Yes, it actually goes deeper than just a snubber diode. My problem,
which I did not explain further is that I have to deal with the best
solution for a board already built (that's were the SOT23 came into it).
ie. There is no diode in the circuit now. As for the EMI, there are ways
of 'controlling' the EMI but keeping lead lengths short is usually the
first start. Thanks for the help folks.

Spehro Pefhany wrote:

> At 06:06 PM 2/28/02 -0500, you wrote:
>
>> Note: As good engineering practice, it is ALWAYS a good idea to put a
>> snubber diode across and inductive (relay) load to prevent the unwanted
>> transmission of spikes into the air and or circuit not just to prevent a
>> damaging inductive spike.
>
>
> It's more "conventional" than "good" design practice. If no thinking or
> analysis goes into it, it's not really engineering, and is sometimes not
> good practice.
>
>> This diode must be placed as close to the relay as
>> possible. Any lead length or circuit trace longer than an inch will
>> always
>> radiate somewhere in the RF spectrum and may cause interference.
>
>
> Are there any other ways to control EMI? What layout parameter is more
> important than trace length in predicting EMI emissions or susceptibility?
>
> Best regards,
>
> Spehro Pefhany --"it's the network..."            "The Journey is the
> reward"
> speff@interlog.com             Info for manufacturers:
> http://www.trexon.com
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> http://www.speff.com
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>
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>
>

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