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[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
	10

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