Serial Relay Module

WiFi Relay ModuleKey component in the base board of the module (designed for 5V dc operation) is a cheap STC15F104 microcontroller. Next important component is a 3.3V regulator (AMS1117-3.3) chip.

Ethernet Relay Module

There’s also a small driver transistor (J3Y) to control the 5V SPDT sugar cube relay. The onboard ESP8266 WiFi module is infact a plug-in type card with an 8-pin header. The onboard 4-pin header works as an I/O header to setup/configure the WiFi Relay Module.The module can be configured with the help of any “3.3V Level USB to TTL” adapter and a suitedserial debugging software (for instance, USR-TCP232-Test-V1.3). For this, you should connect TXRX-GND pins of the USB to TTL module to RX-TX-GND pins of the 4-pin header. Recommended baud rate is 9600.

Serial Relay Module Replacement

Also remember to power up the module from an external 5V dc power source. A noteworthy fact is that the WiFi Relay module supports two modes of WiFi operation – AP and STA (actually one more mode is there – the STA + AP mode).