Pressure Sensors are always pushed around Click within the blue frame to access the control panel. Only use the control panel (at the bottom of screen) to review what you have seen. This presentation is partially animated. When using your mouse, make sure you click only when it is within the blue frame that surrounds each slide. A G Inc.

Your comfort level with your responses to the following 2 question assessment tool should indicate if the presentation that follows will increase you knowledge base on the topic outlined by the questions in this tool. Pre-presentation Self Assessment Activity

1) You have purchased “U-Betch-Um” model 123 pressure sensor. Its operational characteristics are as follows; Operation Recommendations Supply voltage10 Volts Current0.250 Ampere Strain gauge resistance 10 Ohms (+ or – 15%) Output voltage7.5 Volts (+ or – 15%) Draw the wiring diagram for this sensor and include values for all resistors. 2) If you have calibrated your “U-Betch-Um” model 123 pressure sensor to a steady state pressure value of 1 atmosphere, what will be the expected output voltage if the pressure is: (a) 1.15 atmospheres? (b) 1.40 atmospheres?

Pressure Sensor Strain gauge based sensor V strain R pull up V V out Operation Recommendations Supply voltage10 Volts Current0.250 Ampere Strain gauge resistance 10 Ohms (+ or – 15%) Output voltage7.5 Volts (+ or – 15%) “U-Betch-Um” model 123 pressure sensor “don’t call us, it worked before you opened this box.”

Pressure Sensor Strain gauge based sensor Strain gauge based pressure sensing device V strain V total R pull up V A strain gauge is a thin flexible membrane with a resistor embedded in the film. V out “U-Betch-Um” model 123 pressure sensor Function diagram

V strain V total R pull up V Strain gauge A strain gauge is a thin flexible membrane with a resistor embedded in the film. V pull up V strain + V total = V out V = When a strain gauge is flexed its resistance changes. Note: Pressure Sensor Strain gauge based sensor

V strain V total R pull up V Strain gauge A strain gauge is a thin flexible membrane with a resistor embedded in the film. V pull up V strain + V total = V out V = V total - V strain or When a strain gauge is flexed its resistance changes. Note: Pressure Sensor Strain gauge based sensor

V strain V total R pull up V Strain gauge A strain gauge is a thin flexible membrane with a resistor embedded in the film. V pull up V strain + V total = V out V = V total - V strain V out = or 0 Volts + V pull up When a strain gauge is flexed its resistance changes. Note: Pressure Sensor Strain gauge based sensor

Strain gauge V strain V total R pull up V strain equals the voltage drop across the strain gauge. V pull up V pull up equals the voltage drop across the pull up resistor, R pull up. V total equals the V strain plus V pull up. When a strain gauge is flexed its resistance changes. Note: V pull up V strain + V total = V out = V total - V strain or V out = 0 Volts + V pull up V out Pressure Sensor Strain gauge based sensor

Strain gauge V strain V total R pull up V strain equals the voltage drop across the strain gauge. V pull up V pull up equals the voltage drop across the pull up resistor, R pull up. V total equals the V strain plus V pull up. When a strain gauge is flexed its resistance changes. Note: V pull up V strain + V total = V out = V total - V strain or V out = 0 Volts + V pull up V out V strain V total R pull up V V out Pressure Sensor Strain gauge based sensor

V strain equals the voltage drop across the strain gauge. V pull up equals the voltage drop across the pull up resistor, R pull up. V total equals the V strain plus V pull up. When a strain gauge is flexed its resistance changes. Note: V out V strain V total R pull up V V out R pull up V V strain V total Strain gauge Pressure Sensor Strain gauge based sensor

V strain V total R pull up V V out V strain equals the voltage drop across the strain gauge. V pull up equals the voltage drop across the pull up resistor, R pull up. V total equals the V strain plus V pull up. When a strain gauge is flexed its resistance changes. Note: V strain V out V total Strain gauge R strainPressure Sensor Strain gauge based sensor R pull up V

V strain equals the voltage drop across the strain gauge. V pull up equals the voltage drop across the pull up resistor, R pull up. V total equals the V strain plus V pull up. When a strain gauge is flexed its resistance changes. Note: V strain V out V total R pull up V Strain gauge R strain Voltage value here; is the same value as V out is directly proportional to value of R strain. is “pulled up” from 0 volts by R pull up. Pressure Sensor Strain gauge based sensor

Post Presentation Self Assessment Activity 1) You have purchased “U-Betch-Um” model 123 pressure sensor. Its operational characteristics are as follows; Operation Recommendations Supply voltage10 Volts Current0.250 Ampere Strain gauge resistance 10 Ohms (+ or – 15%) Output voltage7.5 Volts (+ or – 15%) Draw the wiring diagram for this sensor and include values for all resistors. V out V total R pull up V R strain 30 Ohms R pull up = V = 7.5 volts V output = I total R pull up = V Pull up amps = 7.5 volts (+ or – 15%) 10 Volts 30 ohms 10 ohms (+ or – 15%) Sensor output voltage when pressure at steady state value

If you have calibrated your “U-Betch-Um” model 123 pressure sensor to a steady state pressure value of 1 atmosphere, what will be the expected output voltage if the pressure is: Post Presentation Self Assessment Activity 2) (a) 1.15 atmospheres? 7.5 volts (+ or – 15%) 10 Volts 30 ohms 10 ohms (+ or – 15%) 1.15 atmospheres (7.5 volts) (1 atmosphere) = 8.63 volts (b) 0 volts 1.4 atmospheres is more than 15% above the 1 atmosphere steady state pressure setting. the strain gauge in the sensor is not rated for this excess pressure. the strain gauge broke and output signal when to 0 volts atmospheres? Sensor output voltage when pressure at steady state value 0 Volts

End of Presentation A G Inc.