12vdc DPDT relays are common components in electronic systems that require the switching of power sources or the control of signals. These relays are designed to switch between two different circuits with a single control signal. In this article, we will discuss the wiring diagrams for 12vdc DPDT relays and how they can be used in various applications.
What is a DPDT Relay?
A DPDT relay is a Double Pole Double Throw relay that has two pairs of contacts that can be used to switch between two different circuits. Each pair of contacts is referred to as a pole, and the relay is referred to as Double Pole. Each pole has two positions, referred to as the Normally Open (NO) and Normally Closed (NC) positions. The relay is referred to as Double Throw because it can switch between two circuits, and each position is referred to as a throw.
When the relay coil is energized, the poles switch from their initial position to the other position. This makes the NO contacts close and the NC contacts open. When the relay coil is de-energized, the poles return to their initial position, and the NO contacts open while the NC contacts close.
Wiring Diagram for a 12vdc DPDT Relay
The wiring diagram for a 12vdc DPDT relay is pretty straightforward. The relay has six pins, with two pins for the coil and four pins for the poles. The pins are usually labeled on the relay body or given in the datasheet.
The pins for the coil are usually labeled as Coil+ and Coil-. These pins are used to apply a voltage to the coil to energize it. When the coil is energized, the poles switch position, as explained earlier.
The pins for the poles are usually labeled as Pole1, Pole1-NC, Pole1-NO, Pole2, Pole2-NC, and Pole2-NO. These pins are used to connect the circuit that needs to be switched between two different sources.
The wiring diagram for a 12vdc DPDT relay is shown below in Table 1.
| Pins | Description |
| Coil+ | Positive terminal of the coil |
| Coil- | Negative terminal of the coil |
| Pole1 | Common terminal of Pole1 |
| Pole1-NC | Normally Closed terminal of Pole1 |
| Pole1-NO | Normally Open terminal of Pole1 |
| Pole2 | Common terminal of Pole2 |
| Pole2-NC | Normally Closed terminal of Pole2 |
| Pole2-NO | Normally Open terminal of Pole2 |
Wiring a 12vdc DPDT Relay
The wiring of a 12vdc DPDT relay depends on the application requirements. However, some common wiring examples are given below.
Wiring for Switching between Two Power Sources
If you want to switch between two power sources, such as a battery and a DC power supply, you can use a 12vdc DPDT relay. The wiring diagram for this application is shown below in Table 2.
| Pins | Description | Wire Color |
| Coil+ | Positive terminal of the coil | Red |
| Coil- | Negative terminal of the coil | Black |
| Pole1 | Common terminal of Pole1 | Orange |
| Pole1-NC | Normally Closed terminal of Pole1 | Blue |
| Pole1-NO | Normally Open terminal of Pole1 | Yellow |
| Pole2 | Common terminal of Pole2 | Purple |
| Pole2-NC | Normally Closed terminal of Pole2 | Green |
| Pole2-NO | Normally Open terminal of Pole2 | White |
The wiring for this application is done as follows. Connect the positive terminal of the first power source to the Pole1-NO terminal of the relay, and connect the positive terminal of the second power source to the Pole2-NO terminal of the relay. Connect the common terminal of both power sources to the Pole1 terminal of the relay. Finally, connect the Pole2 terminal of the relay to the load, which can be a motor, a light bulb, or any other device that needs to be powered.
Wiring for Signal Control
The 12vdc DPDT relay can also be used for signal control. For example, you can connect a DPDT relay to a microcontroller to switch between two sensors. The wiring diagram for this application is shown below in Table 3.
| Pins | Description | Wire Color |
| Coil+ | Positive terminal of the coil | Red |
| Coil- | Negative terminal of the coil | Black |
| Pole1 | Common terminal of Pole1 | Orange |
| Pole1-NC | Normally Closed terminal of Pole1 | Blue |
| Pole1-NO | Normally Open terminal of Pole1 | Yellow |
| Pole2 | Common terminal of Pole2 | Purple |
| Pole2-NC | Normally Closed terminal of Pole2 | Green |
| Pole2-NO | Normally Open terminal of Pole2 | White |
The wiring for this application is done as follows. Connect one sensor to the Pole1-NO terminal of the relay and the other sensor to the Pole2-NO terminal of the relay. Connect the common terminals of both sensors to the Pole1 terminal of the relay. Finally, connect the Pole2 terminal of the relay to the input of the microcontroller. You can then use the microcontroller to energize the relay and switch between the sensors.
FAQ
What is the difference between NC and NO contacts?
NC stands for Normally Closed, while NO stands for Normally Open. The NC contacts are closed when the relay coil is not energized, and they open when the coil is energized. The NO contacts are open when the relay coil is not energized, and they close when the coil is energized.
How do I know which wire is which on a 12vdc DPDT relay?
The pins on a 12vdc DPDT relay are usually labeled on the relay body or given in the datasheet. The pins for the coil are usually labeled as Coil+ and Coil-, while the pins for the poles are usually labeled as Pole1, Pole1-NC, Pole1-NO, Pole2, Pole2-NC, and Pole2-NO.
Can I use a 12vdc DPDT relay to control AC power?
No, a 12vdc DPDT relay is designed to switch DC power sources. If you want to control AC power, you need to use a relay that is rated for AC power.
Can I use a 12vdc DPDT relay to switch between high current sources?
Yes, you can use a 12vdc DPDT relay to switch between high current sources, but you need to make sure that the relay is rated for the current that you want to switch.
What is the maximum voltage that a 12vdc DPDT relay can switch?
The maximum voltage that a 12vdc DPDT relay can switch depends on the rating of the relay. You need to make sure that the relay is rated for the voltage that you want to switch.
Conclusion
12vdc DPDT relays are versatile components that can be used in various applications to switch between two different circuits. The wiring diagrams and examples given in this article should help you understand how to use these relays in your own projects. Remember to always check the rating of the relay before using it to switch power sources or signals.
