Arduino project · Light sensing · Medium
Light Keeper with a Set-Point Knob
Turn the knob to set the brightness you want in a room; the lamp switches on when the room is darker than that.
What you will learn
- What a set point is
- How to compare a sensor with a knob
- How thermostats and light controllers work
How it works
The lamp is full on while the light level is below the knob setting by at least 5, and off otherwise. The Compare step checks one sensor against another, so you do not need to set a fixed number.
Try this next
- Fade the lamp smoothly instead of on and off.
- Show the set point and the light on an LCD.
- Add a timer so it works only at night.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
Parts: sensors and actuators (tap to show or hide)
Try the inputs (virtual sensors)
Pins (you can change them)
| Part | Arduino pin (change it here) | How to wire it |
|---|
Every wire, one by one
Red rail = 5 V from the Arduino 5V pin. Black rail = GND. The coloured wires carry signals. Match the wire colours on the drawing to this list.
| # | Colour | From (part and leg) | To |
|---|
Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.
Quantities come from the parts you added. The store links open a search for that item on Robu.in, Amazon.in and ThinkRobotics, so you always see what is in stock today. Check the model, voltage and price before you order.
| # | Item | Qty | Search term | Buy / compare |
|---|
The PDF has the circuit sketch, pin table, every wire, sequence, full code, the parts list with store links, do’s and don’ts for each part, and the safety notes. The project file lets you come back and keep editing.
In the real world
A lamp you can dim
Your dimmable LED sets how bright the lamp in the real room glows.
Tip: use the gold tab at the bottom of the circuit drawing to pull the real-world view up over the Arduino board. Your parts stay visible above it, so you can press a button and watch the real scene react.
- Dimmable LED = the brightness of the lamp