Basic Coils

1 - Inductors
1.1 - Structure of inductors.
Inductor winding consists of a loop into multiple loops, painted emay winding insulation, core coil may be air, or a conductive material such as ferrite or steel core from engineering.

Air core coil ferrite core coil

The symbol on the diagram coil L1 is air core coils, ferrite core coil L2, L3 is the core correction coils, steel core coil L4 is the technical

1.2 - The characteristic quantities of the inductors.

a) inductance (Faraday's law)
Inductance coefficient is a measure of specific induced electromotive force of the coil when a current is run through 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 turns of the coil wire.
• l: the length of the coil in meters (m)
• S: is the core cross section, measured in m ²
• μr: is the coefficient of permeability of the core material.

b) Inductance
Inductance of the 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 coefficient of inductance unit is Henry

Experiments on the inductance of the coil
AC cord with

* The experiment illustrates:
Coil in series with the lamp is then connected to the 12V power supply
but have different frequencies through switches K1, K2, K3, when K1
DC plays go through the most powerful coil (Since Z L = 0) => so the brightest bulb, while K2 close to 50 Hz alternating current through the coil yey more (by Z L increase) => weak light bulb, the K3 is closed, AC 200Hz to the weakest coil (by the highest Z L) => the 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 passing through coils more difficult, DC frequency f = 0 Hz, so the DC coil with inductance L = Z 0

c) the net resistance of the coil.

Resistance of the coil is pure resistance, which can be measured by the
multimeter, usually good quality coil resistance is pure
be relatively small compared to the inductance, resistance, also known as pure resistance
losses because of this resistance and generate heat when operating coil.

1.3 - Nature of loading or discharging of inductors
* Coils Recharge: 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 (H)
• I current.

Experiments 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 bulb, just disconnect the K1 and K2 is closed, energy loading in coil form larger induced voltage across the lamp back to flashing lights
=> That coil discharge phenomena.

2 - Speaker and Microphone
2.1 - Speaker (Speaker)
Loa is an application of the coil and the magnetic field.

4 Ω Speaker - 20W (Speaker)

Design and operation of the speaker (Speaker)

Structures of speakers:

Speakers include a cylindrical magnet with interlocking poles, pole N in the middle
and S poles around, between two poles forming a gap between the magnetic field
quite strong, a coil is attached to the speaker membrane and placed in the slot from,
loudspeaker membrane is supported by nearly soft rubber membrane helps speakers can easily
out the oscillations.

Activity:
When we are for the current frequency (from 20 Hz AC => 20,000)
running through the coil, the coil creates a magnetic field and magnetic field variations
fixed magnets push, push to make the coil oscillation =>
membrane fluctuations and speakers emit sound.

Note: Excellent
not be taken for DC current to the speaker, the power for a
only way to create a fixed magnetic field coil of the speaker and only a difference of
direction, then stop, then direct current through the coil increased (by
no induced voltage in the opposite direction) so that the coil will be
a fire.

2.2 - Micro

Micro

Essentially composed Micro is a miniature speaker, the speaker but the same composition Micro Micro is the coil winding number larger than many speakers so the impedance of the coil microphone is great about 600Ω (impedance speakers from 4Ω - 16Ω) in addition to micro membrane is composed of very thin and easy to sound vibrations into effect.
Speakers are devices to convert electrical current into sound micro contrast also
again, Micro audio converter audio-frequency electric current.

03/02 - Relay (Relay)

Relays

Relay is a coil applications in electronics manufacturing, the principle of operation of the relay is to transform the current into a magnetic field through quon wire, a magnetic field to form a mechanical force through the attraction to perform an action such as opening and closing of mechanical switches, opening and closing of a journey automation equipment etc. ...

Design and principle of operation of relay

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

Symbols of the transformer

3.2 - Percentage of ring / vol of the transformer.

• Call n 1 and n 2 is the number of turns of primary and secondary quon.
• U1 and I1 is the voltage and electric current in 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 at the two ends of the coil is inversely proportional to the voltage, ie
If we take the higher voltage for the smaller line.

3. 3 - Power of the transformer.

The dependence of the transformer section of
core, and depending on the frequency of alternating current, transformers running
work at higher frequencies for greater production.

3.4 - Classification of transformers.

* Transformer power transformer and frequency:

Power transformer toroidal power transformer

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

Audio-frequency transformer used as the island phase transformer and transformer circuits to the speaker in the capacity of audio-frequency amplifier, transformer and leaf Tonsilic to use as transformer cores from the source, but leaves tonsilic in audio-frequency transformer thin to prevent further loss, audio frequency transformers operating at higher frequencies, so a lower number of vol ring, when audio-frequency transformer design people often take the average value of about 1KHz frequency - to 3KHz.

* High pressure & pulse transformers.

High voltage pulse transformer

Pulse transformer is a transformer operating at high frequencies a few 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 with conventional power transformer of the same weight, the pulse transformer for export may be ten times stronger than .