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  • Publicado : 28 de febrero de 2012
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The purpose of this experiment is to study a few mechanical sensors that work on the principal of a change in resistance in order toacquire experimental data. The thermistor and potentiometer are two examples and will be the focus of this experiment. However not most data acquisitionsystems are set up to measure and acquire resistance directly but voltage instead. As a result, sometimes signal conditioning is required to convert thechange in resistance into the change in voltage.
A teapot was filled close to full and the temperature control was set to the lowestsetting with the thermistor placed in the water. The ambient temperature of the air was recorded as well as the initial voltage which was zero. Thenthree resistors were chosen with same nominal value as the thermistor. A breadboard was then used along with the thermistor and a power supply toconstruct a wheatstone bridge. After that, the DC power supply was turned on. The temperature and voltage were then recorded every time the nob of thetemperature control on the teapot was turned to the next setting. For activity 2 the potentiometer was connected directly to the DMM which was set to readresistance. Then the resistance was measured for knob positions from 0% to 100 % every 10%. This was repeated twice. The DMM was them removed and a 10kΩ was attached in series with the rotary potentiometer and the DC power supply. Then the output voltage was recorded the same way it as before.

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