Hi Orin,

> 
> On 3/21/07, Vasile Surducan <piclist9@gmail.com> wrote:
> > Based on drawing  ES-I is input and E_O is output and here the
> > protection could be OK.
> > Orin, a stabilizer circuit (even the three terminal one) has a
> > negative feedback, so the voltage can't grow to 11.4V even in bad
> > dreams. If the supply is based on a three terminal stabilizer the
> > reverse diode between Vin and Vout will become on and the spike will
> > be absorbed in the filtering cell.
> 
> Well, that all depends on Vin to the regulator which is undefined...
> as you note, the supply schematics aren't given.
> 
> Then the problem being protected against was a short to 12V, not just
> a spike.  What if Vin to the regulator is the same 12V?
> 
> Orin.

It's currently a 7805 regulator. 

If I had designed the board with through hole parts I'd just suggest
that the processor be in a socket.  But it's SMT and so a little more
effort is needed to prevent that accidental zap when someone is first
wiring up their lathe.

John Dammeyer

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