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151 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Electron tubes are classified according to |
the number of electrodes they contain |
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What are the 2 electrodes in a diode? |
Cathode and plate |
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In a diode tube, what are the 2 electrodes? |
Plate (anode) which receives the electrons. Cathode which emits the electrons |
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Current flows in a diode tube from |
Cathode to plate (negative to positive) |
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What is thermal emission? |
The discharge of electrons from a material when the material is subjected to high temps (As the applied temp increases, the # of free electrons increases) |
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Cathode is made of what material? |
Tungsten that is coated with thorium oxide. |
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What are the 2 types of heater filaments? |
Directly heated cathode Indirectly heated cathode |
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Indirectly heated cathode |
A twisted or folded loop of insulated tungsten wire which is inserted into a thin walled hollow metal cylinder |
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2 major disadvantages of directly heated |
With DC heater voltages, potential in the wire is not consistent (making emission of electrons inconsistent)
With AC heater voltages, undesirable variations in emission current (hum) may occur. |
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Electron tubes envelopes are |
Gas filled and drawn to a vacuum. |
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What is the envelope in a diode tube made of? |
Glass or ceramic material |
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How many electrodes does a triode have? |
3 |
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What electrode is added in a triode? |
Control grid |
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What is the purpose of a control grid? |
Regulate the amount of electron flow between the cathode and plate |
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What does the control grid control? |
The resistance of the tube |
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How many electrodes in the tetrode? |
4 |
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What is the electrode added to a tetrode? |
Screen grid |
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How many electrodes are in a pentode? |
5 |
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What electrode is added to a pentode? |
Suppressor grid |
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What is a gas filled tube? |
Has an inert has injected into it after the air has been removed.
(When voltage is first applied, the gas opposes current) |
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What is a voltage regulator tube? |
As current goes up, resistance of the tube goes down producing a voltage drop |
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What is the major disadvantage of a triode? |
Interelectrode capacitance due to the wide surface areas of the plate and control grid |
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What component replaced the triode as an amplifier during the solid state revolution? |
Transistor |
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What does the screen grid do to the tetrode? |
Reduces the amount of interelectrode capacitance |
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What does the screen grid do to the tetrode? |
Reduces the amount of interelectrode capacitance |
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What is the major disadvantage of a tetrode? |
Removed by the addition of the fifth electrode in the pentode |
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What does the screen grid do to the tetrode? |
Reduces the amount of interelectrode capacitance |
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What is the major disadvantage of a tetrode? |
Removed by the addition of the fifth electrode in the pentode |
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Where is the screen grid located? |
Between the plate and control grid |
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What does the screen grid do to the tetrode? |
Reduces the amount of interelectrode capacitance |
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What is the major disadvantage of a tetrode? |
Removed by the addition of the fifth electrode in the pentode |
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Where is the screen grid located? |
Between the plate and control grid |
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What does the suppressor grid do in the pentode? |
Reduces the secondary emission from the plate |
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What does the screen grid do to the tetrode? |
Reduces the amount of interelectrode capacitance |
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What is the major disadvantage of a tetrode? |
Removed by the addition of the fifth electrode in the pentode |
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Where is the screen grid located? |
Between the plate and control grid |
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What does the suppressor grid do in the pentode? |
Reduces the secondary emission from the plate |
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What is secondary emission? |
The velocity of electrons in electron tubes (as they hit the plate was knocking off other electrons) |
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How many advantages does the suppressor grid provide to electron tube operation? |
2 |
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What is the most common electron tube application? |
Amplifier operation |
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What are the 3 electron tube amplifier configurations? |
Common cathode Common plate Common grid |
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How can amplifier configuration be identified? |
By determining the electrode to which the input signal is applied and the electrode from which the output is taken |
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What is a common cathode amplifier? |
Input is applied to control grid with respect to ground. Output is taken from the plate with respect to the ground. |
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What is cathode current (Ik)? |
Current that flows in the cathode lead |
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What is cathode current (Ik)? |
Current that flows in the cathode lead |
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What is plate current (Ip)? |
Current that flows in the plate |
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What is cathode current (Ik)? |
Current that flows in the cathode lead |
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What is plate current (Ip)? |
Current that flows in the plate |
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What is static current? |
No input signal is applied |
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Positive input for common cathode amplifier |
