Questions concerning thermistors

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SUMMARY

This discussion centers on the functionality and application of thermistors, specifically addressing their resistance values and the significance of the b-constant. It is established that thermistors vary their resistance with temperature, which can be utilized in temperature-actuated circuits. For on-off control applications, users can implement thermistors directly in series with a zener diode or utilize differential amplifiers for proportional control. Resources such as the National Semiconductor Analog Circuits Handbook provide valuable circuit design examples for effective implementation.

PREREQUISITES
  • Understanding of thermistor resistance values and their implications
  • Familiarity with the b-constant in thermistor specifications
  • Knowledge of operational amplifiers and comparators
  • Basic circuit design principles for temperature control applications
NEXT STEPS
  • Research the function and calculation of the b-constant in thermistors
  • Learn about differential amplifiers for temperature sensing applications
  • Explore circuit design using zener diodes with thermistors for on-off control
  • Review the National Semiconductor Analog Circuits Handbook for practical circuit examples
USEFUL FOR

Electronics enthusiasts, circuit designers, and engineers interested in temperature sensing and control applications using thermistors.

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I've got some rather simple questions concerning thermistors. First, in viewing spec. sheets I only see one resistance value. What is that value telling me? In some of the specs there is something called a b-constant. What is that? Does a temperature actuated circuit demand an amplifier to take the small changes in resistance and produce larger voltage fluctuations? or can you just use them directly in series with a zener to make a temperature actuated switch? Basically I know little more than the general idea that they vary their resistance with temperature. Any answers, information, etc. would be much appreciated. Thanx for your time and patience with my ignorance.
 
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Most applications use the dR/dT----> dV/dT about a nominal value to drive a differential amp for proportional control, Or use the voltage drop and a windowed comparitor w/hystrerisis for on-off type control.
 
Yea, all I need is an on-off type deal.
 
If you have access to an national semi analog circuits handbook, there is a lot of good examples, otherwise, radio shack sells these small and really nice, circuit design handbooks, I think op-amps and comparators are in the same book, good designs that work and can be built quickly.
 

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