggestions about if you want to use this outside.

 

- First and foremost, run the system off of a battery to make it portable. The types you charge cell phones with would work.

- Put the Arduino Nano and its support components inside a water-tight enclosure with the battery.

- Run the cables outside the enclosure for the LEDs. This may require drilling and hot glue to seal the and potential leak points you create.

- Waterproofing the LEDs is the hard part. You could use a similar principle as the Nano’s enclosure. You could also put the LED inside a clear enclosure.

 

 

Other uses of the system:

 

- This is a prefect system to put inside the carved pumpkins. It will even turn on in the dark!

- You could also use them as eyes for the pumpkin too.

- Or, how about an overly complex nightlight?

 

Oddities and observations:

 

I found no real change in brightness when running off of a 5V USB connection. I didn’t string more than 3 sets of eyes though.

 

If I had more money/time:

 

- Originally, I wanted to add sound that would play as people approach the eyes. However, adding that would have cost too much in terms of logistics for the devices.

- My big plan for this was to make 100 pairs of eyes that would turn on in waves as people went through a wooded path. First a few, then a lot. Coupled with sound, that would be terrifying…. I thought.

 

Cabe

http://twitter.com/Cabe_Atwell