This week's lab will be Experiment #5 handouts on Transistor Bias Circuits. 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, then build them in EWB or Circuit Maker and compare the results to your measurements and calculations. The circuits in Part 2 you will build only in EWB or Circuit Maker.
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. Sample EWB files are included below for your convenience. You can change the value of beta used in the WEB IDEAL transistor model by right-clicking on the transistor, select properties and then adjust the Forward Current Gain parameter to the value of beta.
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
Part 2: Do not build these circuits. Verify these circuits using Electronics Workbench only. You have to create these circuits on your own. Be sure to save the EWB file for each circuit you create.
Here's a picture of the pinouts for common small-signal transistors:
Week #8: (10/26-30) Transistor Biasing
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Week #8: (10/26-30) Transistor Biasing
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- transistorlab_fig_5.1.ewb
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- transistorlab_fig_5.2.ewb
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Re: Week #8: (10/26-30) Transistor Biasing
Lab Week#8:Transistor Biasing is complete.