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Green Switch

Did its thing

The origin story: an Arduino lighting system, built as a teenager, that dims rooms by how much daylight is already there — good enough for ISEF.

✳ ISEF 2018 finalist · Embedded Systems ArduinoEmbedded 2018
✳ How it actually works
OUTSIDE · DAYLIGHT PHOTORESISTOR KNOB · WANTED LED fills only the gap LIGHT BUDGET WANTED = DAYLIGHT + LED daylight (free) led (paid) TARGET POWER DRAWN 0 W FULL at solar noon the LEDs barely sip the room asks only for what the sun can't give
FIG 1 · daylight does the heavy lifting — the LEDs fill only the gap
motion sensor someone walked in photoresistors how much daylight already? dimmer knob how bright you want it Arduino wanted − already there = what the bulbs must do LEDs driven with only the difference the next room over its spill-in light dims this one ↺ 2× the battery life of an ordinary LED dimmer built over two years of teenage evenings ISEF 2018 · Embedded Systems · booth EBED041 · the origin story
FIG 2 · the machinery — motion + daylight + your knob → just enough light
The story

Before the hackathons, before the degree: two years of teenage evenings learning Arduino to build a smarter light switch. Green Switch senses motion when someone enters a room, reads the ambient light with photoresistors, and compares it against the brightness you asked for on a dimmer knob.

The Arduino then drives the LEDs with only the difference — if daylight is doing half the work, the bulbs do the other half. Rooms even react to each other: light spilling in from next door dims the neighbours automatically. In testing it ran twice as long on a battery as an ordinary LED dimmer.

It went from the Hydro-Québec Montreal regional fair straight to Intel ISEF 2018 in Pittsburgh as a finalist in Embedded Systems, booth EBED041. The lab has been chasing that feeling ever since.

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