quiz 1
Explain the difference between amplifier current gain and B (beta)
- amplifier current gain is for the whole circuit (I out / I in) - B (beta) is the gain of an individual transistor
what are three basic types of transistor (bjt) amplifier configurations?
- common collector - common emitter - common base
what are the 3 main types of amplifier coupling?
- transformer coupling - capacitor - direct
what is the forward voltage drop associated with germanium
0.2 V
what is the forward voltage drop associated with silicon.
0.6 V
what is phase inversion?
180 degree phase shift
what combined devices most closely resemble a triac?
2 reverse parallel SCRs
what is the voltage gain, Av, of an amplifying circuit if the input voltage is 12 mV and the output is 6 V.
500
what do the initials UJT stand for?
Unijunction transistor
why are base biased transistors used for switching circuits, not amplifier circuits?
a base biased circuit is B (beta) dependent and the gain can vary too much.
what is a multistage amplifier?
a series of amplifiers connected together to reach the desired output.
triacs and SCRs are
control devices
define output impedance.
effect on output objects
a transistor is in cutoff when it is conducting fully and the voltage across the collector emitter junction, Vce, is approximately 0V.
false
current gain, B (beta), is exactly the same for all transistors of a specific model
false
the base-emitter junction of a transistor must be reverse biased for operation in the linear region.
false
the current gain, Ai, for an amplifier circuit is always greater than the transistor current gain, B (beta).
false
what is another name for a common - emitter circuit?
ground - emitter circuit
where would a common - collector circuit be used?
high inoedance source to low impedance output.
in what region of the UJT characteristic curve does the UJT have it's greatest application?
in the negative resistance region
define input impedance
loading effect on incoming signal
what is impedance matching?
matching output impedance of amplifier to the input impedance of the load.
why is it best to have the operating point (Q point) of an amplifier circuit near the center of the load line?
maximum amplification without clipping or distortion.
why would a triac be used in an explosive environment?
no arc is created.
What is amplification?
producing gain
Define bandwidth.
range of frequency (Hz) at Max and gain of amplifier.
What is gain?
ratio of amplitude of output over input.
if the bypass capacitor in parallel with resistor Re in figure 1 was open what would happen to the ac gain of the amplifier?
the gain would decrease
what will happen if the voltage across a triac is too high?
the triac will turn on
what is the primary use for a diac?
triggering device
a bipolar juntion transistor is a current controlled - current source.
true
a change in the base current has a greater effect on collector current than does a change in collector voltage
true
a small change in base current of a base biased BJT will create a large change in the collector current
true
a transistor is in saturation when it is conducting fully and the voltage across the collector - emitter junction, Vce, is approximately 0V
true
current gain, B (beta), is equal to the collector current divided by the base current.
true
the base-collector junction of a transistor must be reverse biased for operation in the linear region.
true
define distortion.
undesirable change in signal
what is a decibel?
unit used to measure relative sound intensity.
what is the primary use for a UJT
used in triggering circuits to control other devices
what is a linear amplifier
when the output is exactly the same shape as the input signal, but amplified.
