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80 Cards in this Set

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  • Back
The term transistor
was derived from the words
TRANSfer and resISTOR.
which gives current carriers
EMITTER
which controls the flow of current carrier
BASE
which collects the current carriers
COLLECTOR
electron flow is always
toward or against the arrow, just like in the junction diode.
What was the name of the very first transistor?
Point-contact
To properly bias an NPN transistor, what polarity voltage is applied to the collector, and what is its
relationship to the base voltage?
Positive, more positive.
Why is conduction through the forward-biased junction of an NPN transistor primarily in one direction, namely from the emitter to base?
Because the N material on one side of the forward-biased junction is more heavily doped than the
P-material.
In the NPN transistor, what section is made very thin compared with the other two sections?
The P or base section.
What percentage of current in an NPN transistor reaches the collector?
98 percent.
What percentage of current in an NPN transistor reaches the Base?
2-5%
dc voltages and currents that exist in the circuit before the application of
a signal are known as?
QUIESCENT voltages and currents
used to pass the ac
input signal and block the dc voltage from the preceding circuit
coupling capacitor (CC)
In the basic transistor amplifier discussed earlier, what is the relationship between the polarity of the
input and output signals?
The signals are opposite in polarity or 180 degrees out of phase with each other.
Which biasing method is the most unstable?
Base-Current Bias (Fixed Bias)
What type of bias is used where only moderate changes in ambient temperature are expected?
Self-Bias
When is degeneration tolerable in an amplifier?
When it is necessary to prevent amplitude distortion
What is the most widely used combination-bias system?
voltage-divider
What amplifier class of operation allows collector current to flow during the complete cycle of the
input?
Class A
What is the name of the term used to describe the condition in a transistor when the emitter-base
junction has zero bias or is reverse biased and there is no collector current?
Cutoff
What two primary items determine the class of operation of an amplifier?
The amount of bias and the amplitude of the input signal.
What amplifier class of operation is the most inefficient but has the least distortion?
Class A.
used as an audio- and radio-frequency amplifier
Class A.
commonly used as a push-pull amplifier to overcome a side effect of class B operation called crossover distortion.
Class AB.
used extensively for audio amplifiers that require high-power outputs.
Class B
used as a radio-frequency amplifier in transmitters.
Class C
is the faithful reproduction of a signal
Fidelity
refers to the ratio of output-signal power compared to the total input
power
efficiency
H voltage Gain
L Current Gain
L Power Gain
L Input Resistance
H Output Resistance
In phase
Common Base
M voltage Gain
M Current Gain
H Power Gain
M Input Resistance
M Output Resistance
Out of phase
Common Emitter
L voltage Gain
H Current Gain
M Power Gain
H Input Resistance
L Output Resistance
In phase
Common Collector
Absolute Maximum Ratings of the transistor are
the direct voltage and current values that if exceeded in operation may result in transistor failure.
"2 N 130 A" Identify the marking of the tranistor.
2- NUMBER OF JUNCTIONS
N- SEMI-CONDUCTOR
130-IDENTIFICATION NUMBER
A-FIRST MODIFICATION
What is the greatest danger to a transistor?
heat
What method for checking transistors is cumbersome when more than one transistor is bad in a
circuit?
The substitution method
a colored dot, usually red, indicates the
collector
A basic transistor gain test can be made using
an ohmmeter and a
simple test circuit
When you are testing the gain of an audio-frequency transistor with an ohmmeter, what is indicated by a 10-to-1 resistance ratio?
Normal gain.
When you are using an ohmmeter to test a transistor for leakage, what is indicated by a low, but
not shorted, reverse resistance reading?
leakage
diode is a PN junction designed to operate in the reverse-bias breakdown region.
Zener
The voltage at which the
sudden increase in current occurs is called the?
BREAKDOWN VOLTAGE.
accounts for the breakdown below 5 volts; whereas, above 5 volts the breakdown is caused by the avalanche effect
Zener effect
band in which the energy level of the electrons is high enough that the electrons will move easily under the influence of an external field
CONDUCTION BAND
band in which the energy level is the same as the valence electrons of
the atoms
VALENCE BAND
electrons must cross a gap that exists between the valence band energy level and the conduction band
energy level
FORBIDDEN ENERGY BAND or FORBIDDEN GAP.
the semiconductor materials used in forming a junction are doped to the
extent of one-thousand impurity atoms for ten-million semiconductor atoms
TUNNEL DIODE
is a diode that behaves like a variable capacitor, with the PN junction functioning like the dielectric and plates of a common capacitor
Varactor
varactor, the width of the "gap" may be varied. An increase in reverse bias the what width of the gap (d) which what the capacitance (C) of the PN junction
increases
decreases
function as a switch that can turn on or off small or large amounts of power
Silicon controlled rectifier
When an SCR is forward biased, what is needed to cause it to conduct?
A gate signal
What is the only way to cause an SCR to stop conducting?
The forward bias must be reduced below the minimum conduction level.
controls and conducts current flow during both alternations of an ac cycle, instead of only one
TRIAC
The TRIAC is similar in operation to what device?
SCR.
When used for ac current control, during which alternation of the ac cycle does the TRIAC control
current flow?
During both alternations.
What type of bias is required to cause an LED to produce light?
Forward bias.
When compared to incandescent lamps, what is the power requirement of an LED?
Very low.
In a common anode, seven-segment LED display, an individual LED will light if a negative voltage is applied to what element?
The cathode
What is the resistance level of a photodiode in total darkness?
Very high
What type of bias is required for proper operation of a photodiode?
Reverse bias.
What is a typical light-to-dark resistance ratio for a photocell?
1:1000
What semiconductor device produces electrical energy when exposed to light?
Photovoltaic cell.
The UJT has how many PN junctions?
One.
The area between base 1 and base 2 in a UJT acts as what type of common circuit component?
Variable resistor.
The sequential rise in voltage between the two bases of the UJT is called what?
A voltage gradient.
What is the normal current path for a UJT?
From base 1 to the emitter
What is one of the primary advantages of the FET when compared to the bipolar transistor?
High input impedance.
The FET and the vacuum tube have what in common?
Voltage controls conduction.
The base of a transistor serves a purpose similar to what element of the FET?
Gate.
What are the two types of JFET?
N-channel and P-channel.
The source and drain of an N-channel JFET are made of what type of material?
N-type material.
What is the key to FET operation?
Effective cross-sectional area of the channel.
What is the normal current path in an N-channel JFET?
From source to drain.
Applying a reverse bias to the gate of an FET has what effect?
Source-to-drain resistance increases.
The input and output signals of a JFET amplifier have what phase relationship?
They are 180 degrees out of phase.
When compared to the JFET, what is the input impedance of the MOSFET?
The MOSFET has a higher input impedance.
What are the four elements of the MOSFET?
Gate, source, drain, and substrate.
The substrate of an N-channel MOSFET is made of what material?
P-type material.
In a MOSFET, which element is insulated from the channel material?
The gate terminal
What type of MOSFET can be independently controlled by two separate signals?
The dual-gate MOSFET.
What is the purpose of the spring or wire around the leads of a new MOSFET?
To prevent damage from static electricity.