## Why not change the units to be better sizes in Electronics?

It might seem a good idea to make the farad (F) much smaller to avoid having to use µF, nF and pF, but if we did this most of the equations in electronics would have to have factors of 1000000 or more included as well as the quantities. Overall it is much better to have the units with their present sizes which are defined logically from the equations.

In fact if you use an equation frequently you can use special sets of prefixed units which are more convenient...

For example: Ohm's Law, V = I × R
the standard units are volt (V), amp (A) and ohm (Ω),
but you could use volt (V), milliamp (mA) and kilo-ohm (kΩ) if you prefer.
Take care though, you must never mix sets of units: using V, A and kΩ in Ohm's Law would give you wrong values.

## Also you need to know the Units in Electronics

The unit (and unit symbol) which is used to measure each quantity. For example: Charge is measured in coulombs and the symbol for a coulomb is C.

Some of the units have a convenient size for electronics, but most are either too large or too small to be used directly so they are used with the prefixes shown in the second table. The prefixes make the unit larger or smaller by the value shown.

Some examples:
25 mA = 25 × 10-3× 0.001 A = 0.025 A
47µF = 47 × 10-6× 0.000 001 F = 0.000 047 F
270kΩ = 270 × 103 Ω= 270 × 1000 Ω= 270 000 Ω F = 47 A = 25

PrefixPrefix SymbolValue
millim10-3=0.001
microµ10-6=0.000 001
nanon10-9=0.000 000 001
picop10-12=0.000 000 000 001
kilok103=1000
megaM106=1000 000
gigaG109=1000 000 000
teraT1012=1000 000 000 000

## jb capacitors tell you the Quantities in Electronics

The table shows electrical quantities which are used in electronics.

The relationship between quantities can be written using words or symbols (letters), but symbols are normally used because they are much shorter; for example V is used for voltage, I for current and R for resistance:

As a word equation:

voltage = current×resistance

The same equation using symbols: V=I×R

To prevent confusion we normally use the same symbol (letter) for each quantity and these symbols.

Please click on the quantities in the table for further information.

Quantity Usual Symbol Unit Unit Symbol
Voltage V volt V
Current I amp* A
Charge Q coulomb C
Resistance R ohm Ω
Capacitance C farad F
Inductance L henry H
Reactance X ohm Ω
Impedance Z ohm Ω
Power P watt W
Energy E joule J
Time t second s
Frequency f hertz Hz
* strictly the unit is ampere, but this is almost always shortened to amp.

## SMD Electrolytic capacitors of jb Capacitors

Electrolytic capacitors are now being used increasingly in SMD designs. Their very high levels of capacitance combined with their low cost make them particularly useful in many areas.

Often SMD electrolytic capacitors are marked with the value and working voltage. There are two basic methods used. One is to include their value in microfarads (m F), and another is to use a code. Using the first method a marking of 33 6V would indicate a 33 mF capacitor with a working voltage of 6 volts. An alternative code system employs a letter followed by three figures. The letter indicates the working voltage as defined in the table below and the three figures indicate the capacitance on picofarads. As with many other marking systems the first two figures give the significant figures and the third, the multiplier. In this case a marking of G106 would indicate a working voltage of 4 volts and a capacitance of 10 times 10^6 picofarads. This works out to be 10 mF.

Letter Voltage
e 2.5
G 4
J 6.3
A 10
C 16
D 20
E 25
V 35
H 50

jbcapacitorsis thespecialty manufacturer of the SMD Electrolytic capacitor.Ourjb capacitorshave JCS - 2000H at 85°C SMD Aluminum Electrolytic Capacitor and JCK - 1000H at 105°C SMD Aluminum Electrolytic Capacitor.

JCK

JCS

## Know more about Electronic Component

An electronic component is a basic electronic element usually packaged in a discrete form with two or more connecting leads or metallic pads. Components are intended to be connected together, usually by soldering to a printed circuit board, to create an electronic circuit with a particular function (for example an amplifier, radio receiver, or oscillator). Components may be packaged singly (resistor, capacitor, transistor, diode etc.) or in more or less complex groups as integrated circuits (operational amplifier, resistor array, logic gate etc.)

## News for jb Capacitors Company Exhibit at Electronica 2010 in Munich

On Nov 9th~12th,2010, jb Capacitors Company exhibit at Electronica 2010 in Munich, Germany.
Booth No. is B6.437/10.

Below you can see our green booth photos. Our booth are very popular, many customers visited our booth with great pleasure.
Our exhibition are very successful.

On the show, we exhibit below, also welcome to contact our sales if you are interested in our leafletes, sample kits, and green bags, and samples.

1. jb Capacitors green leaflets
2. jb Capacitors green sample kits
3. jb Capacitors green bags
4. jb Capacitors samples: including below different series of samples:

JFB - Metallized Polyester Film Capacitor
0.1uF 250V +/-10% P:10mm Bulk RoHS
0.047uF 400V +/-10% P:10mm Bulk RoHS
0.47uF 250V +/-10% P:15mm Bulk RoHS

JFD - Box Type Metallized Polyester Film Capacitor
0.1uF 250V +/-10% P:15mm Bulk RoHS

JFJ - Mini Box Stacked Metallized Polyester Film Capacitor
0.047uF/63V +/-5% P:5mm Bulk RoHS
0.15uF 100V +/-5% P: 5mm Bulk RoHS
0.22uF 63V +/-5% P:5mm Bulk RoHS
0.1uF 100V +/-5% P:5mm 7.2*6.5*2.5mm Bulk RoHS

JFL - Metallized Polypropylene Film Capacitor
0.33uF 100V +/-10% P:15mm Bulk RoHS

