Dual Channel 12v Relay Driver Board Circuit

Overview

In today's tutorial, we are going to make a "Dual Channel 12 Volt Relay Driver Circuit" using BC547 Transistors.

A simple and user-friendly method for interfacing two relays for switching applications in your project is provided by this relay driver. This driver enhances the input impedance using a standard BC547 NPN transistor (or an equivalent). It is a widely used driver capable of driving various types of relays, including reed relays. Transistors Q1 and Q2 function as a basic common-emitter amplifier, significantly boosting the sensitivity of the 12-volt relay coil by approximately 100 times. In simpler terms, the current gain for this circuit is 100, effectively reducing the relay sensitivity to just a few volts. To ensure safe operation, resistors R3 and R4 limit the input current to Q1 and Q2 within a safe range. Additionally, diodes D3 and D4 serve as electromagnetic field (EMF) dampers, filtering out any sparking that may occur when the relay is de-energized.

Hardware Components

To make Relay Driver Circuit, you'll need the following hardware components to get started:

Schematic

Specification:

• Input - 12 VDC @ 84 mA
• Output - two SPDT relay
• Relay specification - 5 A @ 230 VAC
• Trigger level-2~5VDC
• Berg pins for connecting power and trigger voltage
• LED on each channel indicates the relay status

Conclusion

This Dual Channel 12V Relay Driver Board Circuit offers a straightforward and efficient solution for interfacing two relays in switching applications. By utilizing a common-emitter amplifier setup with transistors Q1 and Q2, the circuit significantly enhances the sensitivity of the 12-volt relay coil, making it capable of driving various relay types including reed relays.