Trying to make an RTD that also duals as a heater

[Tdunlap]

Hello,
What i need to do is; create an RTD sensor, hook it into a MCU and use the mcu and the self heating aspect of the RTD to maintain a constant temperature.

I attached 3 files: the first is the circuit running under normal load of .001A, the second is of the housing for the rtd itself (i made it, so be gentle), the third is the circuit again at 10A, used when its supposed to be heating. This is just the first part of the circuit, without the means of inputing it into a mcu.

A side note, the power supply is held at constant current.

The center is meant to hold a sample for an experiment. The channel that runs around the outside of the center opening is there to house the bare coiled wire that will run through the block. The metal is copper since i couldn't afford platinum.

My biggest worry is; when i try to up the amps, i will blow out the components, since most are rated at 1/2 watt.

Any help on how to reduce the changing resistance down to a point where it can be taken by the MCU would be appreciated. (the circuit is setup so that the resistance of the the rtd is outputted as voltage of the same magnitude.)

Also i didn't not design this circuit, i got it from an example from microchip.

Thanks in advance.

 

[uart]

Cool. Where can I buy one of those opamps that produces a 1MV output while using only a +/- 5 volt supply.

 

[Tdunlap]

Cool. Where can I buy one of those opamps that produces a 1MV output while using only a +/- 5 volt supply.

Im getting sarcasm from this... Sooooo helpful.

Thanks.