Re: Re: Re: Optoisolation for a modem

Jim Fackert wrote:

> From: "Jim Fackert" <jfackert@...>
>
> So the impedance of the resistors is adequate, with the strike shorted
> to
> ground, to limit the voltage and protect the parts, adn you DON'T
> want them
> to open up like fuses!

No, I don't think a 10 Ohm resistor is enough to limit the current of a
1000 V or higher spike! I DO
want them to open up, like fuses, and quickly! I'd use a higher value,
but it will start to affect the
line characteristics.

>
> James wrote
> >in this application carbon comps
> > have a tendency to stay together and will pass dozens of simulated
> part
> > 15 lightning strikes. It will also pass at least a couple of real
> ones.
> > Carbon films have a tendency to arc over and open up. Nothing wrong
> with
> > that so long as you don't mind replacing them.

I'm not worried about part 68 compliance, this is in my own home. Part
68 says that the
phone must not go up in flames, eject fragments beyond the housing,
etc. The phone
does NOT have to work after these tests! And, the pictures I've seen
tell me, THEY
DON'T! They get fried, good.

Jon