Forum,
About a month ago I posted a question.
http://www.8052.com/forum/read.phtml?id=19252&top=
Reguading a Digital thermostat for use upto 1200 degrees F. There were some errors in the question I posed. Here it is again with some revisions.

I'm using a AT89C52 @ 11.059 Mhz. Among other tasks. It will input a value from the user to set the desired temperature. Also on demand it will display the current temperature of the block. I'm going to break this down into two blocks (reading the temp and controlling the temp).

First, I need to measure the temperature of a block of metal with a 500W 120V heating element in it. I have a Type "K" thermocouple to connect to the heated block. I figure that I should be able to measure a range of 70 degrees to about 1100 degrees. The thermocouple has an output of .843mV @ 70 degrees and 25.02mV @ 1117 degrees. I'm going to use ADC0804 to convert this voltage to digital format. There are some example circuits in the data sheet for the ADC, but I'm kind of confused about which one I should start with. One reads a voltage of 0 to 512mV but it looks like it requires a 15V source. I would like to stay with a single 5V source.

Controlling temp:
I would like to resolve the above problem before taking on this part, but here is what I have so far.
It was suggested that I use a CA3059 to switch the load of my heating element as it uses zero crossing. I think I would like to stay away from this part, one of the data sheets I have says it is obsolete and I've only found two places to get it. So, I'm pretty sure I've seen zero crossing triacs and I think I would rather use one of those. I'm not sure if I should vary the voltage to the element or to just switch it fully on and fully off to control the temp.
I've searched all over the place for how to build such a controller, but everyone want to just sell you one. I looked in places that related to heat treating ovens and ceramic kilns, but no go. Any more suggestions or ideas would be appreciated.

Thanks

Jon