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Pressure Sensors are always pushed around
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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
Pre-presentation Self Assessment Activity
1) You have purchased “U-Betch-Um” model 123 pressure sensor. Its operational characteristics are as follows; Operation
RecommendationsSupply voltage 10 Volts
Current 0.250 Ampere
Strain gauge resistance
10 Ohms (+ or – 15%)
Output voltage
7.5 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
Vstrain
Rpull up
Vpull up
Vout
Operation RecommendationsSupply voltage 10 Volts
Current 0.250 Ampere
Strain gauge resistance
10 Ohms (+ or – 15%)
Output voltage
7.5 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 gaugebased pressure sensing device
Vstrain
Vtotal
Rpull up
Vpull up
A strain gauge is a thin flexible membrane with a resistor embedded in the film.
Vout
“U-Betch-Um” model 123 pressure sensor
Function diagram
Vstrain
Vtotal
Rpull up
Vpull up
Strain gauge
A strain gauge is a thin flexible membrane with a resistor embedded in the film.
Vpull up
Vstrain
+Vtotal=
Vout
Vout=
When a strain gauge is flexed its resistance changes.
Note:
Pressure Sensor Strain gauge based sensor
Vstrain
Vtotal
Rpull up
Vpull up
Strain gauge
A strain gauge is a thin flexible membrane with a resistor embedded in the film.
Vpull up
Vstrain
+Vtotal=
Vout
Vout= Vtotal- V
straino
r
When a strain gauge is flexed its resistance changes.
Note:
Pressure Sensor Strain gauge based sensor
Vstrain
Vtotal
Rpull up
Vpull up
Strain gauge
A strain gauge is a thin flexible membrane with a resistor embedded in the film.
Vpull up
Vstrain
+Vtotal=
Vout
Vout= Vtotal- V
strain
Vout=or 0 Volts
+
Vpull up
When a strain gauge is flexed its resistance changes.
Note:
Pressure Sensor Strain gauge based sensor
Strain gauge
Vstrain
Vtotal
Rpull up
Vstrain equals the voltage drop across the strain gauge.
Vpull up
Vpull up equals the voltage drop across the pull up resistor, R pull up. Vtotal equals the Vstrain plus V pull
up.
When a strain gauge is flexed its resistance changes.
Note:
Vpull up
Vstrain
+Vtotal=
Vout= Vtotal- V
straino
r Vout= 0 Volts +
Vpull up
Vout
Pressure Sensor Strain gauge based sensor
Strain gauge
Vstrain
Vtotal
Rpull up
Vstrain equals the voltage drop across the strain gauge.
Vpull up
Vpull up equals the voltage drop across the pull up resistor, R pull up. Vtotal equals the Vstrain plus V pull
up.
When a strain gauge is flexed its resistance changes.
Note:
Vpull up
Vstrain
+Vtotal=
Vout= Vtotal- V
straino
r Vout= 0 Volts +
Vpull up
Vout
Vstrain
Vtotal
Rpull up
Vpull up
Vout
Pressure Sensor Strain gauge based sensor
Vstrain equals the voltage drop across the strain gauge. Vpull up equals the voltage drop across the pull up resistor, R pull up. Vtotal equals the Vstrain plus V pull
up.
When a strain gauge is flexed its resistance changes.
Note:
Vout
Vstrain
Vtotal
Rpull up
Vpull up
Vout
Rpull up
Vpull up
Vstrain
Vtotal
Strain gauge
Pressure Sensor Strain gauge based sensor
Vstrain
Vtotal
Rpull up
Vpull up
Vout
Vstrain equals the voltage drop across the strain gauge. Vpull up equals the voltage drop across the pull up resistor, R pull up. Vtotal equals the Vstrain plus V pull
up.
When a strain gauge is flexed its resistance changes.
Note:
Vstrain
Vout
Vtotal
Strain gauge
Rstrain
Pressure Sensor Strain gauge based sensor
Rpull up
Vpull up
Vstrain equals the voltage drop across the strain gauge. Vpull up equals the voltage drop across the pull up resistor, R pull up. Vtotal equals the Vstrain plus V pull
up.
When a strain gauge is flexed its resistance changes.
Note:
Vstrain
Vout
Vtotal
Rpull up
Vpull up
Strain gauge
Rstrain Voltage value here;
is the same value as Vout
is directly proportional to value of Rstrain.
is “pulled up” from 0 volts by Rpull 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
RecommendationsSupply voltage 10 Volts
Current 0.250 Ampere
Strain gauge resistance
10 Ohms (+ or – 15%)
Output voltage
7.5 Volts (+ or – 15%)
Draw the wiring diagram for this sensor and include values for all resistors.
Vout
Vtotal
Rpull up
Vpull up
Rstrain
30 Ohms
Rpull up=
Vpull up
=7.5 volts
Voutput
=
I totalRpull up
=VPull
up 0.250 amps=
7.5 volts
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.
1.40 atmospheres?
Sensor output voltage when pressure at steady state value
0 Volts
End of Presentation
A G
Inc.
