Relay
4-Channel 5V Relay Module
4-channel relay board for controlling multiple appliances — ideal for home automation projects.
A 4-relay board sharing the same opto-isolated design as the single-channel version, ideal for home-automation projects controlling several devices.
Specifications
| Control side | 5V DC per channel, opto-isolated, ~15-20mA each when energized |
| Switching side | Up to 250V AC / 10A or 30V DC / 10A per channel on the common SRD-05VDC-SL-C relays used on most of these boards |
| Trigger logic | Active LOW on most modules — a LOW signal closes that channel's relay |
| Peak current | All 4 relays switching on together draw a brief combined inrush — size the 5V supply for that, don't rely on the MCU board's onboard regulator alone |
Pinout
| Pin | Name | Description |
|---|---|---|
| 1 | VCC | Power, 5V DC, control side |
| 2 | GND | Ground, control side |
| 3 | IN1-IN4 | Signal inputs, one per channel, from the MCU — active LOW on most modules |
| 4 | COM 1-4 | Common terminal, one per channel, switching side |
| 5 | NO 1-4 | Normally open, one per channel — connects to that channel's COM when energized |
| 6 | NC 1-4 | Normally closed, one per channel — connects to that channel's COM when de-energized |
Same mains-voltage isolation rules as the single-channel version, times four — keep the COM/NO/NC screw terminals physically separated from the 5V logic side of the board.