ledvance electrical components Germany ledvance model ledvance price

ledvance electrical components are resistive devices with nonlinear voltage-current characteristics, primarily used for voltage clamping when the circuit is subjected to overvoltage, absorbing excess current to protect sensitive components. The resistive body material of a varistor is a semiconductor, making it a type of semiconductor resistor. The widely used "zinc oxide" varistors are composed of divalent zinc and hexavalent oxygen. Therefore, from a materials perspective, zinc oxide varistors are a type of "II-VI group oxide semiconductor". In Taiwan, varistors are called "surge absorbers", and are sometimes also referred to as "electric shock (surge) suppressors (absorbers)". A varistor is a voltage-limiting protection device. Utilizing the nonlinear characteristics of the varistor, when an overvoltage appears across its two terminals, the varistor can clamp the voltage to a relatively fixed value, thereby protecting the downstream circuit. The main parameters of a varistor include: varistor voltage, current handling capacity, junction capacitance, and response time. The response time of a varistor is in the ns range, faster than gas discharge tubes but slightly slower than TVS tubes; generally, this response speed meets the requirements for overvoltage protection in electronic circuits. The junction capacitance of a varistor is typically in the range of hundreds to thousands of Pf, making it unsuitable for direct application in high-frequency signal line protection in many cases. When applied in AC circuit protection, its larger junction capacitance increases leakage current, which must be fully considered in protective circuit design. Varistors have a large current handling capacity, though smaller than that of gas discharge tubes. Varistors, abbreviated as VDR, are voltage-sensitive nonlinear overvoltage protection semiconductor components.

ledvance electrical component principles

In addition to the function of converting optical signals into electrical signals like photodiodes, phototransistors also have the function of amplifying electrical signals. The appearance of a phototransistor is not much different from that of a general transistor. Generally, a phototransistor has only two leads—the emitter and the collector—with the base unconnected. The casing also has a window to allow light to enter. To increase light exposure, the base region area is made large, while the emitter region is small, so incident light is mainly absorbed by the base region. During operation, the collector junction is reverse-biased, and the emitter junction is forward-biased. In the absence of light, the current flowing through the transistor is the dark current Iceo = (1 + β) Icbo (very small), which is even smaller than the penetration current of general transistors; when illuminated, a large number of electron-hole pairs are generated, causing the base current Ib to increase. The current flowing through the transistor at this moment is called photocurrent, and the emitter current Ie = (8 + β) Ib. It can be seen that phototransistors have higher sensitivity than photodiodes.

ledvance electrical component parameters

The main parameters of potentiometers include nominal resistance, rated power, resolution, sliding noise, resistance variation characteristic, wear resistance, zero-position resistance, and temperature coefficient. 1. Rated power: The maximum power allowed to be dissipated across the two fixed terminals of a potentiometer is its rated power. Note that the rated power is not equal to the power between the center tap and the fixed terminal. The rated power of a potentiometer refers to the maximum power allowed to be consumed under long-term continuous load at the specified rated temperature, when the atmospheric pressure is 87~107kPa. 2. Nominal resistance: The nominal resistance marked on the product, with series similar to those of resistors. 3. Tolerance class: The error range between the measured resistance and the nominal resistance allows for 20%, 10%, 5%, 2%, 1% errors depending on the precision class. The precision of precision potentiometers can reach 0.1%. 11. Resistance variation law: Refers to the relationship between resistance change and the rotation angle (or sliding travel) of the wiper contact. This relationship can take any functional form, commonly linear, logarithmic, and reverse logarithmic (exponential). In use, linear potentiometers are suitable as voltage dividers; reverse logarithmic (exponential) potentiometers are suitable as volume controls in radios, recorders, phonographs, and televisions. If a replacement of the same type is not found during maintenance, a linear type can be used as a substitute, but a logarithmic type should not be used. Logarithmic potentiometers are only suitable for tone control, etc.

ledvance electrical component functions

In DC circuits, capacitors act as open circuits. A capacitor is a component capable of storing electric charge and is one of the most commonly used electronic components. Starting with the structure of a capacitor, the simplest capacitor consists of two end plates and an insulating dielectric medium in between (including air). After being energized, the plates become charged, forming a voltage (potential difference). However, due to the insulating material in between, the entire capacitor does not conduct electricity. However, this situation holds under the premise that the critical voltage (breakdown voltage) of the capacitor is not exceeded. We know that any material is relatively insulating; when the voltage across a material increases to a certain level, the material can conduct electricity. We call this voltage the breakdown voltage. Capacitors are no exception; once a capacitor breaks down, it is no longer an insulator. However, at the secondary school level, such voltages are not seen in circuits, so they operate below the breakdown voltage and can be regarded as insulators. However, in AC circuits, because the direction of current changes according to a certain functional relationship over time, and the charging and discharging process of a capacitor takes time, a changing electric field is formed between the plates, and this electric field is also a function that changes over time. In fact, current passes through the capacitor in the form of an electric field.

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