Using relays in automated access systems lets small electronic controllers safely operate motors and solenoids that demand more current than they can supply
It’s a practical solution for hobbyists and professionals alike who wish to control powerful motors using low-output microcontrollers without risking damage
Begin your installation by evaluating your load needs and matching them to a suitable relay specification
For most door and gate applications, a mechanical relay rated for at least 10 amps at 120 or 240 volts AC is suitable, depending on the motor's power requirements
Ensure the relay’s coil operates at the same voltage as your microcontroller’s output—commonly 5V or 12V DC
Next, connect the relay to your controller
The relay will have three main terminals for the load side and two for the control side
The coil terminals should be wired to a GPIO pin and GND from your Arduino or Raspberry Pi
Always install a reverse-biased diode across the coil terminals to suppress back-EMF spikes
The high-power terminals link the AC
The relay acts as a remote switch: when triggered, it completes the motor circuit, انواع رله initiating motion
Separate the motor’s power supply from the microcontroller’s supply to minimize noise and avoid voltage drops
240V motor circuit
This isolation eliminates electromagnetic interference and protects your microcontroller from surges
Install mechanical or magnetic limit switches at both extreme endpoints of the door or gate’s travel path
Wiring the switches in series ensures immediate power cutoff upon full extension or retraction
Use delay functions or timers to hold the relay energized until the door or gate completes its motion
You can also add sensors like infrared or ultrasonic detectors to stop or reverse movement if an object is detected in the path
Use IoT platforms like Blynk, Home Assistant, or custom Node-RED flows to control the relay via smartphone or voice assistant
Always test your system with the door or gate disconnected from the motor first to confirm the relay switches correctly
Run multiple test cycles to optimize delay times and ensure limit switches respond accurately
Replace aging relays or degraded limit switches to maintain system integrity
