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How Do I Use a Relay Module to Control Actuator Direction with Arduino?

A dual-relay module is the simplest way to control actuator direction from an Arduino — no H-bridge IC required. Relays switch the full 12 V / 24 V motor current directly, making them reliable for high-current applications like the PA-17.

When to Use Relays vs H-Bridge

Feature Relay Module H-Bridge (L298N / IBT-2)
Max current 10–30 A (depends on relay rating) 2 A (L298N), 43 A peak (IBT-2)
PWM speed control No — on/off only Yes — variable speed via PWM
Cost Very low (~$3–5 for dual relay module) Low–moderate ($3–15)
Best for High-current actuators, simple extend/retract, PA-17 Speed control, feedback positioning, lower-current models

Wiring a Dual-Relay DPDT Configuration

You need two SPDT relays wired to form a DPDT (double-pole double-throw) H-bridge equivalent. When Relay 1 is energised and Relay 2 is off, current flows in one direction through the motor. When Relay 2 is on and Relay 1 is off, current reverses.

⚠️  Never energise both relays simultaneously With both relays on, positive supply connects directly to negative — a dead short. Always ensure a brief delay (20–50 ms) between de-energising one relay and energising the other. This is called a "shoot-through prevention" delay.

Captura de Pantalla 2026-03-10 a la(s) 13.58.36

Flyback Diode Protection

DC motors are inductive loads. When power is cut, the motor generates a voltage spike (back-EMF) that can damage relay contacts over time. Place a 1N4007 flyback diode across the motor terminals (cathode to positive terminal) to absorb these spikes and extend relay life.