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| What is the purpose of a diode? |
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Definition
| To conduct current freely in one direction and oppose current flow in opposite direction. This is done by applying voltage across PN junction called Bias. |
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The process of adding impurities to the crystal structure is referred to as ______________. |
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Majority current carriers are produced through the process of doping. |
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Minority current carriers are produced by applying energy (heat, light, etc.) to the semiconductor. |
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In N-type material, the majority current carriers are the __________. |
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Junction recombination results in the development of a ___________ region or junction barrier. |
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Connecting the positive side of the battery to the P-material of a diode and the negative side to the N-material will establish ________ bias.
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1. Increasing the amount of forward bias will _______ the current through a PN junction diode. |
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Definition
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1. Thermal runaway is the result of excessive (forward or reverse) bias of a diode. |
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Definition
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1. All semiconductor materials have a negative temperature coefficient of resistance meaning that as the temperature of a diode increases its resistance _______. |
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Definition
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| What is junction recombination? |
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Definition
| The reduction of the # of free electrons and holes near the junction. The loss of an electron from the atoms in the N-type Material creates a Positive ion while the loss of a hole from the P-type material creates a negative ion. |
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| The electrostatic field in a junction due to junction recomnination similar to a charge across a capacitor is called? |
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Definition
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| Since the junction is void of all current carriers this is known as? |
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Definition
| Depletion Region or Junction Barrier |
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| The anode always points to? |
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Definition
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Term
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Definition
| The application of a voltage potential across a PN Junction. |
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| What are the two types of Bias? |
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Definition
| Foward Bias and Reverse Bias |
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| In foward bias the width of the barrier junction depletion decreases current does what? |
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Definition
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| Zero ohms are measured across a diode in both directions..the diode is? |
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Definition
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1. If infinity is measured with an ohmmeter across a diode in both directions, the diode is _____. |
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Definition
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1. When checking a diode with the diode checker function of a digital multimeter, a continuous tone in both directions indicates a ______ diode. |
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Definition
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| In order for a diode to be good, the resistance must be 10 times or more greater than the? |
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Definition
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When checking the resistance in a diode for resistance from foward bias the diode checker should ?
red lead on anode..black lead on cathode. |
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Definition
| Beep..indicating a low resistance. |
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| In a resitance check for a diode what are the 3 possible faults? |
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Definition
Short- 0 ohms in both directions
Open- infinite ohms in both directions
leaky- low resistance when reverse bias |
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| Resistance checks in the revers bias setting should red lead to cathode and black lead to anode there should be? |
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Definition
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| High resistance diode will give you a? |
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Definition
| Continuous tone in both directions. |
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| Semiconductor devices that have 3 or more leads for connection to an external current is a? |
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Definition
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| 3 purposes of a transistor are? |
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Definition
1- to function as an electronically controlled variable resistance
2- act like a electroniclly ontrolled switch
3- Act as an amplifier to control voltage drops across circuit components |
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The two junctions of a transistor are _______. |
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Definition
collector-base
and
emitter-base |
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Transistors are classified as PNP and ______. |
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Definition
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| The Emitter-Base (EB) must be? |
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Definition
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| The Collector-Base (CB) junction must be? |
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Definition
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| The transistor is constructed in three layers .. |
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Definition
EMITTER – medium sized, gives off or “emits” current carriers (either electrons or holes).
BASE - very small, controls the flow of the current carriers.
COLLECTOR - large, collects the current carriers. |
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| There are two PN junctions in each transistor |
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Definition
Emitter-Base and Collector- Base
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| The schematic symbol for a transistor is labeled with a |
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Definition
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| In the PNP, the arrow will point |
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Definition
| the base (pointing in pointer) |
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| In the NPN, the arrow will point |
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Definition
| away from the base (not pointing in) |
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| The PNP transistor current flow will be |
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Definition
| in the collector and the base and out of the emitter |
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| The NPN transistor current flow will be |
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Definition
| the emitter and out of the collector and base |
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| Electrostatic field and recombination between the materials results in the formation of the emitter-base and collector-base junctions. since the transistor has 2 junctions we need ? |
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Definition
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| Forward bias at the EB junction reduces ? |
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Definition
| the size of the junction barrier. Therefore, the EB junction has a low resistance. |
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| Reverse bias at the CB junction increases |
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Definition
| The size of the CB junction. Therefore, the CB junction has a high resistance. |
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| a static or quiescent condition is? |
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Definition
| means the circuit does not have an input signal and the voltages are fixed in a non-varying condition |
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| In the NPN transistor current entering the emitter will always be___% of the total transister current? |
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Definition
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| NPN Current paths..the emitter current will always be |
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Definition
100% of transistor current..
Base current (IB) will be approximately 5%. Collector current (IC) will be approximately 95%.
Emitter current (IE) is shown leaving the emitter battery (VEE) and flowing to the N-type emitter. |
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| PNP Current Paths..the EB junction will be foward bias..current will flow in the collector and base and out of the emitter..making? |
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Definition
the holes move across the junction rather easily. The base only has a few free electrons to recombine with the holes that crossed the EB junction. These electron hole pairs will become base current, which will be approximately 5% of transistor current.
The collector is P-type but has a strong negative charge which attracts the rest of the holes across the CB junction. These holes will recombine with the electrons
allowing current to flow in the opposite direction of the hole movement. The current flow is collector current 5%. |
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| Increasing forward bias across the EB junction (figure 1-28B) increases the amount of IE, IB, and IC. |
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Definition
| Transistor resistance has decreased. |
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| Decreasing forward bias across the EB junction (figure 1-28C) decreases the amount of IE, IB, and IC |
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Definition
| Transistor resistance has increased |
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| The effect of the relatively small base-to-emitter voltage on base current has? |
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Definition
| has a very large controlling effect on the collector current. |
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| the 2 methods for biasing are? |
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Definition
Base-Current Bias
(Fixed bias) and Combination Bias. |
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On a TO-5 Canister, pin 1 appears next to the ______________. |
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Definition
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