>> identified the 1N4148 across a telecom relay as the primary problem.
>
>I always thought signal diodes were a little fragile in this
>application, and tend toward 1n400x rectifiers instead.

That is my gut feeling too. Having used diodes in exactly this manner for a
long time, I suspect that this failure of 1n4148's is more related to some
detail about the relay.

>But based on your first message, if speed is an issue, they
>might be worse.  But if the diodes blew in that design, that's
>not a diode speed issue, is it?

I suspect it may be more to do with the magnitude of the current flow
through the diode.

>And are the protection diodes in something like a ULN2003
>that much faster than discreet diodes, or are they just
>useless marketing ploys?

These may have started off as a parasitic diode in the chip, but someone saw
the possibility of having them included as catch diodes, so built in
appropriate ones.

>Sigh.  I though I knew what I was doing, and now I'm all confused!

<VBG> but isn't that normal for us lot ... ???

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