Recommended
#183: Why diodes are used around relay coils: Back to Basics on flyback or snubber diodes
Why people recommend it
Repeatedly linked to show, with real scope traces, why a diode goes across a relay or motor coil and how large the voltage spike gets.
Watch for: shows real waveforms, so good for visual learners
In their words
For a great demonstration and explaination, have a look at this video by w2aew:
tehwalris on electronics.stackexchange.com, Dec 2014. CC BY-SA.
But you may want to watch this video to see actual waveforms and how diode protection works.
ayazar on electronics.stackexchange.com, Dec 2014. CC BY-SA.
In this video on flyback diodes on a relay ([video] ) the speaker says that a 1N914 or 1N4148 would work, as wood 1N400x, but he likes the switching diodes better because they are faster.
Mark Colan on electronics.stackexchange.com, Jun 2017. CC BY-SA.
