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.
At its core, this project bridges the gap between low-voltage digital microcontrollers and high-voltage electrical loads by utilizing an electromechanical one-channel relay module. An Arduino Uno operates on low-voltage direct current (typically 5V logic), which is insufficient for directly driving standard AC appliances. To solve this, the Arduino sends a digital control signal via a jumper wire to the relay module's input pin. Inside the module, this low-power control signal triggers an onboard transistor, which in turn energizes an electromagnetic coil. When the coil is energized, it creates a magnetic field that physically pulls a mechanical switch (the armature) from one contact to another. This switching action acts as an electrically isolated barrier: the low-voltage DC side remains completely separated from the high-voltage AC side. By breaking or completing the circuit on the high-voltage side, the relay allows the Arduino to safely control the flow of mains electricity to an AC-powered lamp or appliance.
Why Build This
Develop foundational systems integration skills required for undergraduate engineering home automation and smart switch prototypes.
Gain practical hardware experience in safely isolating low-voltage digital logic from high-voltage mains power circuits.
Implement programmatic control over heavy-duty physical loads and industrial machinery components using microcontrollers.
Real-World Application
Home automation, appliance control, smart switches, and industrial machinery control.
Skills You'll Learn
relay logic
galvanic isolation
microcontroller digital output control
high-voltage circuit safety
electromagnetic actuation
Safety Precautions
This project involves working with HIGH AC voltage (mains electricity). Improper handling can lead to serious injury or death. Ensure the lamp is unplugged and the power source is switched off before making any wiring connections.
Technology Tags
ARDUINO
RELAY
AC MAINS
ELECTRONICS
HARDWARE
RELAYS
SWITCHES
Frequently Asked Questions
Arduino pins operate at 5V DC and can only supply a few milliamps of current, whereas AC lamps run on high voltages (like 120V or 230V AC) and require substantial current. Direct connection would instantly destroy the microcontroller and pose a severe shock hazard.
The relay module acts as an electrically isolated switch. It uses a low-power electromagnet controlled by the Arduino's 5V signal to physically open or close the high-voltage AC circuit without letting the high voltage reach the microcontroller.
Yes, as long as the electrical current and voltage requirements of the appliance do not exceed the maximum ratings specified on the relay module's built-in switch contacts.
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.
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
