TER electrical components Germany TER model TER price

TER electrical component is one of the earliest devices for amplifying electrical signals. The cathode electron emission part, control grid, accelerating grid, and anode (plate) leads, enclosed in a glass container (usually a glass tube), are soldered to the tube base. It uses an electric field to inject electrons into the control grid in a vacuum to modulate the signal, and obtains signal data with different parameters after amplification or feedback oscillation at the anode. Early applications included electronic products such as televisions, radios, and loudspeakers. Later, it was gradually replaced by amplifiers and integrated circuits made of semiconductor materials, but in some high-fidelity audio equipment, vacuum tubes with low noise and high stability coefficients are still used as audio power amplification devices (known in Hong Kong as "tube amplifiers").

TER electrical component principle

Inductance is the ratio of the magnetic flux in and around a conductor to the current producing this flux when alternating current flows through the conductor. When direct current flows through an inductor, only fixed magnetic field lines appear around it, which do not change with time; however, when alternating current flows through a coil, magnetic field lines that change with time appear around it. Analyzed according to Faraday's law of electromagnetic induction (magnetism generates electricity), changing magnetic field lines generate an induced electromotive force at both ends of the coil, which acts as a "new power source." When a closed loop is formed, this induced electromotive force generates an induced current. According to Lenz's law, the total magnetic field lines generated by the induced current attempt to oppose the change in the original magnetic field lines. Since the change in the original magnetic field lines originates from the change in the externally applied alternating power source, objectively, the inductor coil has the characteristic of opposing changes in current in an AC circuit. The inductor coil has a characteristic similar to inertia in mechanics, named "self-induction" in electrical engineering. Sparks often occur at the instant of opening or closing a knife switch, which is caused by the high induced electromotive force generated by self-induction.

TER electrical component principle

P-type semiconductor is formed by doping a small amount of trivalent impurity elements, such as boron, into an intrinsic semiconductor (a completely pure and structurally intact semiconductor crystal). Since a boron atom has only three valence electrons, it forms covalent bonds with surrounding silicon atoms. Due to the lack of one electron, a vacancy is created in the crystal. When electrons on adjacent covalent bonds gain energy, they may fill this vacancy, turning the boron atom into an immobile negative ion, while the covalent bond of the original silicon atom forms a hole due to the missing electron, but the entire semiconductor remains neutral. In this P-type semiconductor, conduction is mainly via holes, which are the majority carriers, while free electrons are the minority carriers. The principle of forming N-type semiconductor is similar to that of P-type. Pentavalent atoms, such as phosphorus, are doped into the intrinsic semiconductor. After doping, they form covalent bonds with silicon atoms, generating free electrons. In N-type semiconductors, electrons are the majority carriers, and holes are the minority carriers. Therefore, doping trivalent and pentavalent impurity elements into two different regions of an intrinsic semiconductor forms P-type and N-type regions. Based on the characteristics of N-type and P-type semiconductors, a concentration difference of electrons and holes appears at their junction. Electrons and holes diffuse from high-concentration regions to low-concentration regions, disrupting the electrical neutrality at the original junction. Unidirectional conductivity of the PN junction: When a forward voltage V is applied to the PN junction, the equilibrium state of the PN junction is broken under the influence of this external electric field. Holes in the P region and electrons in the N region move toward the PN junction. Holes neutralize negative ions in the P region of the PN junction, and electrons neutralize positive ions in the N region of the PN junction, thereby narrowing the PN junction. As the external electric field increases, diffusion motion further intensifies, and drift motion weakens. When the external voltage exceeds the threshold voltage, the PN junction acts as a resistor with very small resistance, meaning the PN junction is conducting.

TER electrical component applications

Metal waveguides and metal resonant cavities are widely used in the decimeter, centimeter, and longer millimeter wave bands. Since the cross-section of the waveguide and the dimensions of the resonant cavity are close to the wavelength, the small size of metal waveguides and resonant cavities makes them difficult to manufacture. It is even more impossible to apply metal waveguides or resonant cavities in the infrared or visible light bands, where wavelengths are on the micrometer scale. For this reason, dielectric waveguides and dielectric resonators have developed rapidly and gained wide application. Although the dimensions of dielectric waveguides and dielectric resonators are also on the scale comparable to the wavelength, they can be easily manufactured into tiny sizes using microfabrication techniques. For example, optical fibers and optical waveguides with cross-sectional dimensions on the micrometer scale belong to dielectric waveguides. The field in a metal waveguide can be viewed as resulting from the reciprocal reflection of plane waves between conductor surfaces, while the field in a dielectric waveguide can be viewed as resulting from the total reflection of electromagnetic waves between dielectric interfaces. Therefore, a dense medium surrounded by a sparse medium forms a dielectric waveguide. In an ideal metal waveguide, the electromagnetic field forms a standing wave transversely, and outside the waveguide boundary, it approximates an ideal conductor with no electromagnetic field. In a dielectric waveguide, the electromagnetic field forms a standing wave transversely, but an electromagnetic field still exists outside the dielectric waveguide, which decays transversely, known as an evanescent field. In a metal waveguide filled with a homogeneous medium, the TE mode and TM mode can separately satisfy the short-circuit boundary conditions of the waveguide walls, so the TE mode and TM mode can always be separated, and both can propagate in the metal waveguide. When a metal waveguide is filled with two or more media, or partially filled with dielectric, the electromagnetic field must satisfy not only the boundary conditions on the conductor walls but also the continuity conditions at the media interfaces. In the case of uniform filling with two or more media, only the mixed TE and TM HEM mode can exist. After understanding the above content, we can further explore dielectric resonators. As early as 1939, the concept and theory of dielectric resonators were proposed, but due to the lack of suitable dielectric materials, this theory remained dormant for over 20 years without practical development. By the 20s of the 60th century, the successful development of high-permittivity ceramics such as rutile ceramic (ε≈80100) brought dielectric resonators back into attention. However, the high temperature coefficient of rutile ceramic limited its practical application. In the 20s of the 70th century, barium titanate and zirconium titanate ceramics were developed. Their high permittivity, low loss, and low temperature coefficient made dielectric resonators practical. Dielectric resonators have advantages such as small size, light weight, high quality factor, and good stability. They are particularly suitable for application in microstrip circuits, microwave integrated circuits, and the millimeter wave band, receiving significant attention and developing rapidly. When the permittivity is very high, the interface between the dielectric and air approximates an open circuit, and the reflection coefficient of electromagnetic waves at the interface approaches 5. At this point, the surface of the dielectric resonator can be regarded as an open circuit wall, i.e., a magnetic wall. Thus, the dielectric resonator becomes a closed system with homogeneous boundary conditions, i.e., an equivalent open circuit wall (magnetic wall) resonant cavity.

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