Reliable RTC Relay Timer Circuit with Arduino Nano for Scheduled Appliance Control Every 7 Steps

The RTC Relay Timer Circuit with Arduino Nano for Scheduled Appliance Control is an excellent project for automating appliances. This guide explains how to make an RTC Relay Timer Circuit with Arduino Nano for Scheduled Appliance Control with minimal components. Learn the step-by-step process of wiring and programming an RTC Relay Timer Circuit with Arduino Nano for Scheduled Appliance Control using a DS1307 RTC module.

We’ll cover how the RTC Relay Timer Circuit with Arduino Nano for Scheduled Appliance Control works, how to set ON/OFF times, and how to test your setup. The RTC Relay Timer Circuit with Arduino Nano for Scheduled Appliance Control ensures precise switching even after a power cut. By following this tutorial, you can easily build an RTC Relay Timer Circuit with Arduino Nano for Scheduled Appliance Control for home or industrial automation.

Introduction

As someone who’s been designing electronics for over a decade, I can tell you that precise time-based control is a game changer in automation. Whether you want to switch lights, fans, pumps, or chargers, relying on manual operation is both inefficient and unreliable. That’s where an RTC Relay Timer Circuit with Arduino Nano for Scheduled Appliance Control comes in.

Unlike simple delay timers, this design uses a DS307 Real Time Clock (RTC) module that keeps time even when power is disconnected, thanks to its onboard battery backup. That means you can program an appliance to turn ON or OFF at a specific time every day—without resetting the system after a power cut.

In this guide, I’ll take you through every 7 Steps—from the circuit diagram to testing—so you can replicate this project confidently.

 Materials for the Project (RTC Relay Timer Circuit)

Circuit Diagram Explanation

Here’s how the RTC Relay Timer Circuit with Arduino Nano for Scheduled Appliance Control works:

• The Arduino Nano communicates with the DS1307 RTC module over the I²C interface (SDA to A4, SCL to A5).

• The RTC sends accurate time data to the Arduino.

• When the Arduino’s internal logic detects that the current time matches the preset ON time, it sends a HIGH signal to the BC547 transistor.

• This activates the 5V relay, which switches the connected appliance ON.

• The 1N4148 diode protects against voltage spikes generated by the relay coil when turning off.

• Push buttons allow time setting adjustments without needing to re-upload the Arduino sketch.

• The 10K trimpot can be used to adjust parameters or LCD contrast if you integrate a display.

⚠ Safety Note: If you’re switching AC mains loads, always ensure proper insulation and follow electrical safety standards.

Download Circuit Diagram

Gerber Files

Step-by-Step Guide

Step 1 – Understanding the RTC Module

The DS1307 module provides real-time tracking of hours, minutes, seconds, day, date, month, and year. With its temperature-compensated crystal oscillator, it maintains time accuracy to within ±2 ppm, or about one minute per year.

Step 2 – Wiring the Circuit

1. First connect Arduino.

2. After that, connect a 2-pin terminal block and connect its 1 pin to the 5V pins of the Arduino and its other pin to ground.

3. After that, connect the RTC module and connect its VCC pin to the 5-volt pin of the Arduino, its ground pin to ground, its SDA pin to the A4 pin of the Arduino, and its SCL pin to the A5 pin of the Arduino.

4. After that, connect a 16 by 2 LCD and connect its pin numbers 1, 5, 7, 8, 9, 10, and 16 to ground and its pin numbers 2 and 15 to 5V pins of the Arduino, and its pin number 4 to pin D6 of the Arduino. It’s pin number 6 to pin D7 of Arduino. It’s pin number 11 to pin the 8 of Arduino. It’s pin number 12 to pin D9 of the Arduino. It’s pin number 13 to pin D10 of the Arduino. It’s pin number 14 to pin 11 of the Arduino.

5. After that, connect the 10k trim port and connect its one side pin to fivefold. its center pin to pin number three of the LCD and its other side pin to ground.

6. After that, connect the push button and connect one of its pins to pin D2 of the Arduino and its other pin to ground.

7. After that, connect another push button and connect its one pin to pin D3 of the Arduino and its other pin to ground.

8. After that, connect another push button and connect its one pin to pin D4 of the Arduino and its other pin to ground.

9. After that, connect a BC547 transistor and connect its pin number three to ground.

10. After that, connect a 1k resistor and connect one of its pins to pin D5 of the Arduino and its other pin to pin number two of the transistor. After that, connect a five-volt relay and connect its one coil pin to the five full pins of the Arduino and its other coil pin to pin number one of the transistor.

11. After that, connect a 1N4148 diode and connect its anode to pin number 1 of the transistor and its cathode to 5 full pins of the Arduino; after that, connect a 2-pin terminal block and connect its one pin to the normally open pin of the relay and its other pin to the common pin of the relay, so we have completed all the connections.

Step 3 – Installing: Now let’s upload the code to Arduino.

Arduino Code

Step 5 – Testing the ON/OFF Function

Upload the sketch and use the serial monitor to check time readings. Adjust ON/OFF times for quick testing.

Step 6 – Adding User Interface (Optional)

• Use one button to set hours

• Another for minutes

• Third button to toggle ON/OFF schedule setting mode

• Add a 16×2 I²C LCD to display the time and relay status.

Step 7 – Enclosure and Deployment

• Place the relay and high-voltage wiring in an insulated enclosure

• Mount the Arduino and RTC securely

• Keep low-voltage and high-voltage sections physically separated

Applications

• Automated lighting systems

• Scheduled irrigation pumps

• Timed battery charging systems

• Industrial process control

• Security systems with timed activation

FAQs

Q1: Can I use a DS1307 instead of a DS1307?
A: Yes, but DS1307 is much more accurate.

Q2: What happens if power is lost?
A: The DS1307 has a battery backup, so timekeeping continues.

Q3: Can I control multiple devices?
A: Yes, by adding more relays and modifying the code.

Q4: Will it work for both AC and DC loads?
A: Yes, as long as the relay is rated for the voltage and current.

Q5: Can I make it portable?
A: Yes, by powering the circuit with a DC adapter or battery pack.