Lab 13 TF EIM

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DC Bipolar Transistor Curves

Data sheet for transistors.


2N3904 PinOuts.png2N3906 PinOuts.png

Using 2N3904 is more srtaight 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
Collector-Base breakdown voltage
Emitter-Base Breakdown Voltage
Maximum Collector Voltage
Maximum Collector Current
Transistor Power rating([math]P_{Max}[/math])
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 Lab13a Circuit.pngTF 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].

Find the resistors you need to have

[math]I_B = 2 \mu A[/math] , [math]5 \mu A[/math] , and [math]10 \mu A[/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_{BE}}{R_B}[/math]

V_{CC} V_B V_{BB} V_ {EC} V_ E R_E R_B I_E I_B
mV mV V mV mV [math]\Omega[/math] k[math]\Omega[/math] mA \muA

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

V_{CC} V_B V_{BB} V_ {EC} V_ E R_E R_B I_E I_B
mV mV V mV mV [math]\Omega[/math] k[math]\Omega[/math] mA \muA

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)


  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)

Extra credit

Measure the Base-Emmiter breakdown voltage. (10 pnts)

I expect to see a graph [math](I_{B} -vs- V_{BE} )[/math] and a linear fit which is similar to the forward biased diode curves. Compare your result to what is reported in the data sheet.