Power Source Filters Flashcards
What does a filter section of a power supply remove?
It removes ripple
what does removing ripples do?
flattens the pulsating DC wave to make a more consistent load line
Name three characteristics of a filter circuit
- Stores Energy when the current is high
- Releases energy when current is low
- Combination of capacitors, inductors, resistors
What is a Capacitor
A voltage storage device
what type of capacitor is used?
Electrolytic Type
How does a capacitor work?
stores voltage as sine wave builds and releases voltage as sine wave decreases
What is an Inductor
a magnetic field storage device
How does inductor work?
stores magnetic field as sine wave builds and releases magnetic field(current) as sine wave decreases
What is a Resistor?
a voltage-dropping device
How many Ohms is the resistor usually?
usually below 500 Ohms
How many watts is the resistor usually?
high power rating above 2 watts
How are capacitor filters connected in a circuit?
is a capacitor “C” connected in parallel with a load resistance “RL”
the amount of voltage drop before the capacitor begins to charge again is called _____ _____
ripple voltage
What controls the amount of capacitor discharge between voltage peaks
the RC time constant of the capacitor and load resistance
what were to happen if the load resistance and capacitance are large
the ripple voltage will be small, resulting in a smooth output
advantages of a capacitive filter
- Low cost
- low ripple at low load
disadvantages of capacitive filter
- High ripple at high load
over time what could damage circuit fuses and diodes
surge currents
How does an L-section resistive filter reduce surge currents?
using a current-limiting resistor
How should the resistor be connected in an L-section resistive filter
in series with the rectifier
how does the L-section inductive filter reduce surge currents?
using a current-limiting inductor(coil) L1
how do inductors used as series elements oppose changes in current
by creating a counter electromotive force (CEMF) or counter voltage
what happens to the pulses not blocked by the inductor?
they are bypassed by the capacitor
True or False?
The inductor tends to block the pulsating DC voltage
True
What are the two types of Pi Filters
- Inductive
- Resistive
when money is a factor, the inductor is sometimes replaced by ____ in a pi-section filter
resistor
