TEST 3 ECET 205

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a transistor can be tested using a voltmeter to check back and front resistances of emitter base, collector base, and collector emitter

false

digital circuits are often called two-state circuits because their q point always remains in the active region

false

hard saturation of a transistor results when there is just enough base current to cut off the transistor.

false

most analog VOMs have a special forward current gain test function.

false

the operating point found on a load line is labeled C because this point is often called the cut-off point

false

the two basic kinds of transistor circuits are rectifying and oscillating

false

what is the term used to describe when there is more than enough base current to saturate a transistor.

hard saturation

Voltage divider bias produces a fixed value of emitter current that results in a stable operating point that is the _________ current gain

independent

The main advantage of an octocoupler is electrical _________ between input and output circuits

isolation

coupling capacitors between transistor stages appear as _____ circuits to dc voltage and currents.

open

a photo-transistor has more sensitivity to light that a(n) ____________

photodiode

a _________ transistor is used when the electronics equipment has a negative power supply

pnp

the operating point on the load line is labeled Q because this point is called the

quiescent point

when the collector current has increased to its maximum possible value it is said to be in ________

saturation

collector feedback is also called

self bias

Collector feedback bias is also called

self-bias

collector feedback bias is still sensitive to changes in current gain, but it is used because of its

simplicity

the two kinds of transistor circuits are amplifying and ________

switching

the schematic diagram of a pnp transistor shows

the emitter as an arrow pointing in

Emitter feedback and collector feedback are typically not adequate because

there is not enough negative feedback

while testing a transistor with an ohmmeter, a high reverse/forward resistance ratio for the emitter base and base collector junctions indicates

this transistor is good

A transistor goes into saturation when the collector current has increased to its maximum possible value

true

switching circuits are usually designed to operate at saturation and cutoff

true

with amplifying circuits, the q point must remain in the active region under all operating conditions

true

the intent of emitter feedback bias is to swamp out the _______ in current gain.

variations

the mostly widely used transistor biasing circuit is called _______ bias

voltage divider

with a pnp transistor the base emitter junction will be forward biased

when the emitter voltage is 0.7V above the base voltage

what occurs when the line voltage is changing polarity from positive to negative or vice versa?

zero crossings

Transistor replacement, collector current changes, or temperature changes can produce large changes in

Beta DC

The voltage between emitter and ground is called the _________ voltage

emitter

historically, the first attempt at stabilizing the operating point of a transistor circuit was to use

emitter feedback bias

to prevent meter loading, a voltmeter used to make transistor circuit voltage measurements should have an input impedance of __________ ohms

10 Mega

using a firm voltage divider means that the collector current will be approximately

10 percent lower than the stiff value

A firm voltage divider means that the collector current will be approximately 10 percent higher than the stiff value.

False

A well designed voltage divider bias circuit is one in which the voltage divider appears stiff to the output resistance of the collector

False

Emitter feedback bias uses a capacitor that provides positive feedback in attempt to stabilize the operating point.

False

Emitter feedback has always been very popular

False

Since voltage-divider bias is derived from emitter bias, the Q point varies with the changes in current gain.

False

Voltage Divider bias is really collector bias in disguise

False

a two supply emitter bias circuit typically used in transistor circuits is the most popular method of providing transistor bias.

False

Whenever possible a designer will configure a stiff voltage divider for base bias because it will produce a stable Q point.

True

collector feedback bias is also called self bias

True

By exposing a transistors collector junction to light a manufacturer can produce

a photo-transistor

amplifier that use emitter bias have Q points that

are immune to changes in current gain

establishing a fixed value of base current is a result of _________ bias

base

what should a trouble shooter do if the base, collector, and emitter voltages in a transistor circuit all measure 0 V?

check supply voltage and leads

The saturation point determines the maximum

collector current for the circuit

the ___________ point determines the maximum possible collector to emitter voltage

cutoff

___________ circuits use base bias and are designed to operate at saturation and cutoff.

digital

with ambiguous troubles, the troubleshooter very often must

disconnect one suspected component and test it


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