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([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.

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 \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 [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_ E	R_E	R_B	I_E	I_B
mV	mV	mV	mV	\Omega	k\Omega	mA	\muA
0.120	853/2	913/2		101	92.7

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_ 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 [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