Awareness | QIO-GP8x8 Diode Requirements

Learn the diode requirements for the QIO-GP8x8.

Updated at September 25th, 2023


  • Due to the characteristics of inductors (the coil), the coil can send damaging voltage spikes into the circuit when de-energized.
  • A “flyback” diode and resistor is a good solution to sudden voltage spikes. Sometimes these items are built into the relay housing, but sometimes they must be added externally.
  • The specification sheet for the specific relay model may need to be consulted if the customer is not sure.
  • Many spec sheets will suggest the diode type, connection details and resistor values for proper long-term operation.
  • As diodes are polarity-sensitive devices, it is important that the relay is connected to Q-SYS in the way shown.


The lack of diode or proper polarity WILL NOT prevent the relay from working at all, it will only increase the likelihood of damage to the Q-SYS GPIO over time.