Motion Event Alarm Kit

Classes 9-10, typical ages 14–16. Age ranges vary by learner. Guided low-voltage electronics.

Activity engagement

60–90 minutes. Explore 10–15 min · Build 20–30 min · Test and discuss 30–45 min. Estimated time for building, testing and discussion.

What you need

A computer with a USB port and Arduino IDE is required and is not included.

Included components

• Small Breadboard / Mini Solderless Board - 400 points — 1 breadboard
• Jumper Wire Combo - Male to Male, Male to Female and Female to Female Breadboard Connecting Wires (10 Qty Each) — 1 set
• Illustrated Activity Guide and Observation Sheets — 1 set
• Fitted Headers and Labelled Connection Leads — 1 set
• Arduino Uno R3 CH340G version compatible Arduino Development Board — 1 controller board
• USB A to B Programming Cable for Arduino Uno/ Arduino Mega — 1 data cable
• HC-SR501 PIR Motion Sensor Module — 1 sensor module
• Small Piezoelectric Buzzer - 5V Passive Buzzer — 1 piezo sounder

What you learn

• PIR detects changes in infrared patterns rather than measuring distance.
• Sensor warm-up and output hold time affect behaviour.
• Edge detection avoids logging the same held output repeatedly.

Connection guide

• HC-SR501 VCC → 5 V; GND → GND; OUT → D2.
• Passive piezo + → D9; − → GND.

Steps to make it

1. Disconnect all power and identify the supplied part labels and pinouts before wiring.
2. Set the PIR delay low and identify its retrigger jumper using the supplied card.
3. Upload and leave the sensor stationary for at least 60 seconds to settle.
4. Walk across its field of view, then compare moving directly toward it.
5. Record five event timestamps and compare stillness with movement.
6. Change only the named parameter for the extension, repeat the controlled trials, save observations and disconnect power afterward.

Programming resources

Arduino IDE: select Arduino Uno and the USB port. Use the supplied USB data cable. Serial Monitor/Plotter: 115200 baud.

Uses the selected board core libraries.

Download starter sketch

Test challenge

Does the sketch report one event per LOW-to-HIGH transition, rather than every loop?

Observation task

Movement direction, sensor setting, event time and observed output hold length.

Expected result

A rising PIR output prints an event time and starts a tone; a LOW output stops it.

If it does not work

Allow warm-up, avoid moving the board and inspect the delay/retrigger settings. PIR is not a reliable occupancy or life-safety detector.

Try next

Replace the continuous tone with a brief non-blocking event beep.

Use and supervision

Use only the supplied low-voltage DC parts. Disconnect power before rewiring; check polarity and labelled pinouts. No soldering or exposed mains connections. Adult guidance is recommended.

How this experiment works

Download class activity guide

Cover illustrations show component types. Functional animations explain principles and are not recorded prototype tests. Follow the supplied connection labels and pinouts.