On Feb 13, 2:21 pm, Dan@ (Dan ) wrote:
I know this is off topic, but I know some of you know the answer.

I need to monitor the temperature of a heating element. I need to know
when it is on and when it is off. I don't need to know the
temperature, just that when it is getting hot and when it is not hot.

It is the defrost coil on my freezer. I have had more than one defrost
controller fail. One failed at Christmas and one at Thanksgiving. I
would like to monitor the temperature of the coil using my PC over
time so I can see that the temperature has increased and then
decreased over some time, probably 24 hrs.

When the defrost controller fails, the freezer freezes up over a 2
week period. If I can find a way to verify that the heating element is
heating or not, I can tell if I'm headed for trouble.
This is a 5-year-old Maytag. Expensive, so throwing it out isn't an
option. I just want to see a freeze-up coming. I have a spare
controller. I just need to know when the existing one failed.

I would like to monitor this with a PC input device that can handle an
input of some kind. Like an RTD or even a 120VAC pulse. The controller
switches the element to ground so I'm not sure how to pickup the 120
pulse.
I know you smart guys can come up with something I can use to see that
this dam thing is heating and defrosting the freezer coil.
Thanks Guys,

Are you capable of writing the software necessary to monitor an
external device? what sort of PC? An old one running DOS is a piece of
cake if you use the game port, or even a serial port and one of the
RTS/CTS pins. You might even get away using one of the input pins on a
parallel printer port.

If you want it to be monitored using a Windows based computer, then it
gets a wee bit more complicated. Perhaps what would be easier and
cheaper would be a freeze monitoring device with an alarm bell.

Paul