1. Proper understanding of the definition of capacitors. 2.
Identify the relationship between a resistor and a capacitor. 3.
Calculate capacitance in series and parallel circuit and in terms
of same capacitance value. 4. Classify capacitors according to
materials and usage. 5. Relate the topic to everyday living.
Slide 3
A capacitor is a device that stores electrons. The basic
capacitor is made up of two conductors separated by an insulator,
or dielectric. Depending on how the capacitor is built, the
dielectric can be made of paper, plastic, mica, ceramic, glass, a
vacuum or any other such non conductive material.
Slide 4
Capacitor electron storing ability (its capacitance) is
measured in Farads. 1 Farad is actually a huge number of electrons
(6, 280, 000, 000, 000, 000, 000 electrons to be exact), so we
usually rate capacitors in microfarads (F) and picofarads
(pF).
Slide 5
1 F is equal to 0.000001 F 1 pF is equal to 0.000000000001
F
Slide 6
Capacitors comes in a variety of sizes, shapes, models, or if
you so desire they can be manufactured by your specifications.
Slide 7
Capacitors also come in a variety of materials, to name a few :
Aluminum foil, Polypropylene, Polyester (Mylar), Polyesterene,
Polycarbonate, Kraft Paper, Mica, Teflon, Epoxy, Oil-filled,
Electrolyte, Tantalum, and the list goes on. Latest product (in
reseach) is Nobium.
Slide 8
The value of a capacitor can vary from a fraction of a
picofarad to more than a million F ( means micro). Voltage levels
can range from a couple to a substantial couple hundred thousand
volts.
Slide 9
It can store electric charge even though the voltage source is
already disconnected. It can discharge electrical voltages.
Slide 10
Slide 11
An early classification is settled for capacitors. These were
stablished and categorized into four namely (a)non-polarized,
(b)polarized, (c) variable, and (d) trimmer.
Slide 12
Non-polar capacitor is a type of capacitor that can be
connected any way in a circuit. In other words, there is no
positive or negative. Common types of non-polar capacitors are
ceramic,mica and some electrolytic.
Slide 13
There are two types of non- polarized capacitors. The plastic
foil that are non polarized by nature and electrolytic non
polarized capacitors that are actually two capacitorsin series
(back to back) so that the result is non polarized with half the
capacitance.
Slide 14
A capacitor stores electric charge. This type must be connected
the correct way around. A capacitor stores electric charge. A
capacitor is used with a resistor in a timing circuit. It can also
be used as a filter, to block DC signals but pass AC signals.
Slide 15
Polarized capacitors are the electrolytic type or tandalium
type. They have large leakage current if the voltage is inverted.
They are cheaper than equivalent non-polarized capacitors. They are
sometimes physically smaller that non-polarized equivalents. They
are meant for AC signals respectively.
Slide 16
Electrolytic capacitors have a polarity unlike other
capacitors. This is due to the fact that aluminum oxide layer is
held in place by the electric field, and when reverse- biased, it
dissolves into the electrolyte. This allowsa short circuit between
the electrolyte and the aluminum.
Slide 17
Non-polarized capacitor has a big size with the smaller
capacitance, and is used both in DC or AC circuits, low or high
frequencies. Polarized capacitor has a small size with the large
capacitance, and is used only in DC circuits or circuits related to
DC current.
Slide 18
Non-polarized capacitor has a very small leakage current, high
frequency response of up to hundreds of GHz up to types. Polarized
capacitor has a large leakage current low frequency response of
only up to about tens of kHz at aluminum or 1MHz at tantalium
caps.
Slide 19
In general, they cannot replace each other!!!
Slide 20
A variable capacitor is a capacitor whose capacitance can be
varied. These are usually made up of one or more moving plates and
one or more non moving plates separated by the dielectric. By
moving the plates, we can vary the capacitance. A variable
capacitor is used in a radio tuner.
Slide 21
This type of variable capacitor (trimmer) is operated with a
small screwdriver or similar tool. It is designed to be set when
the circuit is made and then left without further adjustment.
