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46483 2008 年 01 月 13 日 01:22 Reading (loading. ..) Comments (1) Category: Personal Diary
Capacitors is widely used in electronic equipment electronic components, widely used in blocking, coupling, bypass, filtering, tuning circuits, energy conversion, control circuit and so on. Expressed with C capacitance, farad capacitor unit (F), microfarad (uF), Pi Fala (pF), 1F = 10 ^ 6uF = 10 ^ 12pF
one capacitor type nomenclature
; domestic capacitor models generally consists of four parts (not for pressure-sensitive, variable, vacuum capacitor.) In turn represent the name of the material, classification and serial number.
Part I: names, letters, capacitor C.
Part II: materials, with letters.
Part III: Classification, general use digital said that individual with the letters.
Part IV: serial number, use numerals.
material products with letters: A-tantalum electrolytic, B-polystyrene and other non-polar films, C-high-frequency ceramic, D-aluminum, E-electrolysis of other materials, G-alloy electrolysis, H- composite media, I-glass glaze, J-metallized paper, L-polyester polar organic thin film, N-niobium electrolysis, O-glass membrane, Q-film, T-low-frequency ceramics, V-mica paper, Y- Mica, Z-paper dielectric
Second, the classification of the capacitor
1, in accordance with the structure into three main categories: fixed capacitors, variable capacitors and trimmer capacitors.
2, classified by the electrolyte are: organic dielectric capacitor, inorganic dielectric capacitor, electrolytic capacitors and air-dielectric
quality capacitors.
3, divided by end-use: high-pass, low pass, filtering, tuning, high coupling, low coupling,
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capacitors.
4, frequency bypass: ceramic capacitors, mica capacitors, glass, film capacitors, polyester capacitors, glass capacitors
enamel device.
5, low frequency bypass: paper capacitor, ceramic capacitor, electrolytic capacitors, polyester capacitors.
6, filter: electrolytic capacitors, paper capacitors, composite paper capacitor, wet tantalum capacitors.
7, tuning: ceramic capacitors, mica capacitors, glass, film capacitors, polystyrene capacitors.
8, high-frequency coupling: ceramic capacitors, mica capacitors, polystyrene capacitors.
9, low coupling: paper capacitor, ceramic capacitor, electrolytic capacitors, polyester capacitors, solid tantalum capacitors
device.
10, small capacitors: metallized paper capacitor, ceramic capacitor, electrolytic capacitors, polystyrene capacitors, solid tantalum capacitors, glass glaze, capacitors,
handbags online cheap, metallized polyester capacitors, polypropylene capacitors, mica capacitors.
three commonly used capacitors
1, electrolytic capacitors
electrolyte paste with water soaked paper clip in the middle of the winding and the two foil Cheng, thin oxide film as the medium of the capacitor. because the conductive oxide film are one-way nature, electrolytic capacitors have polarity. capacity, can withstand a large pulse of current, capacity error, leakage current; not suitable for general In the high-frequency and low temperature applications, should not use frequencies above 25kHz low-pass, signal coupling, power supply filtering.
capacity :0.47 - 10000u
rated voltage :6.3 - 450V
main features: small size, capacity, loss of big, big
leakage applications: power supply filtering, low-frequency coupling, decoupling , bypass
2, tantalum electrolytic capacitor (CA) niobium electrolytic capacitors (CN)
made of sintered tantalum anode block, the use of solid manganese dioxide electrolyte temperature characteristics, frequency characteristics and reliability are better than normal electrolytic capacitors, especially the leakage current is very small, the storage of a good, long life, capacity, error is small, and small size, the unit can get the maximum volume under the product of the capacitor voltage tolerance of the ripple current poor, if the damage was easy to short-circuit condition in the ultra-small high-reliability parts.
capacity :0.1 - 1000u
rated voltage :6.3 - 125V
main features: loss, leakage less than electrolytic capacitors
applications: in the demanding circuit in place of aluminum electrolytic capacitors
3, film capacitors and paper capacitors
structure similar, but with polyester, polystyrene and other plastic materials for medium frequency low-loss characteristics, and dielectric loss can not make a large-capacity, poor heat filter, integral, oscillations, timing circuits.
a polyester (PET) capacitor (CL)
capacity: 40p - 4u
rated voltage :63 - 630V
main features: small size, large capacity,
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applications: less demanding on the stability and the loss of low-frequency circuit
b polystyrene capacitor (CB)
capacity: 10p - 1u
Rated voltage: 100V - 30KV
Main features: stable, low loss, larger
applications: loss of stability and require a higher circuit
c polypropylene capacitors (CBB)
capacity: 1000p - 10u
Rated Voltage :63 - 2000V
main characteristics: performance and polystyrene similar but small in size, stability, slightly worse
applications: most of polystyrene or mica instead of capacitors, used to require higher circuit
4
feedthrough ceramic capacitor or ceramic capacitor pillar structure, which is an electrode mounting screws. Minimal lead inductance, frequency characteristics, and dielectric loss, a temperature compensation can not make a large capacity, the capacity change caused by the vibration will be particularly suitable for high frequency bypass.
a high-frequency ceramic capacitor (CC)
capacity :1 - 6800p
rated voltage :63 - 500V
main features: high-frequency loss, good stability
Application : High frequency circuit
b frequency ceramic capacitor (CT)
capacity: 10p - 4.7u
Rated voltage: 50V - 100V
main features: small size, low cost, big loss , poor stability
applications: less demanding low-frequency circuit
5, monolithic capacitors
(multi-layer ceramic capacitor) in a number of films on the ceramic thin film coating to the electrode paddle blanks material, a composite formed after the first round indivisible whole, the outside envelope made of resin and then a small volume, large capacity, high reliability and a new type of high temperature capacitors, high frequency dielectric constant also has a stable monolithic capacitors performance, small size, Q values of high-capacity larger error noise bypass, filter, integral, oscillating circuit.
