Page 26 of your Text Book; Solve/answer Problems 1.1, 1.2, 1.4, 1.6, 1.7, and 1.9

1.1 Identify the sensor, signal conditioner and display elements in the measurement systems of (a) A mercury in glass thermometer(b) A Bourdon pressure gauge(a) Mercury in glass thermometer:First to analyze which is the sensor, the signal conditioner and the display elements, the components of the thermometer need to be identified.

URL: http://www.visualdictionaryonline.com/science/measuring-devices/measure-temperature/clinical-thermometer.phpThe sensor in this case will be the mercury since its the element of the thermometer which reacts to the change in temperature, followed by providing the measured temperature. Regarding the signal conditioner, the constriction will work as a manipulator which will make the reading of the thermometer more accurate when its taken out of the body in which the temperature is being measured. Finally the display element, will be represented by the scale, since its the component of the thermometer that displays the temperature measured by reading the height of the mercury in the capillary tube.(b) Bourdon pressure gaugeSimilarly to the thermometer the components of a Bourdon pressure gauge are shown below.

URL: http://en-co.wika.de/landingpage_bourdon_tube_pressure_gauge_en_co.WIKAIn this case the sensor will be represented by the bourdon tube itself, since it converts the pressure of the fluid into a motion that then the gear assembly (composed of links, toothed segment and gears) will transform into rotation, due to its function the gear assembly can be categorized as the signal conditioner. Finally the display elements will be composed of the needle and the dial along with the scale.1.2 Explain the difference between open and closed loop controlIn a closed loop system to output signal does have an effect on the input signal, modifying it to maintain an output signal at the required value. In an open loop signal the output signal does not affect the input signal.1.4 The automatic control system for the temperature of a bath of liquid consists of a reference voltage fed into a differential amplifier. This is connected to a relay which then switched on or off the electrical power to a heater in the liquid. Negative feedback is provided by a measurement system which feeds a voltage into the differential amplifier. Sketch a block diagram of the system and explain how the error signal is produced.1.6 Explain what is meant by sequential control and illustrate your answer by an example.A sequential control is a control which is predetermined to follow a set of steps. The order of the steps is set when the controller is designed and these steps are followed by the controller to perform the task. An example of a sequential controller will be present in a refrigerator where the program follows a set of steps in order, for example, once the fridge senses an increase in temperature, it engages the program to turn the compressor on followed by the fan which cools the inside of the fridge, once the fridge reaches the desired temperature the system shuts off.

1.7 State steps that might be present in the sequential control of a dishwasher.1. The user inputs information on the dial about which cycle the machine should run at. (i.e. whites, delicates, or cold wash are examples)2. The machine senses the position of the dial.3. A signal conditioner takes this signal and converts it to something the machine can use, the cycle its set to.4. The machine then runs the cycle according to the predetermined settings of that cycle. 1.9 Compare and contrast the control system for the domestic central heating system involving a bimetallic thermostat and that involving a microprocessor.The domestic central heating system involving a bimetallic thermostat is switched on or off by the bending of a bimetallic strip which changes as the temperature changes. The heating system involving a microprocessor is operated by a thermo-diode as the sensor. The microprocessor is more accurately controlled and can be programmed to select different temperatures at different times of the day.