Axial Metallized Polyester & Polypropylene Film Capacitor
JFGA 0.22uF 100V +/-10% 15*7MM Bulk RoHS
JFGA 0.33uF 630VDC +/-10% Bulk RoHS

JFX - Premium Met Polypropylene Film Capacitors – Axial
4.7uF 250V +/-5% Bulk RoHS

JFN - X2 Metallized Polypropylene Film Capacitor
0.1uF 275VAC +/-10% P:15mm Bulk RoHS
0.15uF 275VAC +/-10% P:15mm Bulk RoHS
0.22uF 275VAC +/-10% P:15mm Bulk RoHS
0.1uF 275VAC +/-10% P:10mm Bulk RoHS
0.33uF 275VAC +/-10% P:15mm Bulk RoHS
0.47uF 275VAC +/-10% P:22.5mm Bulk RoHS
0.068uF 275VAC +/-10% P:10mm Bulk RoHS

JFO - X2 Metallized Polypropylene Film Capacitor
0.047uF 275VAC +/-10% P:10mm Bulk RoHS
0.1uF 275VAC +/-10% P:10mm Bulk RoHS
0.33uF 275VAC +/-10% P:15mm Bulk RoHS
0.47uF 275VAC +/-10% P:15mm Bulk RoHS

JFP - High Voltage Met Polypropylene Film Capacitor
470pF 2000V +/-10% P:15mm Bulk RoHS

JCS--SMD - Aluminum Electrolytic Capacitors
10uF 50V +/-20% 6.3x5.4mm 2000h at 85°C
22uF 16V +/-20% Size:4*5.4mm 2000h at 85°C

JNE--Snap in Aluminum Electrolytic Capacitors
470uF 200V +/-20% 2000h 25x30mm P:10mm 2000h at 105°C Bulk RoHS

JMJ--Screw terminals Aluminum Electrolytic Capacitors
22000uF 63V +/-20% Size: 51x80mm 2000h at 85°C Bulk RoHS

## jb Summary of Capacitor Types

The table below gives and overview of the main characteristics of the various types of capacitor.

Capacitor types Capacitance range Accuracy Temperature stability Leakage Comments
Electrolytic 0.1 µF - ~1 F V poor V poor Poor Polarised capacitor - widely used in power supplies for smoothing, and bypass where accuracy, etc is not required.
Ceramic 10 pF - 1 µF Variable Variable Average Exact performanceof capacitor depends to a large extent on the ceramic used.
Tantalum 0.1 µF - 500 µF Poor Poor Poor Polarised capacitor - very high capacitance density.
Silver mica 1 pF - 3000 pF Good Good Good Rather expensive and large - not widely used these days except when small value accurate capacitors are needed.
Polyester (Mylar) 0.001 µF - 50 µF Good Poor Good Inexpensive, and popular for non-demanding applications.
Polystyrene 10 pF - 1 µF V good Good V good High quality, often used in filters and the like where accuracy is needed.
Polycarbonate 100 pF - 20 µF V good V good Good Used in many high tolerance and hash environmental conditions. Supply now restricted.
Polypropylene 100pF - 50 µF V good Good V good High performance and low dielectric absorption.
Teflon 100 pF - 1 µF V good V v good V v good High performance - lowest dielectric absorption.
Glass 10 pF - 1000 pF Good Good V good Excellent for very harsh environments while offering good stability. Very expensive.
Porcelain 100 pF - 0.1 µF Good Good Good Good long term stability
Vacuum and air 1 pF - 10 000 pF       Often used as variable capacitors in transmitters as a result of their very high voltage capability.

Welcome to visit our jb capacitors website http://www.jbcapacitors.com/ to search your interestedcapacitors.

## Units of capacitance

It is necessary to quantify a capacitor in terms of its ability to store charge. The basic unit of capacitance is the Farad, named after Michael Faraday.

The definition of A Farad is: A capacitor has a capacitance of one Farad when a potential difference of one volt will charge it with one coulomb of electricity (i.e. one Amp for one second).

In view of the fact that a capacitor with a capacitance of one Farad is too large for most electronics applications, components with much smaller values of capacitance are normally used. Three prefixes (multipliers) are used, µ (micro), n (nano) and p (pico):

Prefix Multiplier
µ 10-6 (millionth) 1000000µF = 1F
n 10-9 (thousand-millionth) 1000nF = 1µF
p 10-12 (million-millionth) 1000pF = 1nF

## jb motor starting capacitors

Start capacitors briefly increase motor starting torque and allow a motor to be cycled on and off rapidly. Start capacitors have ratings above 70 microfarads (µF), with three major voltage classifications: 125 V, 250 V, and 330 V. A start capacitor stays energized long enough to rapidly bring the motor to 3/4 of full speed and is then taken out of the circuit, such as by a centrifugal switch that releases when rotating at or around that speed.

Examples of motor capacitors are: a 35 µF, at 370 V, run capacitor, or an 88–108 µF at 250 V start capacitor.

jb have the motor starting capacitors of capacitance range 1uF~20uF(JFS-A~D、JFS-5~7、JFS-9) 1uF~100uF(JFS-11~18).

## What is Capacitance ?

The capacitance of certain capacitors decreases as the component ages. In ceramic capacitors, this is caused by degradation of the dielectric. The type of dielectric and the ambient operating and storage temperatures are the most significant aging factors, while the operating voltage has a smaller effect.

The aging process may be reversed by heating the component above the Curie point. Aging is fastest near the beginning of life of the component, and the device stabilizes over time,electrolytic capacitors age as the electrolyte evaporates. In contrast with ceramic capacitors, this occurs towards the end of life of the component.

Our jb capacitors has various capacitance.Such as our JFA-Mylar Polyester Film Capacitors, capacitance range from 0.001 to 0.47μF.