| | Likely Cause | Solution | |-------------|------------------|---------------| | Relay does not click | No power on VCC | Check 5V and GND connections. | | Relay clicks but load doesn’t turn on | Wrong wiring (NC vs NO) | Load should be connected to COM and NO. | | Random toggling | Floating input pin | Use a pull-down (active HIGH) or pull-up (active LOW) resistor (10kΩ). | | Microcontroller resets when relay activates | Power supply insufficient | Relay coil draws ~80mA. Use a separate 5V supply for module. | | Jumper setting ignored | Poor contact | Remove/insert jumper multiple times or solder the desired connection. | 8. YL105 vs. Other Relay Modules How does the YL105 compare to similar modules?
Introduction In the world of electronics and microcontroller projects (Arduino, Raspberry Pi, ESP8266, STM32), the ability to control high-power devices—such as lamps, motors, solenoids, and pumps—using low-power logic signals is essential. The YL105 is one of the most popular and widely available single-channel relay modules designed precisely for this purpose.
Whether you are automating your home, building a robot, or designing a safety cutoff, the YL105 offers a reliable bridge between the fragile world of microcontrollers and the demanding realm of high-power electronics. Always respect the voltage ratings, adhere to proper wiring practices, and consult the SRD-05VDC-SL-C and PC817 datasheets for deeper technical insight.