TF EIMLab13 Writeup

DC Bipolar Transistor Curves

Data sheet for transistors.

Media:2N3904.pdfMedia:2N3906.pdf

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($P_{Max}$)
	DC current gain $h_{FE}( I_C, V_{CE})$

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

Let $R_E = 100 \Omega$.

$V_{CC} \lt 5 Volts$ variable power supply

$V_{BE}= 1V$.

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

= 5 \mu A = 1V/200 k \Omega

= 10 \mu A = 1V/100 k \Omega

3.) Measure the emitter current $I_E$ for several values of $V_{CE}$ by changing $V_{CC}$ such that the base current $I_B = 2 \mu$ A is constant. $I_B \approx \frac{V_{bb}-V_{BE}}{R_B}$

V_{CC}	V_B	V_{BB}	V_ E	R_E	R_B	I_E	I_B
mV	mV	V	mV	\Omega	k\Omega	mA	\muA
0.1	0.6			101	490

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

V_{CC}	V_B	V_{BB}	V_ E	R_E	R_B	I_E	I_B
mV	mV	V	mV	\Omega	k\Omega	mA	\muA
0.1	0.6			101	290
0.1	0.6			101	100

5.) Graph $I_C$ -vs- $V_{CE}$ for each value of $I_B$ and $V_{CC}$ 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 $h_{FE}$ or $\beta$ for the transistor to the spec sheet? (10 pnts)
2. What is $\alpha$ 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