The local supply bypass capacitor needs to connect from the coil supply to the FET source and the diode directly from the coil supply to the FET drain. This constrains the switching transient within the triangle of those three components.
Of course.
I believe you stated, not explained. Can you put some numbers to your claim?
Well, whatever a “typical Arduino user” is, designs that crash the microcontroller when a relay is (de)activated, are a moderately common topic here.
My statement was to satisfy more advanced folks who know the suppression can be accomplished with a resistor and capacitor and/or combinations of diode, zener, resistor, capacitor. I also thought it was diversionary to mention the dynamic changes of a relay, motor etc resulting from the use of a diode for suppression.
Regarding your insistence the wire leads are of major concern to a hobbyist. Can you put some numbers to your assertation?
see wire transient voltage
Also can you suggest why in this type of application transmission line response applies?
So you know, I only responded to your obfuscation of the simple need to address the "flyback" voltage resulting from turning off an inductive element.
I've designed enough products that have met automotive, military and circuits carrying classified information to know what is really important. BTW I never used a feed through filter, they are a non technical persons way out.
So if you are such and authority on EMC then go look at the typical Bulk Current Injection EMC test and suggest how one might pass this test with a circuit packaged in a plastic housing.
I'm done with this topic. In fact I'm embarrassed I helped drag it this far..... 