A relay is an electrically actuated switch. Most use an electromagnet (coil) to operate one or more switches. Relays are used where it is necessary to control a circuit by a separate low-power signal, or where several circuits must be controlled by one signal. They were used a lot in telephone exchange and railway applications.


Related to the electromagnet:

  • Coil voltage (maximum rated voltage to operate the coil, V)
  • Coil resistance (resistance, Ω)

Related to the switching contacts

  • Maximum switching voltage (V)
  • Maximum switching current (A)

Please pay attention to the type and number of contacts.

Advice: When implementing a relay, make sure you always add a small diode over the coil in the reverse direction to eliminate back-EMF generated voltages (flyback diode).