Basic knowledge of electronic components (3) – inductor coil
The inductance coil is * a circle around the wire circle on the insulating tube, wires insulated from each other with each other, while insulating tube is hollow, and can also contain iron or powder cores, referred to as the inductor. With L, the unit Thierry Henry (H) mm Henry (mH), micro-Henry (uH), 1H = 10 ^ 3mH = 10 ^ 6uH.
First, the inductor.
Inductance in the form Category: fixed inductor, variable inductor.
According to the the magnetizer nature: air core coil, ferrite coils, iron core coil, copper coil.
The nature of the work: the antenna coil and oscillation coil, choke coil, notch coils, deflection coils.
Classified by winding structure: single-layer coil, multi-layer coil, honeycomb coil.
Two, the main features of the inductance coil parameters
1, the inductance L
L is inductance of the coil inherent characteristics, has nothing to do with the current size. In addition to the specialized inductive coil (color code inductance), the inductance is generally not specifically marked on the coil, while the specific name label.
2, the inductive reactance XL
Inductor coil on the size of the AC current disincentives that the inductive reactance XL, units of ohms. Its relationship with the inductance L and the AC frequency f XL = 2πfL
3, the quality factor Q
Quality factor Q is a physical quantity Q is the ratio of reactance XL and its equivalent resistance, that is: Q = XL / the R represents the coil quality
The higher the Q value, the smaller the loop loss, the coil. Coil Q value and the DC resistance of the conductor and dielectric loss of the skeleton, shield or core caused by the loss, the impact of the high-frequency skin effect and other factors. Coil Q value is typically tens to hundreds.
4, the distributed capacitance
Turns and turns of the coil, the coil and the shield coil and the capacitance between the bottom plate is called a distributed capacitance. Distributed capacitance of the presence of the coil Q value decreases, the stability becomes worse, and thus the distributed capacitance of the coil as small as possible.
Third, the commonly used coil
1, single-layer coil
The single layer coil is to suffer a circle around the insulated wire circle on the paper or bakelite skeleton. Such as the transistor radio MW antenna coil.
2, the honeycomb coil
If the winding of the coil, the plane is not parallel with the rotating surface, but intersect at an angle, this coil is called the honeycomb coil. The number of revolution, wire back and forth bending, often referred to as discount points. The honeycomb around the law, the advantages of small size, small distributed capacitance, and inductance volume. Are the use of honeycomb honeycomb coil winding machine around the system, the more discount points, distributed capacitance the smaller
3, the ferrite core and iron core coil
The size of the inductance of the coil and whether the core. Insert ferrite cores increase the inductance and improve the quality factor of the coil in the air core coil.
4, copper coils
The copper core coil in the ultrashort wave range of applications more rotating copper core in the coil in the position to change the inductance of this adjustment is more convenient, and durable.
5, color-coded inductors
The color-coded inductors with fixed inductance of the inductor, its inductance sign the same way as the resistance of the same color ring to mark.
6, the choke coil (choke)
Limit the alternating current through the coil, said choke coil, sub-high-frequency choke ring and low-frequency choke ring.
7, the deflection coil
The deflection coil is a load of TV scan circuit output stage, and deflection coil requirements: high deflection sensitivity, uniform magnetic field, high Q value, small size, low price.
The transformer is to transform the AC voltage, current and impedance of the device, when the AC current through the primary coil, the core (or cores) will produce AC magnetic flux, so that the secondary coil induces a voltage (or current). Transformer core (or cores) and the coil, the coil there are two or more windings, which connected the power winding is called the primary coil, the rest of the winding is called the secondary coil.
Cooling methods: (since cold) dry-type transformers, oil immersed (self-cooled) transformers, fluoride (evaporative cooling) transformer.
Moisture-proof ways: open-type transformers, potting-type transformers, sealed transformers.
Core or coil structure: the core-type transformer (plug-chip core, the C-type iron core, ferrite core), core of the shell-type transformers (inserts, C-type iron core, ferrite core), toroidal transformers, metal foil transformers.
Press the power number of phases: single-phase transformers, three-phase transformers, multi-phase transformer.
Uses: power transformers, regulating transformers, audio transformers, IF transformers, high frequency transformer, pulse transformer.
Two, the characteristic parameters of the power transformer
1 operating frequency
Transformer core loss and frequency, it should be based on frequency of use to design and use of this frequency is known as the operating frequency.
2 rated power
Specified frequency and voltage, the transformer can be long-term work, not to exceed the provisions of the temperature rise of output power.
3 rated voltage
In the coil of the transformer allows the voltage applied to the work shall not be greater than the specified value.
4 voltage ratio
Refers to the ratio of the transformer primary voltage and secondary voltage, the difference between no-load voltage ratio and load voltage ratio.
5 no-load current
The transformer secondary is open circuit, the current of the primary is still a certain part of the current is called the no-load current. No-load current (generated magnetic flux) by the magnetizing current and iron loss current (caused by the core loss). For 50 Hz power transformer no-load current is basically equal to the magnetizing current.
No-load loss: refers to the secondary open circuit of the transformer in the primary measured power loss. The main loss is core loss, followed by the no-load current in the primary coil copper resistance loss (copper loss), this part of the loss is small.
Means the ratio of the percentage of secondary power P2 and P1 in primary power. Usually the greater the power rating of the transformer, the higher the efficiency.
8 Insulation resistance
Said the performance of the insulation between the coils of the transformer, between the coil and core. Insulation resistance performance of high and low with the use of insulating materials, to high and low temperature and humid.
Three audio transformers and high-frequency transformer parameters
1 Frequency Response
Refers to the transformer secondary output voltage characteristics with changes in the operating frequency.
If the transformers in the intermediate frequency output voltage U0, when the output voltage (input voltage remains the same) decreased when 0.707U0 frequency range, known as the transformer passband B
Three early secondary impedance
The beginning of the transformer secondary access to the appropriate impedance Ro and Ri, the transformer primary, secondary impedance matching, the ratio of Ro and Ri are called early, the secondary impedance ratio. In the case of impedance matching transformer in the best condition, the transmission efficiency.