I’ve been fascinated by the LM335 for some time -maybe my obsession with stability finally gave way to my fascination with a circuit with intentional thermal drift. I finally bought some the other day, and to check one out, I hooked it up as a thermometer, based the National Semiconductor application note.
The circuit consists of two parts: The LM335 and its adjustment. The output of the LM335 is 10 millivolts per degree C, with 25 degrees C corresponding to 2.982 VDC. A reference circuit provides a zero reference voltage. It is adjusted to (2.982 volts – (25 degrees x 10 millivolts/degree) = 2.832 volts. To read the temperature of the LM335 directly in degrees C, connect the + lead from a high impedance DVM to the output pin and the – end of the DVM to the 2.732 volt pin.
The factor of 10 millivolts per degree C is equivalent to 10 millivolts per degree K, since a change of one degree C is equal to a change of one degree K. The difference in the two scales is only their offsets. The melting point of water ice is 0 degrees C and 273.15 degrees K. The boiling point of water is 100 degress C and 373.15 degrees K.
Read More Source:http://www.cappels.org/dproj/lm335th/LM335thermometer.html
Thank you.
Related Links
More circuit Temperature Meter
More circuit by IC LM335
More circuit Temperature Control
Car Temperature Gauge by IC CA3162 + CA3161
Digital Measurements Temperature by LM335
This entry was posted on Friday, August 10th, 2007 at 11:03 pm and is filed under basic electronics, Electronic Control, meter.
