Mobile Charging on Coin Insertion: Working, Circuit, Functions, and Complete Guide

As mobile-phone usage continues to rise, the need for accessible and secure public charging stations has also increased. One innovative solution widely used across railway stations, bus stands, malls, hostels, and public waiting areas is the Mobile Charging on Coin Insertion System. This system allows users to charge their devices simply by inserting a coin, making it an ideal revenue-generating and utility-providing machine.

Contents

What Is a Coin-Based Mobile Charging System?

1. Power Supply Section
2. Coin Acceptor Module
3. Microcontroller Board
4. Display Unit (LCD/LED)
5. Relay Module
6. USB Charging Port
7. Timer Algorithm
1. Automatic Coin Detection
2. Timer-Based Charging
3. Intelligent Power Control
4. Universal USB Charging
5. LCD User Interface
6. Microprocessor Control
7. Overload and Short-Circuit Protection
1. Revenue Generation
2. Convenience for Users
3. Low Maintenance
4. Safety and Controlled Charging
5. Scalable and Customizable
1. How long does one coin provide charging?
2. Can this system charge all mobile phones?
3. Can the machine accept multiple coins for longer charging?
4. Is it safe to use in public areas?
5. Can I add UPI-based payment instead of coins?

In this comprehensive guide, we explore the working principle, components, circuit diagram, functional flow, advantages, and future scope of this automation system.

What Is a Coin-Based Mobile Charging System?

A coin-based mobile charging system is an electronic setup that activates a mobile charging port when a user inserts a coin into the machine. The system measures the coin’s validity, determines the charging duration, and supplies power to the charging output for a predefined time.

This technology is very useful in public places, particularly where users need urgent charging but may not be carrying a power bank.

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Block Diagram of Coin-Based Mobile Charging System

Below is a simplified conceptual diagram:

     +-------------------------+
     |      Power Supply       |
     +-----------+-------------+
                 |
                 v
     +-------------------------+
     |      Coin Acceptor      |
     +-----------+-------------+
                 |
                 v
     +-------------------------+
     |  Microcontroller Unit   |
     | (ATmega/Arduino/PIC)    |
     +-----------+-------------+
                 |
     +-----------+------------+
     |                        |
     v                        v
 Timer/Control Unit       LCD Display
     |                        |
     v                        |
 Relay/Output Driver <--------+
     |
     v
+-----------+
| USB Port  |
| Charger   |
+-----------+

Working Principle of the Mobile Charging on Coin Insertion Project

The device works on a simple sequence:

User inserts a coin
The coin acceptor detects size, weight, or metal composition.
Signal sent to microcontroller
Coin acceptor sends a digital pulse.
Microcontroller verifies and triggers timer
If the coin is valid, the timer starts based on pre-programmed settings.
Relay switches ON the USB charging port
Charging becomes active for the set duration (e.g., 30 minutes per coin).
Time expires, system stops output
The relay turns OFF, halting power flow.
System resets and waits for next user.

Circuit Description of Coin-Operated Mobile Charging System

A typical circuit includes:

1. Power Supply Section

Step-down transformer or SMPS
Bridge rectifier
Filter capacitor
5V/12V voltage regulator

2. Coin Acceptor Module

Mechanical or electronic
Sends pulse output to microcontroller

3. Microcontroller Board

Common MCU options:

Arduino UNO (Atmega328)
PIC16F877A
ATmega16/32
NodeMCU if IoT features are added

4. Display Unit (LCD/LED)

Used to show:

“Insert Coin”
Charging time remaining
Charging completed message

5. Relay Module

Acts as an electronic switch to turn charging port ON/OFF.

6. USB Charging Port

5V output to charge mobile phones.

7. Timer Algorithm

Controls relay based on the coin value.

