pdf at http://en.wikipedia.org/wiki/Thermistor Calculate the Humidity Sensor resistance at 30°C T = 273.15°C +30°C = 303.15°C T0 = 273.15°C +25°C = 298.15°C R60% 30°C =25.5858 kΩ - Matlab code: 33*exp(4600*(1/303.15-1/298.15)) = 25.5858 Calculate the Humidity Sensor resistance at relative humidity 70% See the above graphic for the standard resistance: Exercises - Solutions 3 R60% 25°C =33 kΩ, R70% 25°C =12 kΩ R70% 30°C=( R60% 30°C * R70% 25°C =)/ R60% 25°C =9.2 kΩ Or RH = 9.2 kΩ, give RT = 50 kΩ VO = RH/(RT+RH)*2.5V = 0.388 V Question 3 Given the following bridge circuit for a strain gauge, determine the value of the strain gauge resistance {RS}. Let: VIN = 5V R3 = 200 Ω R2 = 50 Ω R1 = 100 Ω a) Under no strain. b) When VOUT = 0.5 V {under strain}. Solution: a) Under no strain: R1 R3 R1R4 R2 R3
Question 1 Name 9 characteristic parameters of sensors. Treshold, noise, range, stability, linearity, accuracy, precision, sensitivity, hysteresis Question 2 Given the circuit below (using a SYH-2R humidity sensor) determine the output voltage for a relative humidity of 70 % at 30 °C if R T = 50 kΩ and VDD= 2.5 V. R70 30 c =R H =9,2 kV RH 9,2 k V O= ∙ V DD= ∙ 2,5 = 0,388 V (R T + R H ) ( 50 k +9,2 k ) Hint: Check specification for Humidity Sensor of SYH-2R.pdf at http://www.rhopointcomponents.com/images/SYH-2R.pdf 2 Week 04 Homework Question 3 Given the following bridge circuit for a strain gauge, determine the value of the strain gauge resistance {RS}. Let: VIN = 5V
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