Week #7: (10/14-18) Transistor Biasing

rjagodowski
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Joined: Fri Sep 04, 2015 6:59 pm

Week #7: (10/14-18) Transistor Biasing

This week's lab will be Experiment #5 handouts on Transistor Bias Circuits. A copy will be provided for you. A pdf of this lab can be found in the Registered Users Only area here. You must be registered and logged in to view content in this area.)

You may find this link to Transistor Biasing from Electronics-Tutorials.ws handy.

When you complete this exercise, create a progress report post as a Reply to this Topic.

You will perform the calculations, build and test the four circuits in Part 1 of the lab sheets. We will not discuss the circuits in Part 2 until a bit later in the course.
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Part 1: Build & verify all 4 circuits. You may substitute a 2N2222 for the 2N3904. Suggestion: Use your multi-meter to check each transistor BEFORE putting it in the circuit. Here is a pdf of the procedure:
Transistor DMM Check.pdf
You will make the measurements for each of 3 transistors for each circuit. This will help demonstrate the stability of the Q-point with respect to transistor variations.

Here are the formulas required for each circuit:

Fig. 5-1:
VRB=VCC-0.7V
IB=(VCC-0.7V)/RB
IC=(beta)*IB (assume beta around 150-200)
VRC=IC * RC
VC=12V-VRC
VCE=VC-VE=VC-0=VC

Fig. 5-2:
IB=(VCC-0.7)/(RB+beta*RE)
VRB=IB*RB
IC=beta*IB
VRC=IC*RC
VC=VCC-VRC
VCE=VC-VE=VC-VRE where VRE=IC*RE

Fig. 5-3:
VB=VCC(R2/(R1+R2))
VE=VB-0.7
IE=IC=(VE-0)/RE
VRC=IC*RC
VC=VCC-VRC
VCE=VC-VE

Fig. 5-4:
VB=0.7
IE=IC= (VCC-VBE)/(RB/beta+RC)=(VCC-0.7)/(RB/beta+RC)
VRC=IC*RC
VC=VCC-VRC

And here's a pdf of the above forumulas and the Transistor Pinout shown below:
Biasing Formulas v18.1.pdf 