How to Wire a Relay Correctly for DIY Projects > 자유게시판

Proper relay wiring is a must-have skill for anyone building DIY circuits that bridge low-voltage control and high-voltage loads

Think of a relay as an electromagnetic gatekeeper—your low-power circuit tells it when to close the high-power circuit

Getting it right ensures safety, reliability, and prevents damage to your components

Begin by determining your relay’s configuration

Standard relays usually include five terminals: two for the coil and three for switching—COM, NO, and NC

The two coil terminals receive the activation signal, while COM, NO, and NC manage the high-power circuit

Pin configurations are not universal—consult the spec sheet or look for printed identifiers like "COIL" or "NC"

Proceed to hook up the low-voltage activation side

The coil requires a low voltage, usually 5 volts or 12 volts, depending on the relay

Link the coil’s positive lead to a GPIO pin and its negative lead to GND

Always include a flyback diode across the coil pins to protect your controller from voltage spikes when the coil turns off

Position the diode so its striped end (cathode) faces the positive terminal of the coil

Now, wire the load side

The common pin connects to your power source for the device you want to control, such as the positive terminal of a 120 volt lamp or a 12 volt motor

The normally open pin connects to the load

In its resting state, the NO contact is disconnected—current cannot pass through

Activating the coil pulls the contacts together, allowing current to flow from COM to NO

The NC terminal is typically left unconnected unless you need fail-safe operation

Verify that your external power source matches the load’s requirements and exceeds its peak draw

Do not exceed the relay’s maximum ratings

A 10A

Separate low-voltage and high-voltage traces to prevent arcing, noise, and electric shock risks

Inspect every wire and terminal before energizing the system

Always use appropriately rated, insulated cables and fasten them with terminals or wire nuts

Before connecting your appliance, verify relay operation with a multimeter or just by sound

After verifying control functionality, attach the device and رله run it under real-world load

Even low-current circuits can be dangerous—respect electricity

These electromagnetic switches are deceptively capable

They transform tiny signals into robust control actions

Unlock endless DIY potential—from automated lighting to climate control

Safety isn’t optional—it’s the foundation of every great DIY build