Expo Technologies electrical components German Expo Technologies models Expo Technologies prices

Expo Technologies electrical components are parts of electronic components and small machines and instruments. They often consist of several parts and can be used interchangeably within similar products. The term often refers to certain parts in the electrical, radio, and instrumentation industries, and is a general term for electronic devices such as capacitors, transistors, hairsprings, and mainsprings. Common examples include diodes. Electronic components include: resistors, capacitors, inductors, potentiometers, electron tubes, heat sinks, electromechanical components, connectors, discrete semiconductor devices, electroacoustic devices, laser devices, electronic display devices, optoelectronic devices, sensors, power supplies, switches, micromotors, electronic transformers, relays, printed circuit boards, integrated circuits, various circuits, piezoelectric, crystals, quartz, ceramic magnetic materials, substrate boards for printed circuits, special materials for electronic functional processes, electronic adhesive (tape) products, electronic chemical materials and parts, etc.

Expo Technologies electrical component principles

In chemical batteries, the direct conversion of chemical energy into electrical energy results from spontaneous oxidation-reduction reactions occurring inside the battery. These reactions take place at two electrodes. The negative electrode active material consists of reducing agents with a more negative potential that are stable in the electrolyte, such as active metals like zinc, cadmium, and lead, as well as hydrogen or hydrocarbons. The positive electrode active material consists of oxidizing agents with a more positive potential that are stable in the electrolyte, such as metal oxides like manganese dioxide, lead dioxide, and nickel oxide, oxygen or air, halogens and their salts, oxyacids and their salts, etc. The electrolyte is a material with good ionic conductivity, such as aqueous solutions of acids, bases, and salts, organic or inorganic non-aqueous solutions, molten salts, or solid electrolytes. When the external circuit is open, there is a potential difference (open-circuit voltage) between the two poles, but no current flows, so the chemical energy stored in the battery is not converted into electrical energy. When the external circuit is closed, current flows through the external circuit under the influence of the potential difference between the two electrodes. Simultaneously, inside the battery, since there are no free electrons in the electrolyte, charge transfer must accompany oxidation or reduction reactions at the interface between the active materials of the two electrodes and the electrolyte, as well as mass transfer of reactants and reaction products. Charge transfer in the electrolyte is also accomplished by ion migration. Therefore, normal charge and mass transfer processes inside the battery are necessary conditions for ensuring normal electrical energy output. During charging, the direction of charge and mass transfer processes inside the battery is opposite to that during discharge; electrode reactions must be reversible to ensure the normal progress of reverse mass and charge transfer processes. Therefore, reversibility of electrode reactions is a necessary condition for constituting a storage battery. This is the basic thermodynamic relationship between battery electromotive force and battery reaction, and it is also the basic thermodynamic equation for calculating battery energy conversion efficiency. In practice, when current flows through an electrode, the electrode potential deviates from the thermodynamically balanced electrode potential; this phenomenon is called polarization. The greater the current density (current passing through a unit area of the electrode), the more severe the polarization. Polarization is one of the important causes of energy loss in batteries. There are three causes of polarization: (1) polarization caused by the resistance of various parts within the battery is called ohmic polarization; (2) polarization caused by the hindrance of the charge transfer process in the electrode-electrolyte interface layer is called activation polarization; (3) polarization caused by the sluggishness of the mass transfer process in the electrode-electrolyte interface layer is called concentration polarization. Methods to reduce polarization include increasing the electrode reaction area, reducing current density, raising the reaction temperature, and improving the catalytic activity of the electrode surface.

Expo Technologies electrical component structure

A bipolar junction transistor is made by fabricating two closely spaced PN junctions on a single semiconductor substrate. These two PN junctions divide the entire semiconductor into three parts: the middle part is the base region, and the two side parts are the emitter region and the collector region. There are two arrangement types: PNP and NPN. Corresponding electrodes are led out from the three regions, namely the base b, the emitter e, and the collector c. The PN junction between the emitter region and the base region is called the emitter junction, and the PN junction between the collector region and the base region is called the collector junction. The base region is very thin, while the emitter region is thicker and has a high impurity concentration. In PNP type transistors, the emitter region "emits" holes, whose movement direction is consistent with the current direction, so the emitter arrow points inward; in NPN type transistors, the emitter region "emits" free electrons, whose movement direction is opposite to the current direction, so the emitter arrow points outward. The direction of the emitter arrow also indicates the conduction direction of the PN junction under forward voltage. Both silicon and germanium bipolar transistors come in PNP and NPN types. Transistor package forms and pin identification: Common transistor packages fall into two main categories: metal and plastic. The pin arrangement follows certain rules. When viewed from the bottom with the three pins forming the vertices of an isosceles triangle, the order from left to right is e b c. For small and medium-power plastic transistors, orient the flat side toward you with the three pins facing downward; the order from left to right is then e b c.

Expo Technologies electrical component functions

A relay is an automatic switching component with isolation functionality, widely used in remote control, telemetry, communications, automatic control, mechatronics, and power electronic equipment, making it one of the most important control components. Relays generally have a sensing mechanism (input section) capable of responding to certain input variables (such as current, voltage, power, impedance, frequency, temperature, pressure, speed, light, etc.); an actuating mechanism (output section) capable of controlling the "on" and "off" states of the controlled circuit; and an intermediate mechanism (drive section) between the input and output sections that provides coupling isolation for the input quantity, performs functional processing, and drives the output section. As control components, relays generally serve the following functions: (1) Expanding control range: For example, when the control signal of a multi-contact relay reaches a certain value, it can simultaneously switch, disconnect, or connect multiple circuits according to different contact group configurations. (2) Amplification: For example, sensitive relays and intermediate relays can control high-power circuits using a very small control quantity. (3) Signal integration: For example, when multiple control signals are input into a multi-winding relay in a specified format, they are compared and integrated to achieve the predetermined control effect. (4) Automatic, remote control, and monitoring: For example, relays in automatic devices can form program control circuits together with other electrical appliances, thereby achieving automated operation.

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