4-Channel 5V Relay Board (optocoupled)
by Generic
SKU: PSA-CMP-RELAY-4CH
No reviews yetTypical India street price
₹150–₹320
Switch four independent loads — home-automation class sets.
Interface: 4 GPIO (often active LOW)
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Concept
Four relays with optos so MCU GND can stay quieter.
A little theory
Active LOW on most blue boards: write LOW to turn ON. Contacts are SPDT. In the classroom, treat 4-Channel 5V Relay Board (optocoupled) as a intermediate part using 4 GPIO (often active LOW). Typical India street price is about ₹150–₹320. Always verify voltage and pin labels on your exact module — silk screens vary across clones. Start with a datasheet or trusted learn guide, power the part correctly, share GND with the MCU, and test with a simple blink/read sketch before building the full project. Measure voltages with a multimeter when something fails, and keep actuator current off the MCU regulator.
How it works in a project
VCC/GND + IN1–IN4. Load on COM/NO with proper mains discipline or stay on 12 V DC.
Classroom & project use
- Pump + lamp + fan + extra
- Greenhouse
- Drivers & Relays classroom demo
Buying in India
Precautions
- Mains is lethal
- Snubbers on inductive loads
Specifications
| Channels | 4 |
| Coil | 5V |
| Category | Drivers & Relays |
| Difficulty | Intermediate |
| Voltage | 5V coil; contacts 250 VAC / 10 A rated (use far below) |
| Interface | 4 GPIO (often active LOW) |
Pinout
See module silkscreen: typically VCC, GND, and signal pins. Confirm labels against the seller photo — clones vary.
