Terry,

I developed the polymer ptc heater used in auto side mirror defrostng
heaters. There are some
patent references in my engineering link below. (click links)

I think what you are refering to though is a ceramic device commomnly used
for
motor overtemp protection and tv crt degaussing. It is about the size of a
quarter...
and costs about a quarter in large quantities. MuRata makes a lot of them.

Les Watts

http://www.lmwatts.com

"Terry" wrote in message
om...
Is anyone familiar with a small heater ( dime or quarter size ) that
will heat to a set point and then hold
that temp without a thermostat. I had some samples of them a few years
back but can't remember the
company that made them or what they were called.

Terry