ESP8266 ESP-01S 5V WiFi Relay Module Smart Switch
Share :
The ESP8266 ESP-01S 5V WiFi Relay Module is a single, compact board that integrates the popular ESP-01S Wi-Fi microcontroller with a single 5V relay, making it a simple solution for controlling electrical devices wirelessly in IoT and home automation projects.
| Feature | Detail |
| Microcontroller | ESP-01S (based on ESP8266 chip) |
| Operating Voltage | 5V DC (The module has an onboard regulator to supply 3.3V to the ESP-01S) |
| Relay Coil Voltage | 5V DC |
| Relay Load Capacity | 10A at 250V AC or 10A at 30V DC |
| Control Pin | GPIO0 on the ESP-01S |
| Trigger Logic | Active LOW (Pulling GPIO0 right arrow LOW typically activates the relay) |
| Isolation | Often includes an optocoupler for electrical isolation between the Wi-Fi control circuit and the relay. |
The module is designed for simplicity, serving as a self-contained Wi-Fi switch once programmed.
Power: The entire module is powered by a single 5V DC supply connected to its VCC and GND pins.
Programming: The ESP-01S is usually programmed using a separate USB-to-Serial (FTDI) adapter. Since the ESP-01S does not have an onboard USB port, it must be removed from the relay board and placed into a programming adapter where GPIO0 is temporarily connected to GND to enter flash mode. Once programmed, it is plugged back into the relay module's header.
Control and Load Wiring
The ESP-01S uses its GPIO0 pin to control the relay's switching transistor.
| Relay Terminal | Function | Connection |
| COM | Common | Connects to one side of the AC or DC power source (the source wire). |
| NO | Normally Open | Connects to the device's wire (e.g., the light bulb's wire). The circuit is OFF by default. |
| NC | Normally Closed | Connects to the device's wire. The circuit is ON by default. |
To switch a light bulb, you typically wire the COM and NO terminals. Sending the LOW signal from the ESP-01S closes the circuit (turns the light ON), and sending a HIGH signal opens it (turns the light OFF).
This module is a popular choice because it integrates everything into one small PCB, allowing you to create a remote-controlled smart switch with minimal external wiring.
To see an example of how this module is used in a home automation setup, check out this video: How to Program the ESP8266 ESP01 Wi-Fi Relay Module | RemoteXY | FLProg.