I am builing a homemade reflow oven, but I cant find a good and cheap temperature sensor that can survive the temperatures necessary for reflow (~250ºC or 482ºF). Does anyone have a recommendation? I will be reading the output in a PIC ADC to control a relay.
In my home-brew reflow oven I used a PT-1K (1K Ohm at 0C) sensor. Much easier to interface than a thermocouple. I preferred it over the more common PT-100 type (100 Ohm at 0C) because the resistor values can be higher, which avoids self-heating, and makes wiring resistance less of a problem.
Thermocouples (such as type K) are good, cheap and (depending how their wires are insulated) easily cover more than the range of interest. They do need a stage of amplification before the ADC, however. Suppliers and circuit examples should be easy to find.
And probably you'll never find a silicon-based plastic-packaged pcb mounted sensor, if it's this what you're looking for. For the basic reason those temperatures are extreme for electronic components
Have you heard about thermocouples? Maybe the oldest electronic temp sensor... still widespread in industrial environments. Take for example a type J. They go up to 750 C. Not enough?
RTD would the best solution for the range of (<500 c).
A decent Reference