USB serial port control relay is an upgraded and advanced version featuring a optocoupler protection circuit to prevent interference and enable speed transmission. Key benefits Reliable switching with USB serial control: easy to integrate with standard USB serial interfaces for controlling the load via software or microcontrollers. Electrical isolation and protection: optocoupler protection isolates the control side from the load, reducing interference and protecting sensitive circuitry. Fast and stable performance: designed for speed transmission and quick switching responses. Safe load switching: the relay output acts as a switching contact with no voltage supplied by the module to the load, enhancing safety and versatility. Built in protection: overcurrent protection helps prevent damage to the module and connected circuitry. Simple operation with clear contact behavior: COM is connected to NC when not energized, and to NO when energized. What it is A USB serial port controlled relay module with a single channel. The relay provides common (COM), normally closed (NC), and normally open (NO) contacts for flexible wiring. How it works When the relay coil is not energized, COM is connected to NC. When voltage is applied to energize the coil, COM switches to NO. The load side receives no power from the module; the load must be supplied externally through the appropriate power source. Output and protection The relay output terminals function as a dry electronic switch. They do not supply voltage to the load; the control side and load side are electrically isolated. The module includes overcurrent protection to safeguard the circuit. Design and compatibility Designed for USB serial port control with a compact form factor suitable for integration into projects and enclosures. Intended for use in systems requiring reliable relay switching with strong protection against interference and fast response times. Use scenarios Home automation: control lighting, fans, or other appliances via PC software or a microcontroller over USB serial, with safe isolation and quick switching. Test bench or lab automation: programmatically switch power to instruments or devices during experiments, while protecting control electronics from load transients. DIY and smallscale automation: integrate into projects that require a simple on/off control of devices, using separate power for the load and a reliable switching interface. Note The module provides only the switching contacts; ensure the load has its own appropriate power supply and that wiring follows safety standards.