Functional Flow Diagram

    +---------------------------+
    |     Start / Standby       |
    +-------------+-------------+
                  |
                  v
     +---------------------------+
     |   Display "Insert Coin"   |
     +-------------+-------------+
                  |
                  v
     +---------------------------+
     |   Coin Inserted? (Y/N)    |
     +-----+---------------+-----+
           |               |
           v               v
         YES               NO
           |           Wait/Loop
           v
     +---------------------------+
     | Validate Coin and Pulse   |
     +-------------+-------------+
                  |
                  v
     +---------------------------+
     | Set Charging Timer (e.g., |
     |       30 Minutes)         |
     +-------------+-------------+
                  |
                  v
     +---------------------------+
     | Activate Relay / USB Port |
     +-------------+-------------+
                  |
                  v
     +---------------------------+
     | Count Down Timer Display  |
     +-------------+-------------+
                  |
                  v
     +---------------------------+
     | Timer Over → Turn OFF     |
     +-------------+-------------+
                  |
                  v
     +---------------------------+
     | Reset for Next Operation  |
    +---------------------------+

Features and Functions of the Coin-Based Charging System

1. Automatic Coin Detection

Identifies whether the inserted coin is valid.

2. Timer-Based Charging

Charging duration depends on:

Coin value
Pre-programmed settings

3. Intelligent Power Control

Relay ensures safe switching and prevents overcurrent.

4. Universal USB Charging

Supports any smartphone:

Android
iPhone (with user cable)
Tablets
USB gadgets

5. LCD User Interface

Displays:

Remaining time
Charging status
Instructions

6. Microprocessor Control

Ensures:

Accuracy
Safety
Repeatability

7. Overload and Short-Circuit Protection

Safe for public environments.

Advantages of Mobile Charging on Coin Insertion

1. Revenue Generation

A perfect micro-business setup for:

Railway stations
Bus stands
Parks
Shopping malls

2. Convenience for Users

Provides emergency charging when:

Battery dies
Users forget power banks
No charging points are available

3. Low Maintenance

Once installed, it operates automatically.

4. Safety and Controlled Charging

Prevents misuse of power.

5. Scalable and Customizable

You can add:

Multiple charging ports
IoT monitoring
Digital payment integration (UPI, QR code)

Applications of Coin-Operated Mobile Charging Machines

Public transport stations
Airports and terminals
College campuses
Hostels
Shopping malls
Hospitals
Waiting rooms
Cyber cafés
Parks and recreation areas

Future Scope and Upgrades

IoT-Based Monitoring
- Track revenue in real time
- Get device health alerts
UPI Payment or Token System
Users pay digitally instead of coins.
Solar-Powered Charging Station
Zero electricity cost.
Smartphone Lockers with Charging
Secure charging compartments.
Multiple USB Fast-Charging Ports
Add QC 3.0 or PD-Type-C support.
LED Advertising Display
Additional revenue stream.

Sample Technical Specifications

Component	Specification
Power Input	230V AC / 12V DC
Output	5V USB, 1A–2.1A
Controller	ATmega/PIC/Arduino
Charging Duration	15–60 minutes per coin
Coin Type	₹1, ₹5, tokens
Safety Features	Fuse, overload cut-off, surge protection

Why This System Is Perfect for Public Use

The coin-operated charging station provides a controlled environment where users get measured and secure charging time without overloading the electrical system. Its modular design makes it ideal for vendors, shop owners, and institutions looking to create low-cost, reliable solutions for public charging needs.

Simple ASCII Internal Wiring Diagram

 AC 230V
    |
[Power Supply]---12V---->[Voltage Regulator 5V]----> MCU
                               |
                               +--> LCD
                               |
Coin Acceptor ---> Pulse ----> MCU ----> Relay ----> USB Charger Port

Conclusion

A Mobile Charging on Coin Insertion System is a practical, cost-effective, and user-friendly solution for public charging needs. This system not only provides convenience to users but can also generate additional revenue for businesses and public service providers. With easy scalability and options for integrating IoT, digital payments, and fast charging, this solution is an excellent example of functional electronics automation.

Whether you’re a student working on a final-year engineering project or an entrepreneur planning to install public charging stations, this comprehensive guide provides everything you need to understand and build a coin-based mobile charging setup.

FAQs

1. How long does one coin provide charging?

Typically 15–30 minutes, depending on configuration.

2. Can this system charge all mobile phones?

Yes, any phone that supports USB charging.

3. Can the machine accept multiple coins for longer charging?

Yes, the microcontroller can be programmed accordingly.

4. Is it safe to use in public areas?

Yes, it includes protection against overload and short circuits.

5. Can I add UPI-based payment instead of coins?

Yes, using IoT or NFC modules.