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ESP32

₹500 – ₹1,500

3 – 6 Hours

Partial Kit

Set Up a Smart Notifier System: Transform Your Home with BLE

Transform your home into a smart space by building a Bluetooth Low Energy (BLE) notifier that detects a specific smartwatch or smartphone MAC address as it enters range.

Originally published on ElectronicsForU

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

10pcs - 220 ohm 1/4 W Resistor Set Rs. 39.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

This list includes a generic resistor set as a placeholder — it is not matched to the exact value or part number this circuit needs. The correct one is specified on the original source page linked above; check it before buying.

We don't carry yet: 9V Battery + Snap
Speaker / Audio Amplifier
Smartwatch

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How It Works

The Smart Notifier System operates by combining wireless microcontroller scanning with a classic transistor-driven audio circuit. At the heart of the system is the ESP32 DevKit v1, which continuously scans its surrounding environment for Bluetooth Low Energy (BLE) advertisements. When the ESP32 detects the specific target MAC address belonging to a nearby smartwatch, its firmware identifies that the device has entered the defined proximity range. Upon establishing this presence detection event, the microcontroller outputs a digital control signal from one of its GPIO pins. This signal is routed through a 1kΩ current-limiting resistor (R1) to the base terminal of a BC547 NPN bipolar junction transistor (IC2). Acting as an electronic switch, the BC547 modulates current flow from the 9V battery power source through the BT66 integrated circuit (IC1). The BT66 is a specialized melody generator IC that, when powered, produces an analog audio signal. This audio signal drives a small speaker connected to the output stage, translating the electrical waveform into an audible alert tone. By integrating modern wireless proximity tracking with discrete analog audio amplification and generation components, the system successfully bridges digital IoT logic with traditional hardware notification methods.

Why Build This

Design and deploy automated residential presence-detection systems using Bluetooth Low Energy MAC address filtering.

Interface low-voltage microcontroller digital outputs with discrete transistor-switched analog audio circuits powered by higher-voltage supplies.

Implement real-world smart home automation triggers capable of responding dynamically to the physical movement of personal wearable devices.

Real-World Application

Home automation, automated security gate alerts, personalized welcoming systems, and presence detection for residential or office environments.

Skills You'll Learn

Bluetooth Low Energy device scanning

microcontroller GPIO control

transistor switching circuits

analog audio generation

system power budgeting

Safety Precautions

Ensure proper wiring and voltage matching when connecting the 9V battery and audio components to avoid short circuits.

Technology Tags

BLUETOOTH LOW ENERGY (BLE)

ESP32

SMART HOME

WIRELESS COMMUNICATION

IOT

MAC ADDRESS SCANNING

Frequently Asked Questions

How does the ESP32 know which smartwatch to look for?

The ESP32 firmware is programmed to scan for a specific, hardcoded Bluetooth Low Energy (BLE) MAC address unique to your smartwatch.

What is the purpose of the BC547 transistor in this circuit?

The BC547 acts as an electronic switch, allowing the low-voltage digital signal from the ESP32 to control the higher-voltage audio generation circuit powered by the 9V battery.

Can I use a different power supply instead of a 9V battery?

You must ensure that your power supply matches the voltage requirements of both the ESP32 and the audio components to prevent logic level mismatches or component damage.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

PRJ-00993