Bias decreases, R of V1 decreases. Plate current increases, voltage across R1 increases. Voltage across tube decreases. |
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Negative input for common cathode amplifier |
Bias increases, R of V1 increases. Current through plate load resistor decreases, voltage across V1 increases. |
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What is the output of a common cathode? |
180 degrees out of phase with input signalehat is a |
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What is a common plate (cathode follower amplifier)? |
Normally used for impedance matching. Input is applied to grid and output is taken from cathode. |
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What is the output of a common cathode? |
180 degrees out of phase with input signalehat is a |
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What is a common plate (cathode follower amplifier)? |
Normally used for impedance matching. Input is applied to grid and output is taken from cathode. |
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Positive input of common plate |
Bias decreases, R of V1 decreases. Current increases, Vr2 (load/bias resistor) increases. |
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What is the output of a common cathode? |
180 degrees out of phase with input signalehat is a |
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What is a common plate (cathode follower amplifier)? |
Normally used for impedance matching. Input is applied to grid and output is taken from cathode. |
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Positive input of common plate |
Bias decreases, R of V1 decreases. Current increases, Vr2 (load/bias resistor) increases. |
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Negative input of common plate |
Bias increases, R of V1 decreases. Current decreases, Vr2 decreases. |
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What is a cathode follower (common plate) commonly used for? |
Impedance marching |
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What causes the output of a common plate (cathode follower) to ALWAYS be less than the input? |
Degeneration |
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What is a common grid (grounded grid amplifier)? |
Input is applied to the cathode and the output is taken from the plate |
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What is a common grid (grounded grid amplifier)? |
Input is applied to the cathode and the output is taken from the plate |
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Positive input of common grid configuration |
Bias increases, R of tube decreases, current decreases. Vr1 increases and output increases |
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What is a common grid (grounded grid amplifier)? |
Input is applied to the cathode and the output is taken from the plate |
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Positive input of common grid configuration |
Bias increases, R of tube decreases, current decreases. Vr1 increases and output increases |
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Negative input of common grid configuration |
Bias decreases, R of tube decreases, current increases. Vr1 increases and output decreases. |
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What is the main disadvantage of a common grid configuration? |
Input source must furnish an appreciable amount of power to amplifier |
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What is a cathode ray tube (CRT)? |
A special type of electron tube that converts electrical signals into a visible image |
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What are the 2 basic types of CRTs? |
Electrostatic Electromagnetic |
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What is an electrostatic type CRT? |
Deflection of the beam is accomplished electrostatically by means of deflecting electrodes within the envelope |
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What is an electrostatic type CRT? |
Deflection of the beam is accomplished electrostatically by means of deflecting electrodes within the envelope |
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What are electromagnetic types in CRT? |
Use deflecting coils placed on the neck of the CRT |
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What is an electrostatic type CRT? |
Deflection of the beam is accomplished electrostatically by means of deflecting electrodes within the envelope |
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What are electromagnetic types in CRT? |
Use deflecting coils placed on the neck of the CRT |
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What is an electron gun? |
Introduces, accelerates, and focuses free electrons into a narrow beam |
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What is an electrostatic type CRT? |
Deflection of the beam is accomplished electrostatically by means of deflecting electrodes within the envelope |
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What are electromagnetic types in CRT? |
Use deflecting coils placed on the neck of the CRT |
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What is an electron gun? |
Introduces, accelerates, and focuses free electrons into a narrow beam |
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What are the essential parts of the electron gun? |
Cathode, control grid, focusing anode, accelerating anode |
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How many colors does the screen produce? |
One! (Monochrome) |
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How many colors does the screen produce? |
One! (Monochrome) |
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Aquadag coating returns the secondary electrons to the |
Power supply |
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Electromagnetic CRT causes deflections how? |
Vertical magnetic field cause horizontal deflection. Horizontal magnetic field causes vertical deflection. |
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CRT schematic symbols |
Back (Definition) |
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What type of device is a transistor? |
Solid state device (operates by the movement of electrons within a semiconductor material) |
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What are the transistors 3 terminal devices? |
Amplifiers Oscillators Electronic switches |
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What is an amplifier? |
Increase power. |
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What is an amplifier? |
Increase power. |
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What is an oscillator? |
A circuit that provides an AC signal |
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What is an amplifier? |
Increase power. |
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What is an oscillator? |
A circuit that provides an AC signal |
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What is an electronic switch? |
A circuit that controls the directions of current flow |
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What is the purpose of a transistor? |
Control current! Small current controls a large current |
