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: 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:
- Transistor Pinouts.jpg (150.78 KiB) Viewed 3270 times