Lesson 10 Flashcards#
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1. What is the most basic AC-to-DC converter?
A half-wave rectifier.
2. What is a diode?
A diode is an electronic one-way valve for current — it allows current to flow in one direction but blocks it in the opposite direction.
3. What is a capacitor?
A capacitor is an electrical energy storage device (it stores charge). It acts like a temporary battery in that when a voltage is applied, the capacitor charges up to that voltage.
4. What are negative currents?
Currents that flow in the opposite direction to the defined positive reference direction.
5. What are negative voltages?
Voltages that are below the reference point, typically ground, indicating a potential difference in the opposite direction.
6. What does rectified mean?
"Rectified" means the negative portion of the AC waveform has been removed or flipped, leaving an output that is unidirectional (only positive). The result is a form of DC, though a very pulsating one (not steady).
7. How much voltage does a capacitor hold?
It charges up to whatever voltage is applied across it (the capacitor's voltage will match the source voltage at full charge).
8. In what configuration is the load connected with the capacitor?
In parallel with the capacitor.
9. What is voltage ripple with a capacitor?
Voltage ripple is the small variation in the DC output voltage due to the capacitor charging and discharging. In other words, it's the peak-to-valley voltage swing that remains on the DC output as the capacitor supplies the load between rectifier pulses.
10. What are the steps in AC-to-DC conversion?
- Transform: Get to the right voltage
- Rectification: Get the signal positive
- Smoothing: Reduce the push–pause–push using a capacitor
- Regulation: Set the output voltage to the desired level and eliminate remaining ripple
11. What is XFMR in a block diagram?
XFMR stands for transformer, which is used to change voltage levels in AC-to-DC conversion.
12. What does AC/DC mean in a block diagram?
AC/DC refers to the conversion process from alternating current (AC) to direct current (DC).
13. What is the advantage of a full-wave rectifier over a half-wave rectifier?
A full-wave rectifier uses both the positive and negative halves of the AC waveform (flipping the negative half positive), so the capacitor is recharged twice per cycle instead of once. This produces less ripple and a higher average output voltage for the same capacitor size.
14. What does a voltage regulator do in an AC-to-DC converter?
A voltage regulator holds the output voltage steady at a fixed value regardless of changes in load current or remaining ripple. It eliminates the residual AC variation left after smoothing and ensures the output matches exactly what the downstream electronics require.
15. How does ripple voltage change if the load draws more current?
Ripple increases. A heavier load discharges the capacitor faster between rectifier pulses, so the voltage drops more before the next pulse recharges it — resulting in a larger peak-to-valley swing on the output.