4-Channel 5V Relay Module, Optocoupler Isolated

This 4-channel relay module scales the familiar single-relay opto-isolated switching setup up to four independent channels on one board, letting a single microcontroller control four separate mains-voltage or higher-current DC loads from four GPIO pins, rather than needing four separate single-relay boards wired individually across a project.

Each of the four channels is electrically isolated through its own optocoupler, protecting the microcontroller side of the circuit from voltage spikes or electrical noise generated on the switched-load side - a safety and reliability measure that matters more as the number of controlled loads increases, since any single channel's load-side noise staying contained to that channel only is a genuinely valuable design property. Every channel switches independently of the others, so one relay can be active while the rest sit idle, giving full independent control rather than an all-or-nothing group switch.

Switching capacity per channel is rated at 240VAC/10A or 30VDC/10A, matching the single-channel version's rating but now available across four separate circuits from one board. Trigger voltage is 5VDC with roughly 15-20mA trigger current per channel, directly compatible with standard 5V-logic microcontroller GPIO output. Compatibility is documented across a wide range of platforms - Arduino, 8051, AVR, PIC, DSP, ARM, MSP430 - reflecting how broadly this relay module format gets used.

Four individual LED indicators give at-a-glance confirmation of which channels are currently active, useful for debugging multi-relay control logic without needing to probe each relay individually. Builders automating multiple independent loads - a home automation system controlling several lights or appliances, an irrigation controller switching multiple valves, or any multi-zone control project - will find this 4-channel relay module a practical way to scale up control without stacking multiple single-relay boards.