IoT Tank Level Monitor Kit

Classes 11-12, typical ages 16–18. Age ranges vary by learner. Guided low-voltage electronics.

Activity engagement

90–150 minutes. Explore 15–30 min · Build 30–50 min · Test and discuss 45–70 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. Wi-Fi/BLE experiments also require the local network or phone specified in the guide.

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
• ESP32S 38Pin Development Board (WIFI+BLUETOOTH) — 1 controller board
• MICRO USB DATA CABLE — 1 data cable
• HC-SR04 Ultrasonic Distance Sensor Module — 1 sensor module
• 1K Ω 1/4 Watts (10 PCS) — 1 resistor
• 1.8 kOhm 1/4 W Through-Hole Resistor — 1 resistor

What you learn

• A distance measurement can be mapped to a relative level.
• Empty and full reference distances depend on installation geometry.
• Invalid echoes must remain invalid rather than appearing full.

Connection guide

• HC-SR04 VCC → board USB 5 V output; GND → GND; TRIG → GPIO26.
• ECHO → 1 kOhm → GPIO34 node → 1.8 kOhm → GND. The divider protects the ESP32 input from the 5 V echo.

Steps to make it

1. Disconnect all power and identify the supplied part labels and pinouts before wiring.
2. Build and inspect the echo divider before connecting ECHO.
3. Point the dry sensor at a movable flat card; measure your empty and full reference distances with a ruler.
4. Enter reference distances and local Wi-Fi settings, upload and open the printed local IP.
5. Move the target between marked positions, then remove it to test the invalid-echo state.
6. Change only the named parameter for the extension, repeat the controlled trials, save observations and disconnect power afterward.

Programming resources

Arduino IDE: install esp32 by Espressif Systems 3.x; select ESP32 Dev Module for the supplied classic WROOM board. Serial Monitor: 115200 baud. GPIO is 3.3 V only.

Uses the selected board core libraries.

Download starter sketch

Test challenge

Compare browser percentage at empty, halfway and full reference positions, with five trials each.

Observation task

Target distance, valid/invalid echo, relative percentage and browser result.

Expected result

The local page shows a calibrated relative level model; it is not a direct volume or waterproof installation measurement.

If it does not work

Verify the echo divider, common ground and dry flat target. HC-SR04 modules are not waterproof; keep them away from splashes.

Try next

Add sample-age and confidence fields before considering an actual tank installation.

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.