electrical / electronics

Instrumentation Measurement & Lab

Midterm

1. A temperature sensor is exposed to a sudden change of 20oC to 80oC. 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 25oC reference.

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

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

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?

b. What input is required to get a zero volt output?

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