Capacity range: 0.5PF--1UF
pressure: two times the rated voltage.
large capacity, small size, high reliability, capacity and stability, high temperature and good humidity.
Applications: Widely used in electronic precision instruments. A variety of small electronic devices for resonance, coupling, filtering, bypass.
6, paper capacitors
two aluminum foil is generally used as the electrode, separated by a thickness of 0.008 ~ 0.012mm overlapping winding capacitors are separated from paper. Manufacturing process is simple, cheap, can get a larger capacity
generally low-frequency circuit, usually not more than 3 ~ 4MHz frequency on the use. Oil capacitor voltage capacitors than ordinary paper, stability Ye Hao, suitable for high voltage circuit.
7, trimmer
capacity can be adjusted within a small range, and can be adjusted to a fixed capacitor value. Ceramic trimmer capacitors of Q value is high, the volume is also small, usually tubular and the wafer can be divided into two. Mica and polystyrene media usually use spring-East, simple structure, but less stable. Wirewound ceramic trimmer capacitors are removed copper to changes in capacitance, so capacity can only be smaller, not suitable for the occasion to be used over and over again.
a
air dielectric variable capacitor can be transforming capacity :100 - 1500p
main features: loss of small, high efficiency; available upon request made straight, linear wavelength, linear style and the frequency
type, and so the number of applications: electronic equipment, radio and television equipment
b
film dielectric variable capacitor can be transforming capacity :15 - 550p
main features: small size, light weight; loss than air Big
media applications: communications,
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c
film dielectric trimmer capacitors can be transforming capacity :1 - 29p
main features: loss of large, small
Application : tape recorders, electronic equipment and other compensation circuit for circuit tuning capacitors of ceramic dielectric
d
power transmission capacity can be :0.3 - 22p
main features: loss of small, smaller
Applications: Precision Tuning high-frequency oscillator circuit
8, ceramic capacitors
ceramic capacitor with high dielectric constant squeezed into the tube, wafer or disc As a medium,
mulberry bags, and infiltration by firing silver plating method as the electrodes are made in ceramic. It points high and low frequency dielectric ceramic porcelain two. With a small positive temperature coefficient of capacitance of capacitors for high-stability oscillator circuit, as a whole circuit capacitors and capacitor pads. Limited to low-frequency ceramic capacitor low frequency bypass circuit for direct current or separated, or loss of stability and less demanding occasions . This capacitor should not be used in the pulse circuit, pulse voltage because they are prone to breakdown. Ceramic capacitor for high frequency circuits.
9, glass glaze capacitor (CI)
concentration for spraying by a special mixture formed into a thin film coating, then the media layer of the electrode by sintering silver monolithic 10p - 0.1u
Rated Voltage :63 - 400V
main features: good stability, low loss, high temperature (200 degrees)
applications: pulse, coupling, bypass circuit
four main characteristics of the capacitor parameters
1, nominal capacitance and tolerance
nominal capacity is a sign of the voltage on the capacitor capacity.
capacitor and the nominal effective capacitance, said capacitance deviation error said the allowed deviation range accuracy.
accuracy class and the permissible error corresponding relationship: 00 (01 )-?%, 0 (02 )-?%, Ⅰ -?%, Ⅱ -? 0%, Ⅲ -? 0%, Ⅳ - (+20% -10%), Ⅴ - (+50% -20%), Ⅵ - (+50% -30%)
General capacitors used Ⅰ, Ⅱ, Ⅲ grade, electrolytic capacitor Ⅳ, Ⅴ, Ⅵ level, according to Use selected.
2, rated voltage
rated at the lowest ambient temperature and ambient temperature can be continuously added to the maximum DC voltage capacitor RMS, the general case directly marked on the capacitor, if the resistance of the capacitor voltage exceeds pressure, capacitor breakdown, resulting in irreparable permanent damage.
3, insulation resistance
DC voltage is applied to the capacitor, and generate leakage current, the ratio is called the insulation resistance.
When the capacitor is small, depending on the surface state capacitance capacity> 0.1uf time, depending on the performance of the media, the bigger the better insulation resistance.
capacitor time constant: for the proper evaluation of large-capacity capacitors to the insulation and the introduction of a time constant, and he is equal to the capacitor insulation resistance and capacity of the product.
4, loss
capacitor electric field, internal heat in unit time is called the loss of the energy consumption. Various types of capacitors are provided in a frequency range to allow the value of the loss, capacitor loss mainly by dielectric loss,
mulberry bag, conductivity and capacitance loss of all metal parts caused by the resistance.
in the electric field under the effect of the loss of the capacitor to drain the form of derivative losses, generally small, in the alternating electric field, the capacitance and leakage losses not only lead, but also to establish the periodic polarization processes.
5, frequency
increased with frequency, capacitance of the capacitor general downward pattern.
V. capacitor capacity marked
1, direct standard method
figures and units with direct marked symbols. 0.01 microfarads as 01uF said, some capacitor with the
2, text symbols Law
symbols with numbers and words to represent a combination of regular capacity. Such as p10 that 0.1pF, 1p0 said 1pF, 6P8 that 6.8pF, 2u2 said 2.2uF.
3, Law
color or color point with a color wheel that the main parameters of the capacitor . Capacitor and resistor color code the same method.
capacitor bias glyph: +100%-0 - H, +100% -10% - R, +50% -10% - T, +30% -10% - Q, +50% -20% - S, +80% -20% - Z.