Homebrew_PCBs

That will work just fine, but unless you use a transistor with a metal case, your upper temperature will be limited to 150°C, or possibly lower. If you use a metal case transistor, remember that the collector is connected to the case, and this may cause a grounding problem. Temperature limit with the metal can is 200°C or lower. Look at the datasheet for the maximum storage temperature, and use the lowest current through the transistor you can.

 

A transistor with two of three legs soldered together makes a temperature probe. Is 

the temperature inside of lam too hot? Google for temperature probe circuits like I 

do for other projects.