Can I drive a relay with a transistor?

ID: FAQE10040E



DC coil relays can be driven by transistors.
However, the back electromotive force generated by the coil when it’s turned off may cause damage to the semiconductor or device malfunction. As a countermeasure, add a surge-absorbing circuit to both ends of the coil.


For more about protecting relay coils from surge, refer to FAQE10041“What are surge countermeasures in coil relays?” and Safty Precautions for All Relays: 2-2-5 Preventing Surges When the Coil Is Turned OFF.

Quick tips

If a surge-absorbing circuit is added, the relay release time will be longer. Check the circuit before use.

We have prepared a technical support page dedicated to high-capacity relays that explains in detail "I don't know" when using high-current, high-voltage PCB power relays, such as back EMF voltage (Zener diode and varistor) of the coil, holding voltage application circuit, recommended conditions for high-current substrate flow solder, the influence of magnetic fields, and precautions when connecting in series and parallel. Please also use this as well.
Click here for the high-capacity power relay technical support page.

Product category Relays Signal Relays Power Relays
Classification Usage, Applications
Related keywords
  • Signal Relays
  • Power Relays
  • Transistor Drive
  • Back Electromotive Force
  • Surge-Absorbing Circuit

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