Week 4: Instrumentation and process control Midterm

Week 4 Midterm

1.    A temperature sensor is exposed to a sudden change of 20^oC to 80^oC. The sensor outputs 0.02 volts for every ^oC of temperature and has a 2.3 second time constant.

a.    What is the sensor output voltage at 1.5 seconds?

b.    At what time, t, does the sensor output become 1.0 volt?

2.    A sensor, R, that changes resistance is used in a bridge circuit as shown below.

a.    What sensor resistance, R, will null the bridge?

b.    What is the off-null voltage if R changes by 0.5 Ω?

3.    A measurement system has noise above 20 kHz and the data signal frequency is between 100 and 500 Hz. Design an RC filter that reduces the noise by 95%, i.e., only 5% is left. Show the schematic and the component values.

4.    Given a Type J TC with a 25^oC reference.

a.    What is the temperature if the TC voltage is 22.87 mV?

b.    What voltage would result from a temperature of 225^oC?

5.    A 10-bit ADC has a 5.00-volt reference.

a.    What binary output is produced by an input of 3.04 volts?

b.    Suppose the output is found to be 1F4h. What is the possible input voltage?

6.    A 12 bit bipolar DAC has a 10-volt reference.

a.    If the hex input is 5D7h what is the DAC output voltage?

What input is required to get a zero volt output