Maybe you shouldn't had said 50th but we won't tell.
Could the EM2 use LM34 temp sensors? They give 10mv/deg. F and have
very good accuracy (spec is 1 degree but I get less than .1 degree repeatability
one sensor to another)and track well, very linear. They are what I am
using, just JB welded into a hollowed out old sensor and plan on using for oil
and water temps.
Fine points on the EM2:
The default sensors on the EM2 are very low cost automotive types but
they are not inherently super accurate. Usually there in no big
down-side for the water or oil temp to be off a few degrees so most
builders need not go any further. If the water temp turns out to be
actually 178 instead of 180, no big deal. Super accuracy can be
had with these sensors if you go to the trouble of calibrating the instrument
but then you must get into the nitty gritty of the calibration procedures and
the troubles can begin.
But here is where it does matter. If you are calculating thermal
loads and heat dissipation based on differential temps (let's say water temps
in and out of the radiator for instance) a few degrees of error can make
your results meaningless. In this example, it is not uncommon for the
Delta T to be in the range of 10 degrees at some power settings. If the
error in temperature is a couple of degrees, the error is huge, especially if
the errors are in opposite directions.
Bottom line is, if you need very accurate readings, learn to
calibrate the EM2 if that is what you are using. To do this, you need a
good reference. The easiest way is to use a non-contact (infra-red)
thermometer. Harbor Freight and others are now selling inexpensive ones
for about $10.00. No reason for any airplane builder not to have
one. Be sure to paint the test points on the part to be
measured with a spot of flat black paint to eliminate emissivity errors.
Tracy (should I have said 50th? )