Electronic – Flyback protection for a DC latching solenoid


I'm looking for a solution for "flyback" protection when driving a 2 wire DC latching solenoid. You cannot use the traditional diode solution as the polarity of the coil is reversed to open or close the solenoid.

My CCT uses two relays to switch the solenoid – the first (SPST) applies power to the second relays contacts (DPDT) which does the polarity reversal for the power to the solenoid coil.

Of course my relay coils already have conventional flyback diodes connected – what I'm looking to protect against is the back EMF from the actual solenoid coil itself.

Best Answer

You can use four diodes to the supply rails like for motors in an H-bridge.

See for example here.