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ABE 447SectionMonday 3:30-6pMarissa Lopez-Pier28.9.14

Task 1b: Regular Resistor as Temperature SensorTask 1bRT (C) 27R1 31600R2 992Vin 12.1Vout 0.38Vout-theor 0.368

BT(C) 37R1 20100R2 992Vin 12.1Vout 0.5

Vout-theor 0.569

y = 1.3711x - 0.021R = 1

05

10152025303540

0 5 10 15 20 25 30

V d r o p

( v o

l t s )

Temperature(C)

Voltage Drop vs. TemperatureThermistor

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Task 1b R1 R2 Vin Vout-theor Vdrop-exp %errorAmbient 768 760 12.1 6.018324607 6.04 0.003601566Finger 859 841 12.1 5.985941176 6 0.00234864

Calculations:

()

y = 0.6354x + 19.843R = 1

0

5000

10000

15000

20000

25000

0 5000 10000 15000 20000 25000 30000 35000

R e s

i s t a n c e

( o h m s

)

Temperature (C)

Resistance vs. TemperatureThermistor

y = 1.479x - 2.9332R = 1

05

10152025303540

0 5 10 15 20 25 30

V d r o p

( v o

l t s )

Temperature (C)

Voltage Drop vs. Temperature

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Discussion :For Task 1, the voltage drop was calculated theoretically using the voltage

divider method (as seen in calculations). The theoretical values were very close tothe measured values of V out. The thermistor demonstrated an inverserelationship, because when the resistance went down the temperature went up.This is seen at body temp 37 degrees Celsius resulting in a voltage drop of 0.5 Vinstead of 0.38 V at 27 degrees Celsius.

In Task 1b, the same trend is not seen because the voltage drops only varyby a 0.4 V voltage drop. This means the resistor can act like a thermistor, just withless sensitivity. This is because the resistor had only a 5% tolerance from 4 bands,

also the material of the resistor may have been overused. Thus the sensitivity is notenough to detect the temperature change and result in a significant voltage drop.

Task 2:Task2 Vb

I LM335(Vab) Vab Vb

I LM335(Vab) Vab

Ambient Ambient Finger Finger1 0.27 0.1 0.1 0.27 0.01 0.012 0.76 0.02 0.02 0.78 0.02 0.023 1.3 0.03 0.03 1.28 0.02 0.024 1.72 0.03 0.03 1.74 0.03 0.035 2.18 0.05 0.05 2.17 0.04 0.046 2.64 0.07 0.07 2.67 0.06 0.067 2.96 0.09 0.09 3.02 0.08 0.088 2.97 0.11 0.11 3.03 0.1 0.19 2.98 0.14 0.14 3.03 0.12 0.12

10 2.98 0.16 0.16 3.03 0.15 0.15

y = 1.1031x + 7.2157R = 1

0100200300400500600700800900

0 200 400 600 800 1000

R e s

i s t a n c e

( o h m

s )

Temperature (C)

Resistance vs. Temperature

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11 2.98 0.2 0.2 3.03 0.18 0.1812 2.98 0.23 0.23 3.03 0.21 0.2113 2.97 0.29 0.29 3.03 0.25 0.2514 2.98 0.35 0.35 3.03 0.32 0.3215 2.98 0.46 0.46 3.03 0.4 0.416 2.99 0.66 0.66 3.03 0.53 0.5317 2.99 1.14 1.14 3.03 0.82 0.8218 3 3.02 3.02 3.04 1.62 1.6219 4.57 6.32 6.32 3.05 6.48 6.4820 5.43 6.34 6.34 4.91 6.48 6.4821 5.46 6.34 6.34 5.36 6.48 6.48

0

1

2

3

4

5

6

0.1 0.02 0.03 0.03 0.05 0.07 0.09 0.11 0.14 0.16 0.2 0.23 0.29 0.35 0.46 0.66 1.14 3.02 6.32 6.34 6.34

V b ( v o

l t s )

I LM335 (Vab) (amps)

Vb vs. I LM335 (Vab) @ 27(C)

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Series 1 is room temperature, Series 2 is body temperature.

Discussion:In task 2 we used a Zener diode to measure the voltage drop of a diode at room

temperature and body temperature. The I LM335 vs. Vb curve was close to whatwhat is the text. The voltage across the thermistor remained constant from 0.5 mAto 10 mA, which is normal for the reverse bias of a Zener diode. It also had aconstant voltage from 2. 75 V to 3.4V. This was all conducted at room temperature,thus these results were what was expected. The body temperature results did notdetermine the trend suggested by the text, because the curve as you can seen in redon the graph is lower in voltage as the current increases through the diode. Thismeans that the temperature may have not affected the diode due to surroundingmaterial was plastic. Also the DMM and resistor may have affected the path of thecurrent.

0

1

2

3

4

5

6

0.01 0.02 0.02 0.03 0.04 0.06 0.08 0.1 0.12 0.15 0.18 0.21 0.25 0.32 0.4 0.53 0.82 1.62 6.48 6.48 6.48

V b ( v o

l t s )

I LM335 (amps)

Vb vs. IL335 (Vab) @37 (C)

6.34, 5.466.34, 5.36

0

1

2

3

4

5

6

V b f r o m

I L M 3 3 5 ( v o

l t s )

I LM335 (amps)

I LM335 vs. Vb from I LM335

Series1

Series2

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Problem 4.1:When there is a 5ma current, an LM335 thermistor, and a initial temperature

of 300K, there should not be a 3.10 V output voltage, but rather a 3.0 V output. Thisis because the text book demonstrates a similar study where a person with a bodytemperature of 298 K touched a thermistor LM335 with a 0.2-5mA current, and

observed a 2.98V. Also because body temperature( in K) and voltage output aredirectly related under a thermistor component. Also the 3.10 V could be caused byhigh current and self heating in the diode. When a finger or body temperature isapplied this would cause a voltage drop; 300K is 3.0V from 3.10V. Therefore contactwith the diode causes it to lose heat through conduction, which in turn lowersoutput voltage.

