Basics: The coil

1 - Inductors

1.1 - Structure of the inductors.

Inductors are a number of coils wound into multiple loops, winding painted emay insulating core coil may be air, or a conductive material such as ferrite or steel cores from the techniques.

 

Air core coil ferrite core coil

Symbols on the diagram coil L1 is air-core coils, ferrite core coil L2, L3 are adjusted core coil, the coil L4 is the technical core steel

1.2 - The quantity characteristics of inductors.

a) inductance (Faraday's law) 
coefficient is a measure of self-induction electromotive force characteristic for the induction of the coil when a current is run through the variations.

L = (μr.4.3, 14.n ² . S.10 ^-7 ) / l

• L is the inductance of the coil, the unit is Henrry (H)
• n: the number of winding coils.
• l: the length of the coil in meters (m)
• S: is the core cross section, measured in m ²
• μr: the coefficient of permeability of the core material.

b) Inductance
Inductance coil is a measure of specific resistance of the coil current to alternating current.

Z L = 2.3,14. FL

• Where: Z L is the inductance, the unit is Ω
• f: the frequency unit is Hz
• L is the inductance factor, the unit is Henry

Experiments on the inductance of the coil 
wire to the AC

* The experiment illustrates:
The coil in series with the lamp is then connected to the 12V power source 
but have different frequencies through the switches K1, K2, K3, K1 to 
close the DC current passes through coils strongest wireless (Since Z L = 0) => so the brightest bulb, while K2 plays 50Hz alternating current passes through the coil yey more (by Z L increase) => weak light bulb, the K3 close , 200Hz alternating current through the coil to the weakest (by Z L highest) => weakest light bulbs.

=> Conclusion : Inductance of the coil is proportional to the inductance of the coil and is proportional to the frequency of alternating current, alternating current means a higher frequency coil passing more difficult, DC frequency f = 0 Hz, so the direct current inductance coil is Z L = 0

c) the net resistance of the coil.

Resistance of the coil is pure resistance, which can be measured by the 
multimeter, the coil is usually good quality pure resistor 
must be relatively small compared to the inductance, resistance, also known as pure resistance 
the resistive losses due to this coil generates heat when operating.

1.3 - Nature of loading and discharge of the inductor
coil * Recharge : When a current flows through the coil, coil loading a form of magnetic energy is calculated by the formula

W = LI ² / 2

• W: Energy (June)
• L: inductance (H)
• I current.

The experiment on the charging and discharging of the coil.

In the experiment: When K1 is closed, current through the coil increases (generated by the coil inductance against current surge) so light from the lamp, when both K1 and K2 closed off, energy loaded in the coil form larger induced voltage across the lamp back lamp as Flashlight 
=> coil that discharge phenomena.

2 - Speaker and Micro

2.1 - Surround (Speaker)

Loa is an application of the coil and magnetic field.

Speaker 4 Ω - 20 W (Speaker)

Design and operation of the Speaker (Speaker)

Components of the speakers:

Speakers include a cylindrical magnet poles are nested, in the extreme N 
and S poles around, between two poles form a gap between the magnetic field 
is quite strong, a coil attached to the speaker membrane and placed in the slot from, 
the speaker diaphragm is supported by nearly soft rubber membrane helps the speaker can easily 
fluctuate in and out.

Activity :
When one frequency to current (AC power from 20 Hz => 20,000) 
running through the coil, the coil creates a magnetic field and magnetic field variation 
of the magnet fixed push, push to make oscillator coil => 
membrane fluctuations and the speaker emits sound.

Note : Great 
for us not to direct current to the speaker, the power for one 
-way only creates a fixed magnetic field coil of the speaker and the only difference of a 
direction, then stop, then the direct current through the coil increase (because 
there is no induced voltage in the opposite direction) so the coil will 
burn.

2.2 - Micro

Micro

Essentially composed Micro is a miniature speaker, the speaker but same texture Micro Micro is the coil winding on a larger lot so the speaker impedance of the coil microphone is great about 600Ω (impedance speakers from 4Ω - 16Ω) in addition to micro membranes are composed of very thin so easy when the sound vibrations on impact. 
Loa is a device to convert sound into electrical current while the opposite microphone 
, the sound of the Micro Change electrical frequency.

2.3 - Relay (Relay)

Relays

Relay is a coil applications in electronics manufacturing, the principle of operation of the relay is transformed into electricity through quon magnetic wire, magnetic fields to create mechanical force via gravity to perform a mechanical action such as opening and closing switches, opening and closing the journey of an automatic device etc. ...

Design and principle of operation of the relay

3 - Transformer

3.1 - Structure of the transformer.

Transformer is a device to convert AC voltage, the composition includes a primary winding (to the voltage on) and one or more secondary coils (used to take the output voltage) and wound on a core can leaf steel or ferrite core.

The symbol of the transformer

3.2 - Percentage of ring / vol of the transformer.

• Call  n 1 and n 2 is the number of turns on primary and secondary quon.
• U1 and I1 is the voltage and current into primary winding
• U2 and I2 is the voltage and electric current from the secondary coil.

We have the following formula:

U1 / U2 = n 1 / n 2 voltage on primary coil and two secondary proportional to the number of turns winding.

U1 / U2 = I2 / I1
currents in the two coils is inversely proportional to voltage, that is 
if we get a higher voltage for smaller lines.

3. 3 - The output of the transformer.

The dependence of the transformer section of the 
core, and depends on the frequency of the alternating current, the transformer works 
in the higher frequencies for greater production.

3.4 - Classification of the transformer.

* Power transformer and transformer frequency:

 

Power transformer toroidal power transformer

Frequent power transformer in cassete, amply .. , The transformer operates at a frequency of 50 Hz grid, transformer core using the E-shaped leaves Tonsilic and I put together, this ratio transformer ring / large vol.

Audio-frequency transformer used as the island phase transformer and the transformer in the speaker circuit capacity of audio-frequency amplifier, a transformer is used as leaf Tonsilic transformer core as source, but leaves tonsilic frequency transformer in thin than to avoid losses, frequency transformers operate at higher frequencies, so there are lower volumes of round, when the frequency transformer design is often worth taking the average frequency of about 1KHz - to 3KHz.

* High pressure & pulse transformers.

 

High voltage pulse transformer

Pulse transformer is a transformer operating at high frequencies around tens of KHz as the transformer in the power pulse, high-voltage transformer. pulse transformer cores made of ferrite, by operating at high frequency pulse transformer for export is very strong, compared to conventional power transformers of the same weight, the pulse transformer can be for dozens of times stronger than .