Arduino project · Motion and security · Easy
Intruder Alert with PIR Sensor
When the PIR sees movement, a red light comes on and the buzzer beeps twice.
What you will learn
- How a PIR sensor detects heat from people
- How to wait for a sensor event
- How to build an alarm sequence
How it works
The Arduino waits until the PIR output goes HIGH. Then it lights the red LED, beeps the buzzer twice and keeps the LED on for 3 seconds before switching it off and waiting again.
Try this next
- Make the alarm keep sounding until a button is pressed.
- Add a second PIR for another room.
- Add a relay to switch on a lamp as well.
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 room with a burglar alarm
Switch the motion sensor on in the simulator. A person walks into the real room and the alarm bell rings with a flashing beacon.
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.
- PIR sensor = a person moving in the room
- Buzzer = the alarm bell
- Red LED = the warning beacon