Task 3:

Task

3

I

set(LM334) Va Vc Vab

I set

(LM334) Va Vc Vab

AmbientAmbient

Ambient

Ambient Finger

Finger

Finger Finger

10.00030612

2 0.28 0.12 0.00030.00020408

2 0.08 0.130.000

2

20.00061224

5 0.83 0.52 0.00060.00051020

4 0.54 0.50.000

5

30.00081632

7 1.24 0.61 0.00080.00071428

6 1.08 0.610.000

7

4

0.00102040

8 1.35 0.63 0.001

0.00091836

7 1.31 0.62

0.000

9

50.00102040

8 1.4 0.63 0.0010.00102040

8 1.38 0.63 0.001

60.00102040

8 1.46 0.64 0.0010.00102040

8 1.43 0.64 0.001

70.00102040

8 1.6 0.64 0.0010.00102040

8 1.5 0.64 0.001

80.00102040

8 2.11 0.64 0.0010.00102040

8 1.84 0.64 0.001

90.00102040

8 2.57 0.64 0.0010.00102040

8 2.32 0.64 0.001

100.00102040

8 3.1 0.64 0.0010.00102040

8 2.86 0.64 0.001

110.00102040

8 3.67 0.64 0.0010.00102040

8 3.4 0.64 0.001

120.00102040

8 4.35 0.64 0.0010.00102040

8 4.05 0.64 0.00113 0.00102040 5.01 0.64 0.001 0.00102040 4.69 0.64 0.001

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8 8

140.00102040

8 5.72 0.64 0.0010.00102040

8 5.37 0.64 0.001

150.00102040

8 6.49 0.64 0.0010.00102040

8 6.1 0.64 0.001

160.00102040

8 7.32 0.64 0.0010.00102040

8 6.94 0.64 0.001

170.00102040

8 8.17 0.64 0.0010.00102040

8 7.77 0.64 0.001

180.00102040

8 9.13 0.64 0.0010.00102040

8 8.67 0.64 0.001

190.00102040

8 10.2 0.64 0.0010.00102040

8 9.67 0.64 0.001

200.00102040

8 11.17 0.64 0.0010.00102040

8 10.74 0.64 0.001

210.00102040

8 12.06 0.64 0.0010.00102040

8 11.72 0.64 0.001

220.00102040

8 12.12 0.64 0.0010.00102040

8 12.15 0.64 0.001

00.0000020.0000040.0000060.000008

0.000010.000012

0.0000140.0000160.000018

0 2 4 6 8 10 12 14

I s e t

f r o m

V a b

( a m p s )

Va (volts)

Va vs. I set Ambient (@27)

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Series 1 is at ambient temperature, Series 2 is at Body temperature.

00.0000020.0000040.0000060.000008

0.000010.0000120.000014

0.0000160.000018

0.00002

0 . 0

8

0 . 5

4

1 . 0

8

1 . 3

1

1 . 3

8

1 . 4

3 1

. 5

1 . 8

4

2 . 3

2

2 . 8

6 3

. 4

4 . 0

5

4 . 6

9

5 . 3

7 6

. 1

6 . 9

4

7 . 7

7

8 . 6

7

9 . 6

7

1 0

. 7 4

1 1

. 7 2

1 2

. 1 5

I s e t

f r o m

V a b

( a m p s )

Va (volts)

Va vs. I set BT (@37)

0

0.000002

0.000004

0.0000060.000008

0.00001

0.000012

0.000014

0.000016

0.000018

0.00002

0 2 4 6 8 10 12 14

I s e t

f r o m

V a b

( a m p s )

Va (volts)

Va vs. I set Ambient (@27)

Series1

Series2

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Problem 4.2 :The current Iset can be estimated with the resistor value of Rset= 1K ohm

() ( ) ( )

() ( )

()

0

0.1

0.2

0.3

0.40.5

0.6

0.7

0 2 4 6 8 10 12 14

V c

( v o

l t s )

Va (volts)

Va vs. Vc RT (@27)

00.1

0.2

0.3

0.4

0.5

0.6

0.7

0 2 4 6 8 10 12 14

V c

( v o

l t s

Va (volts)

Va vs. Vc BT(@37)

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It is assumed that the experiment is at room temperature. Thus VR=67.7mV.

()

The current I set is stated in the lab manual that it is conserved, thus the V transistorcan be determined from I set.

Discussion :In Task 3 a bypass circuit was constructed with a 68 ohms resistor , and

tested at body and room (ambient) temperature. The 68 ohms circuit in thisexperiment is suppose to have a voltage that correlates to the ambient or bodytemperature it cones in contact with. For our circuit there was a 1mA current, andwe observed several voltage inputs. The current was normal , and the resistance of

the 1 Ohm resistor was a little lower at 0.98 ohms. The transistor still did its jobthough and leveled off the voltages for the thermistor (LM334). The transistor actedlike a temperature sensor, because when the temperature sensor ( transistor) cameinto contact with my hands it compensated for the change in temperature and thevoltage increased. You can see this in the series two of the combined graphs. It isslightly higher than ambient. Since this increase was seen there is also an increasein VR.