Nov 20th, 2008
by Electronics Online.
Electrolytic capacitor or electrolytics condensator or we often call “ELCO” is a type of capacitor that uses an ionic conducting liquid as one of its plates. Typically with a larger capacitance per unit volume than other types, they are valuable in relatively high-current and low-frequency electrical circuits. This is especially the case in power-supply filters, where they store charge needed to moderate output voltage and current fluctuations, in rectifier output. They are also widely used as coupling capacitors in circuits where AC should be conducted but DC should not.
Electrolytic capacitors can have a very high capacitance, allowing filters made with them to have very low corner frequencies.
Electrolytic Capacitor Construction
Aluminum electrolytic capacitors are constructed from two conducting aluminum foils, one of which is coated with an insulating oxide layer, and a paper spacer soaked in electrolyte. The foil insulated by the oxide layer is the anode while the liquid electrolyte and the second foil act as cathode. This stack is then rolled up, fitted with pin connectors and placed in a cylindrical aluminium casing. The two most popular geometries are axial leads coming from the center of each circular face of the cylinder, or two radial leads or lugs on one of the circular faces. Both of these are shown in the picture.
Nov 6th, 2008
by Electronics Online.
In this reading we are going to talk about capacitance. I have to make a distinction here between capacitor and capacitance. A capacitor is a device, whereas capacitance is an electrical property. First we will discuss the capacitor and then the property of capacitance.
We will avoid mathematics where possible.
Construction
As you can see a capacitor is a two terminal device. There is always an insulator between the plates of a capacitor. This should suggest to you that current never flows through a capacitor.
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Capacitance Part I ...
Apr 8th, 2008
by Electronics Online.
This article explain the complete basic theory of magneticm.
MAGNETISM AND ELECTRICITY
Any wire carrying a current of electrons is surrounded by an unseen area of force called a magnetic field. For this reason, any study of electricity or electronics must consider magnetism.
Almost everyone has had experiences with magnets or with pocket compasses at one time or another. A magnet attracts pieces of iron but has little affect on practically everything else. Why does it single out the iron? A compass, when laid on a table, swings back and forth, finally coming to rest pointing toward the North Pole of the world. Why does it always point in the same direction?
These and other questions about magnetism have puzzled scientists for hundreds of years. It is only relatively recently that theories seeming to answer many of the perplexing questions that arise when magnetism is investigated have been developed.
Radio and electronic apparatus such as relays, circuit breakers, earphones, loudspeakers, transformers, chokes, magnetron tubes, television tubes, phonograph pickups, tape and disk recorders, microphones, meters, motors, and generators depend on magnetic effects to make them function.
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Magnetism ...
Apr 7th, 2008
by Electronics Online.
When current flows in a resistance, heat is produced because friction between the moving free electrons and the atoms obstructs the path of electron flow. The heat is evidence that power is used in producing current. This is how a fuse opens, as heat resulting from excessive current melts the metal link in the fuse.
The power is generated by the source of applied voltage and consumed in the resistance in the form of heat. As much power as the resistance dissipates in heat must be supplied by the voltage source; otherwise, it cannot maintain the potential difference required to produce the current.
Any one of the three formulas can be used to calculate the power dissipated in a resistance. The one to be used is just a matter of convenience, depending on which factors are known.
Apr 4th, 2008
by Electronics Online.
When two or more components are connected across one voltage source they form a parallel circuit. The two lamps in figure 1 are in parallel with each other and with the battery. Each parallel path is called a branch, with its own individual current. Parallel circuits have one common voltage across all the branches but the individual branch currents can be different.
The voltage is the same across all components in a parallel circuit.
In figure 1 (pictorial diagram above and the equivalent schematic circuit to the right), the two lamps are actually directly connected to the battery terminals. This is always the case with parallel circuits. If you had 10 components (they don’t have to be lamps) connected in parallel then each side of each component is connected directly to the battery (or other source).
BRANCH CURRENTS
Each resistance (or other components) in a parallel circuit is connected by a conductor directly to the source voltage. Each resistor will draw current from the source according to Ohm’s law, I=E/R, for each branch. The sum of all the branch currents must then be equal to the total current drawn from the source.
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Parallel Circuits ...
