Trusted Name In Electronics Components

Beiträge vom May, 2011

photo diodes

Tuesday, 31. May 2011 5:25

A photodiode responds to incident electromagnetic radiation by converting the radiation into electrical energy, thereby enabling measurement of the intensity of the incident radiation. A photodiode comprises photoconductivity cell and a junction diode, and is commonly used in photoelectric products, such as cameras and photosensors of scanners. A light-induced current of the photodiode represents a signal, whereas a current present in an absence of light represents noise. The photodiode processes signal data by using a magnitude of a signal-to-noise ratio. Avalanche diodes are based on reverse-biased p-n junction diodes operated at voltages above the breakdown voltage. In general, an avalanche photodiode is used for converting an input optical signal to an electrical signal, while amplifying the input signal through the avalanche effect by the injection of carriers into an area applied with a high electrical field. Avalanche photodiodes are widely employed in high-speed communication systems. Avalanche diodes are preferred over many other candidate photodetectors, including PIN diodes, particularly due to their high internal gain characteristics and improved signal-to-noise ratio. A PIN photodiode comprises a P-type semiconductor, a N-type semiconductor, and an intrinsic semiconductor layer interposed there-between. The PIN photodiode is typically used as a light-receiving element for converting an optical signal into an electric signal as it possessesexcellent characteristics in converting incident photons into electrons. As a photodiode used in a receiving module of an optical communication system, there are waveguide photodiode and an evanescently coupled photodiode.

Thema: Leds | Kommentare (0) | Autor:

Level switches

Monday, 30. May 2011 1:53

Liquid level sensing devices are often used to indicate the level of liquid in a vessel or other container and/or to operate flow control devices that control the liquid level. The level detection is based on different principles. There are known mechanical, electromechanical and hydrostatic level switches, ultrasonic level switches, capacitive and conductive level switches, microwave level switches, optical and radiometric level switches. Mechanical and electromechanical level switches are suitable for liquids only. Mechanical and electromechanical level switches usually incorporate a float buoy for sensing the fluid level, the float buoy being operatively connected to a switch device. The electrical switch is actuated upon physical movement of the portion of the float switch device containing the electrical switch or upon physical movement of another portion of the float switch device. A capacitance point level switch is operable to sense a specific level of the material in the vessel and provide a discrete output, such as with a relay contact, when the material is at a sufficient level to cause the capacitance between the probe and the reference to exceed a reference value. The capacity of the measuring capacitor within a sensor varies according to the surface level displacement of the material contained in a tank.

Thema: Switches | Kommentare (0) | Autor:

about PCBs

Friday, 27. May 2011 3:45

A printed circuit board (PCB) is a circuit board fabricated by densely mounting a plurality of parts on a plate made of phenol resin or epoxy resin and densely forming curtailed circuits on the surface of the plate to connect the respective parts to each other. A printed circuit board is typically produced by alternately stacking a plurality of substrates with conductive circuits formed thereon and prepreg sheets, bonding them under heat and pressure, forming holes to allow electrical parts to be mounted on the insulating plate, and plating them with copper or other metallic materials to provide an electrical connection between the surface and inner layers. Printed circuit boards have a variety of electric or electronic parts soldered to their circuit patterns which are formed by labyrinth-like copper foils, each having electric or electronic parts soldered to lands with their terminals inserted in the terminal holes, which are made in the lands. Printed circuit boards are classified into single-sided PCBs, double-sided PCBs and multi-layer PCBs depending the number of wiring circuit surfaces. A multi-layer PCB provides a plurality of electrically conductive layers separated by insulating dielectric layers. A typical multi-layer PCB includes many layers of copper, with each layer of copper separated by a dielectric material. Multi-layer printed circuit boards are commonly used in electronic devices to connect electronic components such as integrated circuits to one another. Printed circuit boards used in various types of data processing systems (especially in computers) are typically mounted within a plastic or sheet metal housing structure, and are conventionally referred to as motherboards and daughterboards. A motherboard is the main circuit board containing the primary components of a computer system. A daughterboard is a circuit board that attaches to a motherboard, or other type board, and provide additional or enhanced functions to a motherboard.

