Hi, If a DC coil needs suppresing you just put a diode across it and the transient spike when it is energised or de-energised is removed. W hat do you do to get rid of the transient spike with an AC coil ?
You can use two zener diodes back to back in series with a zener voltage greater than the power supply voltage. Also, there are ready two terminal devices called varistors or transient suppressors which are for this purpose.