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What is an amplifier? |
Increase power. |
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What is an oscillator? |
A circuit that provides an AC signal |
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What is an electronic switch? |
A circuit that controls the directions of current flow |
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What is the purpose of a transistor? |
Control current! Small current controls a large current |
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What is an amplifier? |
Increase power. |
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What is an oscillator? |
A circuit that provides an AC signal |
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What is an electronic switch? |
A circuit that controls the directions of current flow |
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What is the purpose of a transistor? |
Control current! Small current controls a large current |
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Transistor is derive from... |
TRANSfer and resISTOR |
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How does a transistor transfer internal resistance? |
From a low resistance (LowR) between emitter and base terminals, to a higher resistance (HighR) between the collector and base terminals |
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A low R between the emitter and base are what bias? |
Forward |
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A high R that is between collector and base is what bias? |
Reversed |
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A high R that is between collector and base is what bias? |
Reversed |
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How many elements does a transistor have? |
3 elements with 2 PN junctions |
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What is the emitter? |
Heavily doped element that transmits a large amount of current carriers (holes and electrons) |
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What is the base of a transistor? |
Very lightly doped element that allows most current carriers to pass from emitter to collector |
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What is the base of a transistor? |
Very lightly doped element that allows most current carriers to pass from emitter to collector |
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What is a collector? |
Moderately doped element that collects current from the base |
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What is the base of a transistor? |
Very lightly doped element that allows most current carriers to pass from emitter to collector |
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What is a collector? |
Moderately doped element that collects current from the base |
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An NPN transistor has arrow... |
Not Pointing In |
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A PNP has arrow... |
Pointing In |
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What is the reference designation for a transistor? |
Q |
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What is the reference designation for a transistor? |
Q |
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What are the 2 types is signals applied to transistors? |
Input (AC or DC) Bias (DC) |
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What is the reference designation for a transistor? |
Q |
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What are the 2 types is signals applied to transistors? |
Input (AC or DC) Bias (DC) |
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Transistor must be biased with what before use? |
DC voltages |
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What is the reference designation for a transistor? |
Q |
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What are the 2 types is signals applied to transistors? |
Input (AC or DC) Bias (DC) |
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Transistor must be biased with what before use? |
DC voltages |
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Current cannot flow what way in a transistor junction? |
From collector to base |
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Formula for total emitter current |
Ie = Ib + Ic |
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Proper Operating NPN transitor |
Eb diode is forward biased and Cb is reverse biased. |
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Proper operating PNP transistor |
Eb diode is forward biased and Cb is reverse biased |
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In an NPN transistor, the bias DC voltage must be |
Positive compared to the emitter |
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In a PNP transistor, the bias DC voltage must be |
Negative compared to the emitter |
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How many bolts are needed to forward bias the junction? |
.7 volts |
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Increasing base bias does what to collector current? |
Increases |
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Decreasing base bias does what to collector current |
Decreases |
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What is saturation? |
The point where an increase in base voltage does not increase collector current |
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What is cutoff? |
The point where the base bias reverse biases the EB junction, stopping Ib and Ic current flow |
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What happens in a transistor when the saturation point is reached? |
Ic stops flowing |
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What happens in a transistor when the saturation point is reached? |
Ic stops flowing |
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What happens in a transistor when the base voltage reverse biases the emitter to base PN junction? |
Cut off occurs |
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What are the 2 ratios for a transistor? |
Alpha and Beta |
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What are the 2 ratios for a transistor? |
Alpha and Beta |
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What is alpha? |
The ratio of collector current (Ic) to the emitter current (Ie) |
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Formula for alpha |
a = Ic/Ie |
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Alpha will never exceed what? |
1. (Normal range is .97 and .99) |
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Alpha will never exceed what? |
1. (Normal range is .97 and .99) |
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What is beta? |
The ratio of collector current (Ic) to base current (Ib) |
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Formula for beta |
B = Ic/Ib |
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What is the normal beta value? |
Normal beta value is between 20 and 400. |
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What are he 3 types of basic bias circuits? |
Fixed Self Combination |
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What are he 3 types of basic bias circuits? |
Fixed Self Combination |
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