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What type of screwdriver should you use if there’s not enough room for a standard screwdriver?
An offset screwdriver.
Which wrench is good for loosening and tightening odd-size nuts and bolts?
An adjustable-jaw wrench.
(1) A mill file used on flat surfaces.
(2) Triangular file used for removing metal from inside corners.
(3) A round (rattail) file for enlarging round holes.
Why might you use a thread gauge?
When measuring the number of threads per inch when rethreading nuts, or to identify and order the right replacement part.
With what kind of torque wrench would you torque a clamp to 25 inch-pounds?
A 1/4-inch drive, breakaway torque wrench (set at 25 inch-pounds).
How do you reduce the setting on a torque wrench?
Safety wire it at installation with at least 0.020-inch wire.
Run a double strand through the clamp, and twist the ends together.
Why are aircraft wires numbered?
To identify the circuit it belongs to, its gauge size, and other information necessary to relate it to a wiring diagram.
(1) Chafing or abrasion.
(2) High temperature.
(3) Possible use as a handhold or as support for equipment of personal belongings.
(4) Damage from cargo being stored or shifted.
(5) Damage from personnel moving about within the aircraft.
(6) Damage from battery acid or fumes.
(7) Abrasion in the wheel well areas.
It reduces the amount of material and thus its current-carrying capabilities.
How are terminal lugs secured to terminal studs?
What method of splicing is most widely used?
To join segments of electrical circuits and simplify maintenance by providing a means of quick removal and installation of electrical equipment.
How much will thermofit shrink when heated with the heat-shrinking tool?
It is a compact wire bundle with self-contained wire assemblies. It provides a barrier to electrostatic interference. You use it to interconnect electrical and electronic EMP hardened components.
What is the maximum ohm value for a bonding or grounding jumper connection?
What is the purpose of shielded wire?
What kind of solder is preferred for connections in electronics circuits?
What type of solder is preferred when temperature limitations are critical?
Bolted or wired connections never make good electrical contact because of the insulating film on the surface of the metals.Soldered connections, on the other hand behave life one solid metal.
It’s used to remove the oxide film from the surface of metals and keep it removed during soldering.
In time it will eat through the connection and create a high-resistance circuit.
What determines whether you need a soldering iron or a soldering gun for the job?
Use a soldering gun for heavy heating when there’s no chance of damage to sensitive electronic components.
Clean the barrel and then file the tip to the required shape using a flat, fine, single-cut file.
A pool of solder on the tip will reduce surface pitting and oxidation and will increase the time between tip rework.
What unsatisfactory condition would you look for in stranded wire after the insulation has been removed?
What method is used to make shielded wire solder connections?
A 1/2-inch tinned copper shielding-braid mounted on a spring-type cleaning tool and a white rubber ink eraser.
The joint may fracture, resulting in a cold solder joint that offers high resistance to current and may corrode after a period of time.
It should have a shiny, bright appearance, no pits or holes, and a good concave fillet between wire and terminals.
What is the minimum and maximum wrap for connecting a conductor to a turret terminal?
What is the total amperage of a parallel circuit with a 12-volt power source and three resistors with values of 12, 4, and 6 ohms?
It’s a circuit that has parallel resistances connected in series with other resistances.
What units reverse the direction of current flow to the coil (armature) of a DC motor?
Applied voltage minus the induced voltage, which is also referred as counter-electromotive force (CEMF).
Name two ways of varying the strength of CEMF.
When a sine wave starts at zero and increases to its maximum positive or negative voltage, what is this voltage called?
Inductance is a property of a circuit that opposes any change in current flow. Its symbol is L.
What’s the unit of measure for inductance, and what’s its symbol?
The number of turns in the coil, the diameter of the coil, the coil length, and the type of material used for the core.
What factors determine the amount of charge (effectiveness) of a capacitor?
Which transformer windings connect to the source voltage?
Which transformer windings connect to the load side?
What type of core material is required for transformers in low-frequency circuits?
A core of low-reluctance magnetic material.
How do you refer to a transformer if, when you apply 10 volts to the primary, the voltage across its secondary reads 2 volts?
The emitter emits current carriers (electrons or holes), the base controls their flow, and the collector collects them.
NPN and PNP.
An NPN transistor is formed by introducing a thin region of P-type material between two regions of N-type material in a single crystal of germanium or silicon. A PNP transistor is formed by introducing a thin region of N-type material between two regions of P-type material.
The emitter-base junction is forward biased and the collector-base junction is reverse biased.
What happens to some of the electrons that move into the base region in an NPN transistor under normal operation?
Some of the electrons recombine with holes and move out through the base lead in the form of base current (IB) and return to the emitter supply battery VEE.
What’s the current path in an NPN transistor under correct bias?
In an NPN, the current path is from the negative terminal of the emitter supply battery to the emitter. It flows through the emitter to the base. From the base, a small part returns to the positive terminal of the emitter battery. The rest flows from the base through the collector to the positive terminal of the collector battery as collector current (IC).
How does current flow in the external circuit of a PNP transistor compare to current flow in an NPN transistor?
Common emitter, common base, and common collector.
What’s the phase of a common emitter’s input compared to its output phase?
The input is 180° out of phase with the output of a common emitter.
What’s the current gain of a common-emitter transistor circuit?
It has a comparatively low response to high frequencies.
What are the essential items for a DC-power supply to operate?
In a half-wave rectifier, what does grounding either end of the output DC supply for an isolation transformer determine?
What is used to produce a steady DC output of a half-wave rectifier?
An AND gate with an inverter or a NOT gate at the output that changes a low output to a high output and vice versa.
The voltage drop across R1 makes the base and emitter of Q1 the same potential, which cuts off the transistor (Q1). The cutoff condition gives a low output.
In troubleshooting a resistive parallel DC circuit, you find the current has decreased. What would be a probable cause?
A resistor in one of the branches has become open. Total circuit resistance has increased causing the drop in current.
In troubleshooting that same circuit, what reading will you get when you place an ammeter in the branch with the open resistor?
Why must you disconnect a defective component from its circuit when you check it with an ohmmeter?
To keep shunt or parallel loads from affecting the resistance reading.
In a parallel circuit with three branch resistors, how does shorting one resistor affect circuit operation?
Total circuit current would increase greatly.
How does an open in the series part of a series-parallel circuit affect current flow?
Total resistance of the circuit is decreased.
What will a voltmeter read across a good series resistor in a series-parallel circuit?
It will read part of the applied voltage (the voltage dropped by the series resistor).
What is the meter reading on an ohmmeter connected across a shorted component?
Lower than normal or zero will be indicated.
Between the two points to be checked (in parallel).
Set the voltmeter range higher than the voltage being tested and connect to the proper polarity.
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