> The relay, being an inductor, will "want" to keep the same amount of
> current flowing and will do anything it can to make that happen. It'll
> ramp it's voltage up so that the current continues to flow. 
> It's during
> this time of going from reverse biased to forward biased that the
> voltage "spikes"; and you can EASILY see voltages WAY above the power
> supply voltage. 

Yes, but at that moment the diode is either conducting or on the eve of
conducting. Maybe a very fast switch-off could produce a high-enough
spike to harm the diode. Sideline: does a diode spec mention a maximum
*forward* voltage?

I very much doubt the standard saturated biplar transistor will switch
off faster than the reaction time of an 1N4148.

Wouter van Ooijen

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