12V DC power supply relay module is a commonly used electronic module. It operates on 12V DC power and can control the switching of a high-current circuit with a small current signal. Here is a detailed introduction:

Basic Components

Power Input: Connects to a 12V DC power supply to provide the module with operating energy.

Control Signal Input: Receives external logic signals, such as signals from a microcontroller, to trigger the relay.

Transistor Switching Circuit: Typically composed of an NPN transistor, it controls the switching of power to the relay coil by controlling the base current.

Freewheeling Diode: Connected in parallel with the relay coil, it releases the back electromotive force generated by the coil when the relay is de-energized, protecting other components in the circuit.

LED Indicator: Used to indicate the relay's operating status; the LED is usually lit when the relay is energized and off when it is de-energized.

Working Principle

When a control signal is input, turning on the transistor switching circuit, the 12V power supply powers the relay coil through the transistor. The coil generates a magnetic field, attracting the armature, causing the normally open contacts of the relay to close and the normally closed contacts to open, thus controlling the load circuit. When the control signal disappears, the transistor turns off, the relay coil is de-energized, and the armature returns to its original position under the action of the return spring, restoring the contacts to their initial state.

Classification

Based on the number of control channels, relay modules can be classified as single-channel, dual-channel, and multi-channel. A single-channel relay module has only one independent switching control channel, while dual-channel and multi-channel modules can simultaneously control the on/off state of multiple circuits.

Key Parameters

Taking TE Connectivity's 18220412 as an example, its coil voltage is 12V DC, the contact type is single-pole double-throw (SPDT), the maximum switching voltage is 250V AC/30V DC, the maximum switching current is 10A, and the operating temperature range is 40°C to +85°C.

Application Scenarios

Widely used in automation control systems, smart homes, industrial control, automotive electronics, communication equipment, and home appliances. For example, in smart homes, it can be used to control the power supply to devices such as lights and curtains; in industrial control, it can be used to control loads such as motors and solenoid valves.