GM Coolant sensor

[dzorde at aesprodata.com.au]

     Thanks, nice reply, I would go digital if I had the time, but I just 
     want something quick and super reliable (the more parts, the lower the 
     MTBF).  Anyway I'll just mount a VDO temp sensor in a larger plug 
     (isolated with the extra resistor to the earth, to turn it into a PTC 
     sensor).  One of these mounted in each area to be measured, a selector 
     switch to select either sensor and a panel meter to display the 
     selected sensor.  Easy, quick, cheap and very reliable.  Thanks for 
     the input everybody, its good to see some of the ideas floating 
     around.
     
     Dan        dzorde at aesprodata.com.au 
     
     <snip>
     
Now, to answer your real question re: pos. coeff. temp. sensors.  Thermistors 
are neg. coeff. but T.I. used to make a product called a 'sensistor' that
was pos. coeff.  (last time I saw one was probably 1972).  Don't have 
any idea if they still make it.  There is a company called Omega that 
carries all kinds of stuff like that (and produce very good catalogs 
and reference sources).  Their number is 800-826-6342.  (But, you'll 
still probably have to condition the output -- i.e. use an op-amp!)
     
Tom