Project Hub /Security Surveillance & Defense/Smart Door Lock (Keypad/App/OTP)/DIY OTP based Locker to Open Door Lock Wirelessly

Intermediate

ESP32

₹1,500 – ₹5,000

3 – 6 Hours

Partial Kit

DIY OTP based Locker to Open Door Lock Wirelessly

Build a wireless, OTP-controlled smart door lock system using an ESP32 board and Telegram to securely generate and share temporary access codes.

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.

ESP32 WiFi+Bluetooth CP2102 Development Board Rs. 520.00
5V 1 Channel Relay Module Rs. 45.00
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

We don't carry yet: Other Dev Board (Indusboard / Maixduino / misc)
Solenoid / Electric Lock

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How It Works

The DIY OTP-based wireless door lock system operates by connecting an ESP32 microcontroller to a local Wi-Fi network, allowing it to interface with the internet. Using the AsyncTelegram2 library inside the Arduino IDE, the ESP32 communicates with the Telegram bot API to receive commands and send messages. When a user requests access, a One-Time Password (OTP) is generated and verified through the system. Upon entering or validating the correct OTP, the microcontroller changes the digital output state of its GPIO pin, which is connected to a 5V SPST relay module. The relay acts as an electrically operated switch that isolates the low-power ESP32 logic circuit from the higher-current 5V solenoid lock. When triggered, the relay closes its contacts, supplying power to actuate the solenoid lock and physically open the door or locker. Jumper wires are used to establish all necessary power, ground, and signal connections between the IndusBoard/ESP32, the relay module, and the power supply.

Why Build This

Design and implement a modern smart home access control system utilizing cloud-based messaging platforms like Telegram.

Gain practical engineering experience in integrating microcontrollers with electromechanical actuators and switching relays.

Develop secure temporary access protocols suitable for parcel drop boxes, guest management, and secure room automation.

Real-World Application

Smart home access control, parcel delivery drop boxes, secure room locking, and guest access management.

Skills You'll Learn

Microcontroller Wi-Fi integration

API communication via Telegram

Relay interfacing with inductive loads

Digital I/O control

OTP logic implementation

Safety Precautions

Exercise caution when working with 5V relay modules and inductive loads like solenoid locks to prevent back-EMF or power supply instability.

Technology Tags

ESP32

INDUSBOARD

TELEGRAM API

CHATBOT

SOLENOID LOCK

RELAY MODULE

WI-FI

IOT

ARDUINO IDE

Frequently Asked Questions

Why is a relay module required between the ESP32 and the solenoid lock?

The ESP32 digital pins operate at 3.3V and cannot supply enough current to drive a 5V solenoid lock directly. The relay module acts as an isolated switch, allowing the low-power microcontroller to safely control the higher-power lock circuit.

Can this system function without an active internet connection?

No, the system relies on the ESP32 connecting to Wi-Fi to communicate with the Telegram bot API for receiving and validating the OTP codes remotely.

What power supply considerations should I keep in mind for the solenoid lock?

Solenoid locks are inductive loads that draw a significant surge current when activated, so your 5V power supply must be capable of handling this transient load without causing voltage sips that could reset the ESP32.

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.

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