I have a dark pantry that needs more light, so I did what all makers do. That is, build my own instead of buying something simple. This board uses a magnetic reed switch as a door sensor. When the door is open, a relay completes the circuit and the light turns on. Because I'm using the available 120V AC, no batteries are needed. Keep in mind that this project uses high voltage and can seriously hurt you. Please don't try this project unless you know what you're doing.