jbcapacitors blog

Jun, 1980, founded in Tainan, Taiwan to produce Plastic Film Capacitors.

Feb, 1982, started to produce Snap-in, Screw & Lug type Aluminum Electrolytic Capacitors.

Dec, 1984, established sales office and warehouse in Hong Kong Located in N.T., HK

July, 1987, moved to China and built up joint venture in Hefei, Anhui Province, China.

Dec, 1988, started production of Snap-in, Screw & Lug Aluminum Electrolytic Capacitors in China.

Aug, 1993, jb Capacitors became sole proprietorship enterprise in China.

Jun, 2003, jb Capacitors set up sales office in Dongguan, Guangdong Province, China.

March, 2005, started to produce SMD Aluminum Capacitors.

• JFA--Mylar polyester film capacitors
• JFB--Metallized polyester film capacitors
• JFL--Metallized polypropylene film capacitors
• JFG--Axial lead film capacitor
• JFV--X2 metallized polypropylene film capacitors
• JFR--Radial & Axial Polystyrene film capacitors
• JFP--High voltage metallized polypropylene cap.
• JFQ--Double sided metallized polypropylene cap.
• JFS--Motor starting film capacitors
• JFX--Premium metallized polypropylene Cap.
• JCS--85°C SMD electrolytic capacitor
• JCK--105°C SMD electrolytic capacitor

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2.Competitive prices, professional factory
3.Fast lead time
4.Strong sales & technical support, quick response

Jun, 1980, founded in Tainan, Taiwan to produce Plastic Film Capacitors.
Feb, 1982, started to produce Snap-in, Screw & Lug type Aluminum Electrolytic Capacitors.
Dec, 1984, established sales office and warehouse in Hong Kong Located in N.T., HK
July, 1987, moved to China and built up joint venture in Hefei, Anhui Province, China.
Dec, 1988, started production of Snap-in, Screw & Lug Aluminum Electrolytic Capacitors in China.
Dec, 1988, started production of Snap-in, Screw & Lug Aluminum Electrolytic Capacitors in China.
Aug, 1993, jb Capacitors became sole proprietorship enterprise in China.
Jun, 2003, jb Capacitors set up sales office in Dongguan, Guangdong Province, China.
March, 2005, started to produce SMD Aluminum Capacitors.

All capacitors have a voltage rating. This tells you how much voltage the dielectric (insulator) can withstand before allowing DC to pass between its plates. Sometimes a capacitor has a working voltage (i.e. WVDC working voltage DC) and a surge voltage. The working voltage tells you how much voltage the capacitor can withstand long term (for the normal life of the capacitor). The surge voltage is the voltage is can withstand for short periods of time. Generally, if too much voltage is applied to a capacitor, it will fail. In electrolytic capacitors, the forming voltage (voltage used to anodize the plates) and the thickness of the paper element determine the working voltage of the cap. In film type capacitors, the insulating material (polyethylene, polypropylene...) will determine the maximum working voltage.

When a DC voltage source is applied to a capacitor there is an initial surge of current, when the voltage across the terminals of the capacitor is equal to the applied voltage, the current flow stops. When the current stops flowing from the power supply to the capacitor, the capacitor is 'charged'. If the DC source is removed from the capacitor, the capacitor will retain a voltage across its terminals (it will remain charged). The capacitor can be discharged by touching the capacitor's external leads together. When using very large capacitors (1/2 farad or more) in your car, the capacitor partially discharges into the amplifier's power supply when the voltage from the alternator or battery starts to fall. Keep in mind that the discharge is only for a fraction of a second. The capacitor can not act like a battery. It only serves to fill in what would otherwise be very small dips in the supply voltage.

Capacitive reactance (symbol Xc) is a measure of a capacitor's opposition to AC (alternating current). Like resistance it is measured in ohms, Ω, but reactance is more complex than resistance because its value depends on the frequency (f) of the electrical signal passing through the capacitor as well as on the capacitance, C.

The reactance Xc is large at low frequencies and small at high frequencies. For steady DC which is zero frequency, Xc is infinite (total opposition), hence the rule that capacitors pass AC but block DC.

For example a 1µF capacitor has a reactance of 3.2kΩ for a 50Hz signal, but when the frequency is higher at 10kHz its reactance is only 16Ω.

Note: the symbol Xc is used to distinguish capacitive reactance from inductive reactance XL which is a property of inductors. The distinction is important because XL increases with frequency (the opposite of Xc) and if both XL and Xc are present in a circuit the combined reactance (X) is the difference between them.

A run capacitor is a particular type of capacitor. A run capacitor uses the charge stored in the dielectric in order to boost the electrical current providing power to an electric motor. This type of capacitor is created to maintain a charge during constant use of the motor. These capacitors are often found in devices, such as heaters, that are continuously running.

One variety of run capacitor is often used in air conditioners. This type of run capacitor is called a dual run capacitor, and uses two run capacitors for two different functions. In an air conditioner, for example, one run capacitor is used to boost the fan motor, and another is used to boost the compressor motor.

Run capacitors typically are classified at 370 or 440 volts. It is necessary to ensure that the correct rating of run capacitor is installed in an engine. If a run capacitor with an incorrect voltage rating is installed in a motor that requires a capacitor for second-phase energy, it will throw off the magnetic field. An uneven magnetic field will cause the rotor to slow in the uneven spots, which increases energy noise, as well as power consumption, and can also cause performance problems and overheating issues.

In theory, capacitors can be coupled both in series and parallel. If you need a 100MF cap and have two at 50MF, you can connect them in parallel, and that will give you 100MF (and same voltage rating as each). If you couple them in series, you get half the capacitance, and double voltage rating. But coupling electrolytic capacitors in series to get higher voltage rating must generally be discouraged. For this to work, you must be sure that the two (or more) caps share the voltage load properly; a resistor network can augment this, but if leakage currents are markedly different or the capacitors age differently, you are looking at a potential disaster, so do this only as a last resort, if at all.

An Integrated Circuit [IC] is normally decoupled using one bypass capacitor from 0.01uf to 0.1uf.Using the graph below, the 0.1uf response would result in the first dip at f1 followed by the dotted single line.

Placing a 0.01uf capacitor in parallel with the first cap also provides the second dip at f2 increasing the frequency response of the pair of caps.

The graphic above shows the benefit of placing two different value capacitors in parallel.

The impedance is reduced across a band of frequencies, adding the two nulls.

The first null is developed from the larger value capacitor, and the second null from the smaller value capacitor.

Placing a large value Tantalum capacitor next to a smaller value ceramic will cover a wide range of frequencies.

Placing two ceramic capacitors, a decade apart in value, in parallel will have the same effect but over a different frequency range.