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Rocker switches

Thursday, 26. May 2011 3:49

A rocker switch is a device having a plurality of terminals and means operated by a rocker for making and breaking electrical connections between pairs of those terminals. A rocker switch includes a button that is mounted to a case to pivot about an axis. A spring is typically placed in contact with the button to exert a biasing force that will maintain the button in one or more of the stable positions. The plunger operates a rocker actuator by a force exerted from the spring. The spring also supplies the force that causes the switch to toggle from one stable position to another. In general, the rocker switch is constructed such that its switch components or parts are housed in a square or rectangular housing the top of which is open and an operation button is mounted at the opening space of the box at the top thereof such that it can be moved for seesaw movement. The rocker switches are used in various kinds of OA machines, amusement and game machines, measurement instruments, and medical instruments.

Thema: Switches | Kommentare (0) | Autor:

toggle switches

Wednesday, 25. May 2011 5:18

A toggle switch is a switching device comprising a plurality of terminals and means operated by a projecting leve for making and breaking electrical connections between pairs of those terminals. Toggle switches of various types have long been used to control power in domestic, commercial, industrial, and military applications for operating various electrical devices and equipment. Toggle switches typically are manufactured with a dielectric housing that contains electrical contacts and is fitted with a manually operable handle to switch power to externally mounted terminals. Toggle switches typically provide a manually accessible member which has metastability in a first position and a second position. A toggle switch includes a toggle lever that is mounted to a cover or housing so as to pivot about an axis or the like. A spring is placed in contact with the toggle lever to exert a biasing force to maintain the toggle lever in one or more stable positions, in addition to maintaining or assisting in the maintenance of a force on electrical contacts that are being switched into contact.

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about push button switches

Monday, 23. May 2011 6:26

A push button switch is used to either close or open an electrical circuit depending on the application. Push button switches are used in various applications such as industrial equipment control handles, outdoor controls, mobile communication terminals, and medical equipment, and etc. Push button switches generally include a push button disposed within a housing. The push button may be depressed to cause movement of the push button relative to the housing for directly or indirectly changing the state of an electrical contact to open or close the contact. Also included in a pushbutton switch may be an actuator, driver, or plunger of some type that is situated within a switch housing having at least two contacts in communication with an electrical circuit within which the switch is incorporated. Typical actuators used for contact switches include spring loaded force cap actuators that reciprocate within a sleeve disposed within the canister. The actuator is typically coupled to the movement of the cap assembly, such that the actuator translates in a direction that is parallel with the cap. A push button switch for a data input unit for a mobile communication device such as a cellular phone, a key board for a personal computer or the like is generally constructed by mounting a cover member directly on a circuit board. Printed circuit board (PCB) mounted pushbutton switches are an inexpensive means of providing an operator interface on industrial control products. In such push button switches, a substrate which includes a plurality of movable sections is formed of a rubber elastomer. The key top is formed on a top surface thereof with a figure, a character or the like by printing, to thereby provide a cover member. Push button switches incorporating lighted displays have been used in a variety of applications. Such switches are typically comprised of a pushbutton, an opaque legend plate, and a back light to illuminate the legend plate.

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Electrical switches

Friday, 20. May 2011 7:50

Electrical switches are devices utilized to manually control electric current flow. Manually operated switches include an actuator used to cause making/breaking action of switch contacts to energize or de-energize one or more electrical circuits associated with the contacts. In addition to switching electrical signals responsive to physical actuation of the switch, electrical switches may include actuation indication including tactile feedback or audible feedback. Switches are available that are equipped with lamps used for helping people find the switches in the dark. There are several different types of light switches. Common switch types include rocker, toggle, push button, rotary, keylock, slide, snap action and reed switches. Switches are highly varied based on their intended utility. In electromechanical systems, switches provide the function of making and breaking electrical contacts and consequently electrical circuits. Switches responsive to fluid levels have utilized a variety of approaches for opening and closing an electrical circuit. Switches have found particular use in industrial control systems, where it is often desirable to monitor conditions so that appropriate actions may be taken in response to the monitored conditions.

