5V 1-Channel Low-Level Relay Module with Optocoupler Product Information
Overview
This relay module allows microcontrollers to control high-voltage devices (up to 250VAC or 30VDC, 10A) using a low-voltage signal. The optocoupler provides electrical isolation between the control circuit and the relay, enhancing safety and noise immunity.
Specifications
| Parameter | Value |
|---|---|
| Operating Voltage | 5V DC |
| Trigger Voltage | Low-level (0V to ~0.8V) |
| Trigger Current | ~5–10 mA |
| Relay Contact Ratings | 10A @ 250VAC / 10A @ 30VDC |
| Isolation Method | Optocoupler |
| Indicator LEDs | Power + Relay status |
| Control Logic | Active Low |
Pinout Description
| Pin Name | Function |
|---|---|
| VCC | 5V power supply for relay coil |
| GND | Ground reference |
| IN | Trigger input (active LOW to activate relay) |
| NO | Normally Open contact |
| COM | Common contact |
| NC | Normally Closed contact |
Wiring Instructions
Logic Side (Microcontroller)
- VCC → 5V from MCU
- GND → GND from MCU
- IN → GPIO pin (set LOW to activate relay)
Load Side (Relay Contacts)
- Connect your high-voltage device between COM and NO (for normally open behavior).
- Use COM and NC if you want the device to be ON by default.
Optocoupler Isolation Setup
Some modules include a jumper labeled JD-VCC:
- Jumper ON: Relay coil and control circuit share power (no isolation).
- Jumper OFF: Provide separate 5V to JD-VCC for relay coil, keeping control circuit isolated.
This is useful when driving the relay from noisy or high-power systems.
Example: Arduino Integration
#define RELAY_PIN 7
void setup() {
pinMode(RELAY_PIN, OUTPUT);
digitalWrite(RELAY_PIN, HIGH); // Relay OFF (active LOW logic)
}
void loop() {
digitalWrite(RELAY_PIN, LOW); // Relay ON
delay(1000);
digitalWrite(RELAY_PIN, HIGH); // Relay OFF
delay(1000);
}
Safety Tips
- Always disconnect power before wiring high-voltage loads.
- Use proper insulation and enclosures for AC wiring.
- Avoid switching inductive loads without snubber circuits to prevent relay contact damage.
Troubleshooting
| Issue | Possible Cause | Solution |
|---|---|---|
| Relay not clicking | IN pin not pulled LOW | Check GPIO logic level |
| LED on but no switching | Faulty relay or wiring | Verify load side connections |
| MCU resets on trigger | No opto-isolation or back EMF | Use separate JD-VCC + flyback diode |