Project Hub /Basic Analog & Power Electronics/DIY Automatic Water Vending Machine using Arduino

Intermediate

ARDUINO

₹1,500 – ₹5,000

3 – 6 Hours

Partial Kit

DIY Automatic Water Vending Machine using Arduino

Build a portable drinking water vending machine using an Arduino, a coin acceptor module, and a TRIAC-controlled AC water pump.

Originally published on CircuitDigest

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.

Arduino UNO R3 Board (Compatible) – ATmega328P Microcontroller with USB Cable Rs. 999.00
MAX7219-4 Dot Matrix LED Display Module – 4-in-1 Cascaded Panel Rs. 698.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
10pcs 5mm RED Diffused Light Emitting Diodes - LEDs Set Rs. 39.00
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: Solid State Relay / Triac / Dimmer
Water Pump / Valve
Pipes / Tubing / Hose / Fittings
Coin Acceptor Module

Browse all components

How It Works

The DIY Automatic Water Vending Machine operates through an integrated system of coin detection, microcontroller processing, and high-voltage power control. At the core of the setup is an Arduino UNO (or Arduino Mega 2560), which continuously monitors the signal pins connected to the Coin Acceptor Module. When a user inserts a valid coin, the coin acceptor generates a series of digital pulses corresponding to the coin's denomination. The Arduino counts these pulses to verify that the correct payment amount has been reached. Once payment is confirmed, the microcontroller triggers an output pin connected to an MOC3021 Optocoupler. This optocoupler provides essential electrical isolation between the low-voltage DC control side and the high-voltage AC load side. Upon receiving the signal from the Arduino, the internal phototriac in the MOC3021 conducts, which in turn fires the gate of the BT136 TRIAC. The TRIAC acts as a solid-state switch that allows 230V AC mains electricity to flow directly to the 230V AC Water Pump. Water is then drawn through the connected pipes and fittings for a predetermined duration programmed via the Arduino IDE before the microcontroller cuts the signal, turning off the TRIAC and stopping the pump.

Why Build This

Design and prototype a functional commercial-style automated water kiosk system suitable for public beverage dispensing.

Gain practical undergraduate-level experience integrating low-voltage microcontroller logic with high-voltage AC peripheral hardware.

Implement reliable coin-based automated transactional control systems for fluid-dispensing engineering applications.

Real-World Application

Public beverage dispensing, automated water kiosks, and commercial vending systems.

Skills You'll Learn

Coin acceptor pulse counting

Optically isolated TRIAC switching

AC mains load control

Microcontroller digital input processing

Relay-less high-voltage actuation

Fluid dispensing automation

Safety Precautions

Exercise extreme caution when working with 230V AC mains voltage connected to the TRIAC and water pump circuitry.

Technology Tags

ARDUINO

COIN ACCEPTOR

TRIAC

OPTOCOUPLER

AC WATER PUMP

HARDWARE INTERRUPTS

AUTOMATION

Frequently Asked Questions

Can I power the 230V AC water pump directly from the Arduino digital output pins?

No, absolutely not. Arduino pins operate at 5V DC and can only supply a few milliamps, which is entirely insufficient for an AC pump and poses a severe shock hazard. You must use the MOC3021 optocoupler and BT136 TRIAC circuit to safely switch the 230V AC mains power.

How does the Arduino know how many coins have been inserted?

The Coin Acceptor Module is programmed to output specific electrical pulses every time a recognized coin passes through it. The Arduino reads these incoming pulses using digital input pins and counts them to track the total inserted credit.

Why is an optocoupler required between the Arduino and the TRIAC?

The optocoupler provides galvanic isolation, meaning it uses light to transmit signals across a barrier without any direct electrical connection. This protects your sensitive Arduino and your computer from dangerous high-voltage feedback originating from the 230V AC mains circuit.

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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