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Thursday, 19. May 2011 2:03

Thermistors (thermally sensitive resistors), are ceramic semiconductors which exhibit large changes in electrical resistance with corresponding changes in temperature. The thermistor may employ NTC (negative temperature coefficient) material whose resistance is decreased as temperature increases or PTC (positive temperature coefficient) material whose resistance is increased as temperature increases. The thermistor is used to provide a signal voltage that changes as a function of the change in resistance of the temperature sensor. The most important characteristics of thermistors are an extremely high temperature coefficient of resistance and precise resistance versus temperature characteristics. The sensitivity to temperature change can result in a thermistor resistance change of 10 million to one over an operating temperature range. Because of their sensitivity, accuracy, and stability, thermistors are generally accepted to be the most advantageous sensor for many applications including temperature measurement, compensation, and control. PTC (positive temperature coefficient) thermistors are well known devices which have been employed in electronic circuits for over current protection and for thermal sensing. The electrical resistivity of a positive temperature coefficient (PTC) thermistor increases with increase in temperature. PTC thermistors switch from a low resistance to a high resistance state at a specific temperature. Organic PTC (positive temperature coefficient) thermistors made of an organic thermistor material are coming to be used as circuit protection units for suppressing overcurrents. Such organic PTC thermistor devices make use of an organic thermistor material obtained by dispersing carbon in a resin material such as polyethylene to provide a positive temperature characteristic. In NTC thermistors, their resistivity decreases approximately exponentially with temperature. NTC thermistors used for temperature measurement and compensation are usually made from various compositions including the oxides of manganese, nickel, cobalt, copper, iron, and other metals to form a ceramic semiconductor material.

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Chip resistors

Wednesday, 18. May 2011 2:39

The integrated circuit (IC) chips in modern electronic devices include circuits, such as mixed signal circuits, RF circuits, and power amplifier circuits, that require accurate and stable voltages to operate properly. To obtain stable voltages, the circuits in an IC chip, in turn, require components, such as resistors, that remain stable under diverse operating conditions. Recently, a demand for miniaturization or dimensional reduction of electronic devices is more and more increasing, and as a result, very small-sized chip electronic components are increasingly employed as electronic components. Under this circumstance, high precision chip resistors have been demanded as alternatives to conventionally used trimming volumes. In particular, the demand for chip resistors having a low resistance and a small temperature coefficient of resistance used in a power supply circuit has been increased. A typical chip resistor may include a small, rectangular supporting substrate on which a resistor layer having a required resistance is formed together with two terminal electrodes connected to the resistor layer. For protection of the resistor layer, a protective coating is formed on the substrate to cover the resistor layer. Chip resistors are generally produced by forming a resistive layer on the surface of an insulating substrate, providing electrodes at both ends of the resistive layer, and forming one or more protective films on the surface of the resistive layer.

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Monday, 16. May 2011 2:46

Ultracapacitors,supercapacitors or electrochemical capacitors, are energy storage devices which can store more energy than traditional capacitors and discharge this energy at higher rates than rechargeable batteries. Ultracapacitors are sometimes referred to as “double layer capacitors”, and are notable for their ability to store more energy per unit weight and volume than conventional capacitors. They are also able to deliver the stored energy at a higher power level than is possible with other electrochemical devices, such as batteries. Ultracapacitors are attractive because they can be connected together, similar to batteries, for high-voltage applications; have an extended life of hundreds of thousands of charge/discharge cycles. Electrochemical capacitors are prospective in potential applications in emerging technology areas that require electric power in the form of pulses. Examples of such applications include digital communication devices that require power pulses in the millisecond range, and traction power systems in an electric vehicle where the high power demand can last from seconds up to minutes.Ultracapacitors have a low equivalent internal series resistance that allows an ultracapacitor pack to accept and supply much higher power than similar battery packs. Ultracapacitors consist of two porous electrodes that are isolated from electrical contact by a porous separator. Both the separator and the electrodes are impregnated with an electrolytic solution. This allows ionic current to flow between the electrodes while preventing electrical current from shorting the cell. On the back of each of these active electrodes is a current collecting plate. In operation, an electrode potential, or voltage, exists across the electrodes in the ultracapacitor. Ionic current can then flow as anions are discharged from the surface of the positive electrode where they were stored. In similar fashion, cations are discharged from the surface of the negative electrode.

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