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What are the four basic sections of a power supply?
- Transformer
- Rectifier
- Filter
- Regulator.
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What is the purpose of the rectifier section?
To change ac to pulsating dc.
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What is the purpose of the filter section?
To change pulsating dc to pure dc.
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What is the purpose of the regulator section?
To maintain a constant voltage to the load.
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What is the name of the simplest type of rectifier which uses one diode?
The half-wave rectifier.
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If the output of a half-wave rectifier is 50-volts peak, what is the average voltage?
15.9 volts.
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In addition to stepping up or stepping down the input line voltage, what additional purpose does the transformer serve?
It isolates the chassis from the power line.
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What was the major factor that led to the development of the full-wave rectifier?
The fact that the full-wave rectifier uses the full output, both half cycles, of the transformer.
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What is the ripple frequency of a full-wave rectifier with an input frequency of 60 Hz?
120 hertz.
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What is the average voltage (Eavg) Output of a full-wave rectifier with an output of 100 volts peak?
63.7 volts.
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What is the main disadvantage of a conventional full-wave rectifier?
Peak voltage is half that of the half-wave rectifier.
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What main advantage does a bridge rectifier have over a conventional full-wave rectifier?
The bridge rectifier can produce twice the voltage with the same size transformer.
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If you increase the value of the capacitor, will the XC increase or decrease? Why?
It will decrease. Capacitance is inversely proportional to XC.
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What is the most basic type of filter?
The capacitor filter.
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In a capacitor filter, is the capacitor in series or in parallel with the load?
Parallel.
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Is filtering better at a high frequency or at a low frequency?
At a high frequency.
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Does a filter circuit increase or decrease the average output voltage?
A filter circuit increases the average output voltage.
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What determines the rate of discharge of the capacitor in a filter circuit?
Value of capacitance and load resistance.
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Does low ripple voltage indicate good or bad filtering?
Good.
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Is a full-wave rectifier output easier to filter than that of a half-wave rectifier?
Yes.
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In an LC choke-input filter, what prevents the rapid charging of the capacitor?
The CEMF of the inductor.
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What is the range of values usually chosen for a choke?
From 1 to 20 henries.
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If the impedance of the choke is increased, will the ripple amplitude increase or decrease?
Decrease.
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Why is the use of large value capacitors in filter circuits discouraged?
Expense.
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When is a second RC filter stage used?
When ripple must be held at an absolute minimum.
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What is the most commonly used filter today?
LC capacitor-input filter.
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What are the two main disadvantages of an LC capacitor filter?
Cost and size of the inductor.
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Circuits which maintain constant voltage or current outputs are called dc voltage or dc current ___.
Regulators.
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The purpose of a voltage regulator is to provide an output voltage with little or no ___.
Variation.
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The two basic types of voltage regulators are ___ and ___.
Series and shunt.
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When a series voltage regulator is used to control output voltages, any increase in the input voltage results in an increase/a decrease (which one) in the resistance of the regulating device.
An increase.
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A shunt-type voltage regulator is connected in serial/parallel (which one) with the load resistance.
In parallel.
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A half-wave voltage doubler is made up of how many half-wave rectifiers?
Two.
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If a half-wave rectifier is added to a half-wave voltage doubler, the resulting circuit is a voltage ____.
Trippler.
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In a full-wave voltage doubler, are the capacitors connected in series or in parallel with the output load?
In parallel.
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What is the most important thing to remember when troubleshooting?
Safety precautions.
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What is the main reason for grounding the return side of the transformer to the chassis?
To eliminate shock hazard.
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What are two types of checks used in troubleshooting power supplies?
Visual and signal tracing.
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