On Wed, 13 Feb 2008 23:46:43 GMT, Winston
wrote:

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.
(...)

http://www.amveco.com/pdf/AC1020_11-01.pdf
http://rocky.digikey.com/WebLib/Amve...15,AC-1020.jpg

This is Digikey TE-1020-ND, a current transformer. Its small and will fit within a 1" cube.
Disconnect the defrost heater and thread its wire through the hole in the middle of this
part, then reconnect it. Solder a 100 ohm 1/8W resistor across the output of the
transformer. Every amp flowing into your defrost heater will now be indicated by a
voltage of about 0.1V AC at the output of the transformer, across the resistor.

Connect one of these loggers (US$25.00)to the output of your current transformer and log
the data to your PC.

http://www.dataq.com/products/startkit/di194rs.htm

That's what I would do.

--Winston


Wouldnt it be better to use a thermistor and have it actually tell if
there is a temperature change, rather than just power on the heating
coils? If you have an open in the coils..you will have power, but no
heat.

Gunner



"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner