[R-390] AC Line Monitoring Musings

[John Kolb]

On Wed, 23 Jul 2003, Drew Papanek wrote:

>
> One could easily assemble a voltage monitoring system using an RS-232
> computer-controllable DVM (about $60 from RadioShack, more from other
> sources).  The DVM connects via a standard cable to a PC's serial port and
> includes software for the PC.  I don't know if the software performs
> periodic data logging.  (Perhaps a job for a little QBasic code and that old
> 386 you've got sitting around collecting dust.)
>

If building such a system, I'd measure the output of a transformer,
not plug the DVM leads directly into the power line - potentially
a large short circuit if the common lead of the DVM goes to common
of the serial port, and is plugged into the hot side of the power line.

John