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

[Sandy]

I have used 1N4007 diodes for this purpose and had no trouble!  The last 
relay I took care of was the keying relays in the old Navy "TCS-12" 
transmitter I have.  If you get across the key contacts when you are 
sending, the collapsing relay coil fields will give you quite a belt!  Diode 
installed and no more problems!

73,

Sandy W5TVW

----- Original Message ----- 
From: "Jack Smith" <jack.smith at cliftonlaboratories.com>
To: "'Elecraft'" <elecraft at mailman.qth.net>
Sent: Wednesday, April 08, 2009 1:22 PM
Subject: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber?


> 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
>
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