unold electrical components Germany unold model unold price

unold electrical components are one of the earliest types of electrical signal amplification devices. The cathode electron emission part, control grid, accelerating grid, and anode (plate) leads, enclosed in a glass container (usually a glass tube), are welded to the tube base. An electric field is used to inject electrons into the control grid in a vacuum to modulate the signal, and different parameter signal data after signal amplification or feedback oscillation are obtained at the anode. Early applications included electronic products such as televisions, radios, and amplifiers. Later, they were gradually replaced by amplifiers and integrated circuits made from 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 (in Hong Kong, vacuum tube power amplifiers are referred to as "tube amplifiers").

unold electrical component composition

1. A general fuse consists of three parts: First, the fusible element, which is the core of the fuse and serves to cut off the current when it melts. For fuses of the same type and specification, the fusible element must have the same material, identical geometric dimensions, as small and consistent resistance as possible, and most importantly, consistent fusing characteristics. Household fuses are commonly made of lead-antimony alloy. Second, the electrode part, usually consisting of two electrodes, is an important component connecting the fusible element to the circuit. It must have good electrical conductivity and should not produce significant installation contact resistance. Third, the support part. Since the fusible element of a fuse is generally thin and flexible, the support serves to fix the fusible element and make the three parts a rigid whole for easy installation and use. It must have good mechanical strength, insulation, heat resistance, and flame retardancy, and should not exhibit phenomena such as breaking, deformation, combustion, or short circuits during use. 2. Arc extinguishing device: Fuses used in power circuits and high-power equipment not only have the three parts of a general fuse but also include an arc extinguishing device. This is because the circuits protected by such fuses not only have larger operating currents, but also have high voltage across the terminals when the fusible element melts. Often, the fusible element may have melted (fused) or even vaporized, but the current has not been cut off. The reason is that arcing occurs between the two electrodes of the fuse under the action of voltage and current at the moment of fusing. This arc extinguishing device must have strong insulation and good thermal conductivity, and be negatively charged. Quartz sand is a commonly used arc extinguishing material. 12. Fusing indication device: Some fuses have a fusing indication device. Its function is to cause a certain change in appearance after the fuse operates (melts), making it easy for maintenance personnel to detect, such as lighting up, changing color, or popping out a solid indicator.

unold electrical component principle

Inductance is the ratio of the magnetic flux in and around a conductor to the current producing this magnetic flux when alternating current passes through the conductor. When direct current passes through an inductor, only fixed magnetic field lines appear around it, which do not change with time; however, when alternating current passes through a coil, magnetic field lines that change with time appear around it. Analyzing according to Faraday's law of electromagnetic induction—magnetism generating electricity—a changing magnetic field line produces 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 produced by the induced current strive 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 external alternating power source, objectively, the inductor coil has the characteristic of opposing changes in current in an AC circuit. The inductor coil has characteristics 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 the self-induction phenomenon.

unold electrical component function

The self-induced electromotive force in an inductor coil always opposes the change in current within the coil. The inductor coil impedes alternating current, and the magnitude of this impedance is called inductive reactance xl, measured in ohms. Its relationship with inductance l and AC frequency f is xl=2πfl. Inductors can be mainly classified into high-frequency choke coils and low-frequency choke coils. An inductor coil connected in parallel with a capacitor can form an lc tuning circuit. That is, when the natural oscillation frequency f0 of the circuit equals the frequency f of the non-AC signal, the inductive reactance and capacitive reactance of the loop are equal, causing electromagnetic energy to oscillate back and forth between the inductor and capacitor. This is the resonance phenomenon of the lc loop. At resonance, the inductive reactance and capacitive reactance of the circuit are equal in value but opposite in direction, resulting in minimum inductive reactance for the total loop current and maximum current (referring to AC signals where f="f4"). The lc resonant circuit has the function of frequency selection, capable of selecting AC signals of a specific frequency f.

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