Would you like some spooky glowing eyes that light up and play a sound when someone gets near? This circuit makes it pretty simple. It uses a single phototransistor to detect someones presence. Instead of having a preset threshold that needs to be met, it simply triggers any time there is a sufficient change in the amount of light it detects. If you put one of these in a nice dark spot, your halloweeners will only see the LEDs and perceive them as eyes. It might also be cool to somehow add motion to this.
We’re running out of time to prepare for Halloween, don’t forget to send in your projects.