Basics concept of Inductors : Coils

1 - Inductors

1.1 - Structure of the coil.

Inductor winding several turns back into the ring, painted EMAY Elementary winding insulation, core coils can be air, or a conductive material such as ferrite or steel core from engineering.

Air-core coils Ferrite core coils

Coil symbol on the diagram: L1 is the air-core coil, ferrite-core coils L2, L3 is adjusted core coil, coil L4 as core technical steel

1.2 - The characteristic quantities of the coil.

a) inductance coefficient (Faraday's Law)
Inductance coefficient is a measure specific to the induced electromotive force of the coil when an electric current runs through the variable.

L = ⁽² .S.10 μr.4.3,14.n ^-7) / l

• 
  
  L: is the inductance of the coil, the unit is Henry (H)


• 
  
  n: number of winding coils.


• 
  
  l: length of the coil is measured in meters (m)


• 
  
  S: is the cross section of the core, in m ²


• 
  
  μr: permeability coefficient of the core material.

b) Comments Resistance
Inductance of the coil is a characteristic quantity for the 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: is the frequency unit is Hz


• 
  
  L is inductance, unit is Henry

Taste test of rolling resistance
wire with AC

* Testing of illustration:
Serial coils with bulbs are then connected to the 12V power source
but with different frequencies through the switches K1, K2, K3, while K1
play a direct current passes through the coil strongest (Because Z L = 0) => so the brightest bulb, while K2 closed 50Hz AC coil passing more yey (by Z L increase) => weak light bulb, when K3 is closed, AC 200Hz go winding through the weakest (from highest Z L) => weakest light bulb.

=> Conclusion: Thank resistance of the coil is proportional to the inductance of the coil and is proportional to the frequency of alternating current, alternating current means with higher frequency coil crossing more difficult, DC frequency f = 0 Hz so with DC coil inductance L Z = 0

c) The resistance of the coil net.

Net coil resistance of the resistor, which can be measured by copper
multimeter, conventional coil resistance qualities, the net
relatively small compared to inductance, resistor of resistor called
resistive losses because the heat generated when the coil operation.

1.3 - Nature of charging or discharging of the coil
* Coil energized: When a current flows through the coil, the coil load a form of magnetic energy is calculated by the formula

W = LI ^2/2

• 
  
  W: energy (June)


• 
  
  L: inductance coefficient (H)


• 
  
  I currents.

Experiments on the charging and discharging of the coil.

In the experiment: When K1 is closed, the current through the coil in ascending (generated by the coil inductance against sudden surge currents) so light bulb slowly, when K1 and K2 interrupt both closed, energy loaded in coil form induced voltage darted back through the bulb as light bulbs flashed
=> Phenomena that coil discharge.

2 - Speaker and Microphone

2.1 - Speaker (Speaker)

Speaker is an application of the coil and magnetic field.

4 Ω speakers - 20W (Speaker)

Design and operation of the speaker (Speaker)

Composition of speakers:

Speakers include a cylindrical magnet interlocking poles, N pole in the middle
and S poles around, between two poles forming a slit from the magnetic field
hard, a coil is attached to diaphragm and is placed in the slot from,
Nearby diaphragm is supported by a soft rubber diaphragm can help to ease
fluctuating exit.

Activities:
When our audio-frequency electric current (AC from 20 Hz => 20,000)
flowing through the coil, the coil creates magnetic field and magnetic equipment
Permanent magnet pushed out, pushed to make coils oscillating =>
speaker membranes vibrating in and vocalize.

Note: Excellent
for we must not put DC on speaker, because the current one
dimensional magnetic field generated only fixed and deflection coil of the speaker only on a
direction and stopped, then direct current through the coil rose sharply (by
no induced voltage in the opposite direction) so that the coil will be
fire.

2.2 - Micro

Micro

Micro structure is essentially a miniature loudspeaker, the structure Micro Micro has the same speaker but within the larger coil wrapped around a lot so the speaker impedance of the coil is very large microphone about 600Ω (impedance speakers from 4Ω - 16Ω) in addition to the microphone membrane is formed very thin and easy to oscillate when sound effects on.
Speakers are devices to convert electrical current into the microphone, the sound also reverse
again, change audio Micro audio-frequency electric current.

2.3 - Relays (Relay)

Relays

The relay is also a coil applications in the production of electronic equipment, the principle of operation of the relay is transformed into magnetic currents through wires Quon, from schools to form the mechanical force via gravity to perform a mechanical movement as the switch opens, opens the itinerary of an automation equipment etc ...

Structure and principle of operation of the relay

3 - Transformer

3.1 - Structure of the transformer.

Transformer is a device to convert AC voltage, composition includes a primary coil (put voltage on) and one or more secondary coils (voltage taken out of use) and wound on a magnetic core can is laminated or ferrite core.

Symbol of transformers

3.2 - Percentage of ring / vol of the transformer.

• 
  
  N 1 and n 2 call is the number of turns on the primary and secondary Quon.


• 
  
  U1 and I1 the voltage and electric current in the primary winding


• 
  
  U2 and I2 is the voltage and electric current from the secondary coil.

We have the following relation:

U1 / U2 = n 1 / n 2 voltage in the primary coil and two secondary proportional to the number of windings round.

U1 / U2 = I2 / I1
Electric current in the coil on both ends inversely proportional to the voltage, ie
if we take the higher voltage for as small lines.

3. 3 - The capacity of the transformer.

The capacity of the transformer depends section of
magnetic core, and depends on the frequency of the alternating current, active transformer
active in the higher frequency for greater capacity.

3.4 - Classification transformer.

* Transformer and Transformer audio source:

Power transformers toroidal power transformers

Frequent power transformer in Cassete, amply .., transformers operate at 50Hz grid frequency, transformer core using E-shaped leaves and I Tonsilic reassembly, transformer ratios ring / vol large .

Audio-frequency transformer used for reverse-phase transformers and transformer circuits to amplify the speaker in the audio output, also used transformer core sheets made from such Tonsilic source transformer, but leaves tonsilic in audio transformer thin more to avoid losses, audio transformers operate at higher frequencies, so have some lower vol ring, when audio-frequency transformer design it is often worth taking the average frequency of about 1kHz - to 3KHz.

* Transformer & High Voltage pulses.

High voltage pulse transformer

Transformer pulse transformer is operating at high frequencies around tens of KHz as transformer of the pulse source, high-voltage transformer. pulse transformer cores made of ferrite, by operating at high frequency pulse transformer for very strong capacity, compared with conventional power transformer with the same weight, the pulse transformer can give a capacity of tens of times more powerful .