OBJECTIVE A: Identify a two-stage direct coupled amplifier circuit and measure the dc operatingvoltages.1. D. Measure and record the dc voltages (with respect to ground) at the base, emitter, andcollector of Q1.VB1 = 0.728 VdcVE1 = 145.4 mVdcVC1 = 22.2 VdcE. As a result of your measurements, would you say that the first common-emitterstage of the direct coupled amplifier is forward biased? YESF. M
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OBJECTIVE A: Identify a two-stage direct coupled amplifier circuit and measure the dc operating
voltages.
1. D. Measure and record the dc voltages (with respect to ground) at the base, emitter, and
collector of Q1.
VB1 = 0.728 Vdc
VE1 = 145.4 mVdc
VC1 = 22.2 Vdc
E. As a result of your measurements, would you say that the first common-emitter
stage of the direct coupled amplifier is forward biased? YES
F. Measure and record the dc voltages the base, emitter and collector of Q2.
VB2 = 22.54 Vdc
VE2 = 23.2 Vdc
VC2 = 6.92 Vdc
G. Is the second common-emitter amplifier stage properly biased? YES
OBJECTIVE B: Demonstrate the operation and measure the ac voltage gains of a typical direct
coupled amplifier, with and without emitter by-passing.
2. D. Connect the input of the oscilloscope to the base of Q1 and measure the peak-to-peak
input voltage.
eI = 0.1 V pk-pk
F. Is the output waveform at the collector a true amplified reproduction of the input
waveform? YES
G. Measure the peak-to-peak output voltage at the collector of Q1.
eC1 = 0.7 V pk-pk
H. Calculate the voltage gain of the first transformer coupled stage.
AV1=7
J. Is the output waveform of the second stage a true amplified reproduction of the input
waveform? YES
K. Measure the peak-to-peak output voltage of the direct coupled amplifier.
eo = 6.4 V pk-pk
L. Calculate the voltage gain Av of the second common-emitter stage.
AV2=9
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