Lab 13 RS

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DC Bipolar Transistor Curves

Data sheet for transistors.

Media:2N3904.pdfMedia:2N3906.pdf

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
$V_{(BR)CEO} = 40\ V$	Collector-Base breakdown voltage
$V_{(BR)EBO} = 6\ V$	Emitter-Base Breakdown Voltage
$V_{(BR)CEO} = 40\ V$	Maximum Collector-Emitter Voltage
$V_{(BR)CBO} = 60\ V$	Maximum Collector-Emitter Voltage
$I_C = 200\ mA$	Maximum Collector Current - Continuous
$625\ mW$	Transistor Power rating($P_{Max}$)
$h_{FE} =$	DC current gain $h_{FE}( I_C, V_{CE})$
$h_{FE} = 40$ $h_{FE} = 70$ $h_{FE} = 100$	$I_C = 0.1\ mA$, $V_{CE} = 1.0\ V$

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

$V_{BE}= 1V$.

Find the resistors you need to have

$I_B = 2 \mu A$ , $5 \mu A$ , and $10 \mu A$

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_ {EC}	V_ E	R_E	R_B	I_E	I_B
mV	mV	V	mV	mV	$\Omega$	k$\Omega$	mA	\muA

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_ {EC}	V_ E	R_E	R_B	I_E	I_B
mV	mV	V	mV	mV	$\Omega$	k$\Omega$	mA	\muA

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)

Extra credit

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

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

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