ESP-01S Relay Module WiFi Smart Switch ESP8266 Remote Control Smart Home Compatible

ESP-01S Relay Module Product Overview

The ESP-01S relay module is a WiFi smart switch based on the ESP8266 chip, featuring an onboard SONGLE SRD-05VDC-SL-C relay with 5V power supply and 10A 250VAC load capacity. Users can remotely control home appliances, lights, water pumps, and other devices via mobile App, web interface, or smart speakers. The module is available in three configurations: board only (without ESP-01), board with pre-soldered ESP-01, or ESP-01 module alone. Ideal for smart sockets, smart light control, and IoT DIY projects.

ESP-01S Relay Module Core Features

ESP-01S WiFi Module： Based on ESP8266 chip, supports 802.11 b/g/n wireless protocol for remote control via mobile App

Onboard SONGLE Relay： SONGLE SRD-05VDC-SL-C relay with 10A 250VAC / 10A 30VDC contact rating

5V Power Supply： Micro-USB power input, compatible with phone chargers, USB adapters, or 5V from development boards

High/Low Level Trigger Selectable： Onboard jumper or solder pad for high or low level trigger input

Optocoupler Isolation： Optically isolated input and output to protect control side circuitry

Status Indicators： Power LED and relay activation LED for clear status display

Three Configurations： Board only (no ESP-01), board with ESP-01, or ESP-01 module alone

Terminal Block Output： Clearly marked COM, NO, NC terminals for easy wiring

ESP-01S Relay Module Applications

Smart socket WiFi switch, mobile remote control for home appliances, DIY smart lighting, voice control with smart speakers, automatic garden irrigation, aquarium automation, industrial equipment remote control

ESP-01S Relay Module Key Advantages

Plug-in ESP-01S Design： Separate relay board and ESP-01S module for easy replacement and firmware flashing

Multiple Configurations Available： Choose from board only, board with ESP-01, or ESP-01 module based on your needs

10A High Load Capacity： Directly controls resistive loads up to 2500W, suitable for most home appliances

Optocoupler Isolation for Safety： Electrical isolation between control and load sides protects ESP module

Smart Speaker Compatibility： Works with Tmall Genie, Xiao Ai, Google Home, and other smart speakers for voice control

Rich Open-Source Firmware Support： Compatible with ESPHome, Tasmota, Blinker, and other mainstream IoT firmware

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FAQ:

1. What is the ESP‑01S Relay Module and its key specifications?
   This is a WiFi smart switch that combines an ESP8266 ESP‑01S module with a 5 V relay on a single compact board. The relay is driven by the ESP‑01S’s GPIO2 pin and can switch up to 10 A at 250 V AC or 10 A at 30 V DC. The board typically includes a 3.3 V regulator to power the ESP‑01S from the 5 V DC input, and it exposes the UART (TX/RX) pins for programming. The module is widely used for remote control of lights, appliances, garage doors, and other DIY home automation projects.

2. How do I connect the ESP‑01S Relay Module and what are the pinouts?
   The board has a 4‑pin input header: VCC (5 V), GND, RX, and TX. Connect a 5 V DC supply to VCC and GND; the on‑board regulator provides 3.3 V to the ESP‑01S. The relay output is accessible through a 3‑terminal screw block: NO (normally open), COM (common), and NC (normally closed). The relay is controlled by GPIO2 — when GPIO2 goes HIGH, the relay energises, connecting COM to NO. The UART pins are used only for programming; for normal operation, the module can run standalone once configured.

3. How do I program the ESP‑01S Relay Module with Tasmota, ESPHome, or Arduino?
   You need a USB‑to‑serial adapter (3.3 V) or a dedicated ESP‑01 programmer. Connect VCC (3.3 V), GND, TX‑to‑RX, RX‑to‑TX between the adapter and the module. To enter flash mode, pull GPIO0 LOW while powering up. Then use Tasmota Web Installer, ESPHome Flasher, or Arduino IDE (with the ESP8266 board package) to upload firmware. Once flashed, remove the GPIO0 jumper and reboot. The relay can be controlled via MQTT, HTTP, or a local web interface depending on the chosen firmware.

4. How can I control the relay remotely via WiFi, MQTT, or HTTP?
   After installing firmware like Tasmota, the module connects to your WiFi network. You can then toggle the relay with a simple HTTP GET request (e.g., http:///cm?cmnd=Power%20TOGGLE) or via MQTT by publishing a message to the device's command topic. The relay status is reported back, allowing you to build web dashboards, smartphone apps, or integrate with automation platforms. No cloud account is required; everything runs locally on your network.

5. Can this module integrate with Home Assistant, Alexa, or Google Home?
   Yes, it integrates seamlessly. With Tasmota or ESPHome, the module can be auto‑discovered by Home Assistant through MQTT or the native API. Using emulated Hue or MQTT‑based plugins, you can also control it with Amazon Alexa and Google Assistant via a local server. ESPHome offers direct Home Assistant integration without MQTT. This turns a $5 relay into a fully voice‑controlled smart switch.

6. What is the maximum voltage and current the relay can switch?
   The relay is rated for 10 A at 250 V AC and 10 A at 30 V DC. It can safely control most household lights, fans, small motors, and resistive loads. For inductive loads (motors, transformers), de‑rate the current or add a snubber circuit to protect the relay contacts. The relay contacts are galvanically isolated from the low‑voltage side, providing > 1.5 kV isolation.

7. What power supply does the module need, and how is the ESP‑01S powered?
   The board requires a 5 V DC power supply (≥ 500 mA recommended). The on‑board AMS1117‑3.3 regulator steps this down to 3.3 V for the ESP‑01S. The relay coil draws about 70 mA when active, and the ESP‑01S peaks around 300 mA during WiFi transmission. A stable 5 V supply is essential; a USB charger or a simple phone adapter works well.

8. How do I put the ESP‑01S into flash mode to upload firmware?
   To enter flash mode, you must pull GPIO0 (IO0) to GND while the module is powered on. On the relay board, this is usually done by bridging a solder jumper or connecting a wire between the GPIO0 pin and GND. After the firmware upload is complete, remove the GPIO0‑GND connection and power‑cycle the board. The relay board is designed so that GPIO2 and GPIO0 are pulled high by default, ensuring normal boot when not in programming mode.

9. Are there any safety precautions when using this relay module?
   Yes — the relay terminals carry mains voltage, which can be lethal. Always disconnect power before wiring, use insulated screwdrivers, and mount the board inside a protective enclosure. Do not touch the relay terminals while the circuit is live. The module is not certified for use as a safety device; do not rely on it for life‑critical applications. Ensure the load does not exceed the relay rating, and provide a fuse or circuit breaker in series with the load for over‑current protection.

10. What are the most typical applications of the ESP‑01S Relay Module?
    It is widely used in home automation to control lights, fans, coffee makers, and water heaters remotely. Other common uses include garage door openers, smart garden watering, 3D printer power control, aquarium light timers, and DIY access control. Its small size, low cost, and easy integration with open‑source firmware make it a favourite for both beginners and experienced IoT makers.