[Elecraft] Can a 1N4007 Be an Effective Relay Snubber?

[Jack Smith]

To answer, I hope definitively, the question "is a 1N4007 power diode 
too slow to be used as a relay coil snubber," I've updated my December 
2007 diode turn-on time measurements with data taken this morning 
showing the effectiveness of (a) no snubber; (b) 1N4148 snubber and (c) 
1N4007 snubber with a typical small relay switched by a 2N7000 MOSFET 
transistor. I've also looked at the how much the relay release time 
lengthens when a snubber is added. (Of course, the specifics are 
dependent upon the particular relay but the concepts are similar.)

The details are at http://www.cliftonlaboratories.com/diode_turn-on_time.htm

The "Cliff's Notes" version is that the turn-on (note I said  turn-on, 
not turn-off) time of a 1N4007 diode is sufficiently fast to be a very 
effective relay snubber. The data also shows that a diode or MOV or 
other technique should be used to control inductive field decay voltages.

Jack K8ZOA
www.cliftonlaboratories.com