On Saturday, April 16, 2011 6:26:42 AM UTC-7, Karl Townsend wrote:
I built a serial port temp. sensor...
The unit uses DS1820 temp sensors and connects to the pc serial port.
There is a fifty foot run from the computer to the sensor.

My better half made me quit using it because of AM radio interference.
There is a constant beep beep beep.

Fortunately, the serial port has slew-rate limited signals and shouldn't be
an issue. The DS1820 (new ones are DS18S20) one-wire interface,
though, isn't so limited. If you use twisted pair wiring, and maybe a few
ferrite beads or 'clamp filter' units, it'll get better. To avoid ground
loops, ensure none of the distant end (sensor) wires touch any nearby
grounded metal.