[Lowfer] RE: Lowfer digest, Vol 1 #276 - 4 msgs

[W1EOF]

> The serial port on a computer can swing +/- 12 volts, so I wouldn't
connect
> it directly to the Epson oscillator. Probably there are internal
protection
> diodes in the Epson, so it might be OK if you put a large resistor like
50k
> in series. But I'd key it from the parallel port instead, because the
> parallel port output only swings from 0 to 5 volts. Still wouldn't hurt to
> put a fairly large resistor in series.
>
> Lyle, K0LR

IMHO I'd go one step further and use an opto-isolator between the two. It
just might provide that added bit of isolation to save the computer during a
thunderstorm.


73,

Mark W1EOF