TF EIMLab13 Writeup

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DC Bipolar Transistor Curves

Data sheet for transistors.

Media:2N3904.pdfMedia:2N3906.pdf

2N3904 PinOuts.png2N3906 PinOuts.png


Using 2N3904 is more straight forward in this lab.

Transistor circuit

1.) Identify the type (n-p-n or p-n-p) of transistor you are using and fill in the following specifications.


Value Description
40 V Collector-Base breakdown voltage
6 V Emitter-Base Breakdown Voltage
40 Maximum Collector Voltage
200 mA Maximum Collector Current
625 mW Transistor Power rating([math]P_{Max}[/math])
30 - 300 DC current gain [math]h_{FE}( I_C, V_{CE})[/math]


2.) Construct the circuit below according to the type of transistor you have.

TF EIM Lab13 Circuit.png


Let [math]R_E = 100 \Omega[/math].

[math]V_{CC} \lt 5 Volts[/math] variable power supply

[math]V_{BE}= 1V[/math].

I_B = 2[math] \mu[/math] A = 1V/500 k[math] \Omega[/math]

= 5[math] \mu[/math] A = 1V/200 k [math]\Omega[/math]
= 10 [math]\mu A[/math] = 1V/100 k [math]\Omega[/math]

3.) Measure the emitter current [math]I_E[/math] for several values of [math]V_{CE}[/math] by changing [math]V_{CC}[/math] such that the base current [math]I_B = 2 \mu[/math] A is constant. [math]I_B \approx \frac{V_{BB}-V_{b}}{R_B}[/math]

[math]R_{B} = 500 k \Omega[/math]

[math]R_{E} = 101 \Omega[/math]


[math]V_{BB} -V_B[/math] [math]I_B[/math] [math]V_{CC}[/math] [math] V_ E[/math] [math]I_E[/math]
V [math]\mu[/math] A V mV mA
1.007 2 0.0704 1.2
1.05 2 0.110 4.9
1.02 2 0.133 8.9
1.002 2 0.162 15.7
1.002 2 0.184 21.1
1.026 2 0.2287 32.3
1.012 2 0.3157 39.5
1.008 2 0.484 40.0
1.008 2 1.023 40.3
1.008 2 2.167 40.7
1.008 2 2.960 40.8
1.008 2 5.00 41.2


4.) Repeat the previous measurements for [math]I_B \approx 5 \mbox{ and } 10 \mu[/math] A. Remember to keep [math]I_CV_{CE} \lt P_{max}[/math] so the transistor doesn't burn out

[math]R_{B} = 201.8 k \Omega[/math]

[math]V_{BB} -V_B[/math] [math]I_B[/math] [math]V_{CC}[/math] [math] V_ E[/math] [math]I_E[/math]
V [math]\mu[/math] A V mV mA
1.044 5 0.094 7
1.053 5 0.134 19
1.026 5 0.167 32
1.003 5 0.200 47
1.003 5 0.234 62
1.02 5 0.269 77
1.0 5 0.289 83
1.07 5 0.442 101
1.02 5 0.721 99
1.02 5 1.04 100
1.02 5 1.94 100
1.02 5 2.96 101
1.02 5 3.72 102

[math]R_{B} = 100 k \Omega[/math]


[math]V_{BB} -V_B[/math] [math]I_B[/math] [math]V_{CC}[/math] [math] V_ E[/math] [math]I_E[/math]
V [math]\mu[/math] A V mV mA
0.942 10 0.227 78.1
1.005 10 0.245 94
0.995 10 0.267 108
1.068 10 0.31 138
1.005 10 0.355 160
0.996 10 1.032 197
1.002 10 0.688 197
0.996 10 2.175 199
0.994 10 3.283 200
0.992 10 4.66 202


5.) Graph [math]I_C[/math] -vs- [math]V_{CE}[/math] for each value of [math]I_B[/math] and [math]V_{CC}[/math] above. (40 pnts)

6.) Overlay points from the transistor's data sheet on the graph in part 5.).(10 pnts)

Questions

  1. Compare your measured value of [math]h_{FE}[/math] or [math]\beta[/math] for the transistor to the spec sheet? (10 pnts)
  2. What is [math]\alpha[/math] for the transistor?(10 pnts)
  3. The base must always be more _________(________) than the emitter for a npn (pnp)transistor to conduct I_C.(10 pnts)
  4. For a transistor to conduct I_C the base-emitter junction must be ___________ biased.(10 pnts)
  5. For a transistor to conduct I_C the collector-base junction must be ___________ biased.(10 pnts)


Forest_Electronic_Instrumentation_and_Measurement