Everything on electronics - Manual of electronics:

The components liabilities include/understand the resistance, capacitores, inducers, transforming, etc.

In this chapter we will analyze the three components more important liabilities: Resistance, Capacitores and Inductores.

The resistance is one of the essential components in the construction of any electronic equipment, since it allows to suitably distribute to the tension and electrical current to all the necessary points.

The value of the resistance is expressed in ohm, which we represented with the symbol W.

If we put under the ends of a resistance the passage of a DC it will produce in the same proportional voltage drop to his value. The intensity crosses that it will be also proportional to the applied tension and the value in ohms of the resistance. In order to calculate this relation it does not have but that to apply the Law of Ohm: I=V/R.

There are two forms to associate resistance in a circuit: association series and parallel association:

which indicates to us that a single resistance of value RT will behave of the same form that the n resistance R1, R2, R3… Rn connected in series.

Also that in the association series, R1, R2, R3… Rn. Nótese that always the value of resistance RT of a parallel association is minor who the Rn minor of the parallel.

The resistance have a color code that indicates its value. This code is made up of bands of colors divided in two groups; first it consists of three or four of these bands, of which the first two or three indicate the nominal value of the resistance and the last one is a multiplier to obtain the scale. The second group is made up of a single band and is the tolerance expressed in percent, this tolerance gives the field us of values within which is the correct value of the resistance.

Digits			Multiplier			Tolerance
	Black	0		Silver plating	10-2		Silver plating	± 10%
	Brown	1		Gilded	10-1		Gilded	± 5%
	Red	2		Black	100		Brown	± 1%
	Orange	3		Brown	101
	Yellow	4		Red	102
	Green	5		Orange	103
	Blue	6		Yellow	104
	Violet	7		Green	105
	Gray	8		Blue	106
	Target	9

Of this form if we have a resistance whose color code is green, black, orange, golden we will have a resistance of 50,000 W and its tolerance is of ± 5%.

In the market it is not possible to find all the values of resistance, but only the standardized ones, which are:

The complete table represents the values for the resistance whose tolerance is of 5%.

In order to obtain all the range of values the previous values by the multipliers already specified in the table of color codes multiply.

Besides being the resistance characterized by their value and tolerance, these are defined by their power of power dissipation, the most typical values are: 1/8, 1/4, 1/3, 1/2, 1 and 2 W, with tolerances of 1%, 2%, 5%, 10% and 20%.

Also resistance of variable value exist called variable resistors or potentiometers, which are very used when it is necessary to realize on a circuit some type of internal adjustment. Also they are used to correct external, such as the case of gain control, tone, luminosity, etc.

The capacitores never are absent either in the electronic circuits, these consist basically of two separated metallic plates by an insulating material (called dielectric). This dielectric material can be air, mica, paper, ceramics, etc.

The value of a capacitor is determined by the surface of the plates and by the distance among them, the one that is determined by the thickness of the dielectric, this value is expressed in terms of capacity. The unit of measurement of this capacity is the farad (f). The used values of capacity actually are much more small that the unit, therefore, these values will be expressed in microfarads (1 mF = 1 x 10-6 F), nanofaradios (1 HF = 1 x 10-9 F) or picofaradios (1 RF = 1 x 10-12 F).

When a continuous tension between the plates of a capacitor is applied, there will be circulation of no current by the same, due to the presence of the dielectric, but an accumulation of electrical charge in the plates will take place, being polarized the capacitor.

Once extracted the applied tension, the capacitor will remain loaded due to the electrical attraction between the faces of the same, if next these faces are cortocircuitan, will take place the unloading of the same, producing a current of unloading between both.

If now we applied an alternating current voltage to him will be put under the capacitor to a continuous tension during half cycle and to the same tension, but in inverse sense, during the other half of the cycle. The dielectric will have to support alternating efforts that vary very quickly of sense, and therefore, its polarization will have to change as the electric field changes its sense, then if we increased to the frequency the dielectric no longer it will be able to possibly follow these changes, taking place a diminution in the capacity. In synthesis, the capacity of a capacitor falls as increases

The condensers, like the resistance, can be connected in series as much as in parallel:

Much variety of capacitores exists to which to types it talks about. Which exist ceramic, that is constructed normally by a tubular base of this material with their metalised surfaces inner and outer with silver, on are the terminals of the same. They are applied so much in low as in high frequencies.

Another type is the one of plastic, that is made with two metalised polyester strips in a face and coiled to each other. This type of capacitor is used to low frequencies or average. With this type of capacitor capacities lifted to tension of up to 1,000 can be obtained V.

Also they exist capacitores electrolytic, which present/display the greater capacity of all for so large determining. They can be of aluminum or tantalum. First they are formed by a leaf of this metal covered by an aluminum oxide layer that acts like dielectric, on oxide there is a lamina of paper absorbed in a conductive liquid called electrolyte and on her one second aluminum lamina. They are of fixed polarity, that is to say that only can work if the outer continuous tension with the positive is applied to them to the corresponding anode. Loss and average frequency are used in.

The passage of current by a conductor goes accompanied by magnetic effects, that is to say that are created a magnetic field by the circulation of current.

When to this magnetic field energy is transferred to him, the FEM source carries out work, which requires electric power, and this power is equal to the current multiplied by the tension, then it must have a voltage drop in the circuit while the energy is stored in the field. This voltage drop is product of an opposite tension that is induced in the circuit while the field varies, when this taking then constant value the induced FEM disappears. As the induced FEM is against the applied one, then this one is against to the variations in the magnetic field.

The amplitude of this FEM is proportional to the variation of the current and the inductance of the circuit. The inductance depends on the physical characteristics of the conductor. If to a conductor is coiled it, will have a greater inductance than when it was not it, in addition as it increases the amount of returns, it also increases the value of the inductance. The inductance will be increased still more when the winding becomes around an iron.

The inductance is moderate in henries (h), and the values used for the different applications vary widely.

All the conductors have inductance, if it is of short length his inductance is small, but will be necessary to have it in account if the current varies quickly in the same.

For the calculation of the inductance of a winding the following formula is used: