To reverse the direction of a motor using a switch, you typically need a specific type of switch wired in a particular way, especially for DC motors.
The Essential Switch
For reversing the direction of a DC motor, a standard on/off switch isn't sufficient. According to reference information, reversing DC motors requires a specific type of switch: a DPDT (double pole, double throw) switch.
- DPDT Explained:
- Double Pole: It controls two separate circuits simultaneously.
- Double Throw: Each circuit can be connected to one of two different points.
- Many motor control applications use a DPDT switch with a center-off position, allowing the motor to be stopped between reversing directions.
Understanding the H Bridge Configuration
Simply having a DPDT switch isn't enough; it must be wired correctly. Reversing DC motors requires the DPDT switch (center off) wired in what is known as an 'H Bridge' configuration.
- Why "H Bridge"? This configuration gets its name because, when viewed in a schematic diagram, the arrangement of the switch and motor resembles the letter 'H', indicating the path of current flow.
How it Works: Reversing Polarity
The H Bridge configuration wired with a DPDT switch works by reversing the polarity of the voltage applied to the motor terminals.
- When the switch is in one position, power flows through the motor in one direction.
- When the switch is flipped to the other position, the connections to the motor terminals are swapped, causing power to flow in the opposite direction.
- This reversal of current flow causes the DC motor to spin in the opposite direction.
In summary, to reverse a DC motor's direction using a switch, you need a DPDT (double pole, double throw) switch (often center off), correctly wired in an H Bridge configuration to reverse the voltage polarity across the motor.
