Voltage and Frequency Dependence on Resistors

Posted by Tomáš Zedníček
On March 6, 2021
0

Voltage Dependence If we apply a voltage on a resistor it’s resistance will drop slightly in certain types. Therefore the resistance change is negative. The change per volt of applied voltage is called voltage coefficient, VC, and is expressed in %/V or better, μV/V. The coefficient is determined not only by the resistive material but also by the dimensions, i.e., the electrical field strength, and the time of applied voltage. Thus, MIL-STD-202, Method 309 prescribes measurements when the voltage is applied intermittently for less than 0.5 seconds.

ABC of CLR, EEE Components, PASSIVES

Permeability concept in Inductors

Posted by Tomáš Zedníček
On March 4, 2021
0

Permeability describes an important effect in ferromagnetic materials. If a ferromagnetic material is placed in a magnetic field, it is observed that the magnetic flux becomes concentrated in this material. Analogous to electric resistance, the ferromagnetic material presents a good conductor for the field lines. Permeability may therefore be described as a magnetic conducting or penetrating property.

ABC of CLR, EEE Components, PASSIVES

Paper Capacitors

Posted by Tomáš Zedníček
On January 27, 2021
0

Because paper is porous it has to be impregnated in order to prevent corona effects and flash-overs. It is done by use of melted wax or different kinds of oils, among other things mineral and silicone oils. The oils increase the tensional stability but decrease to a certain extent the εr. A fibrous paper has a εr ≈ 6.6 and the mineral oil ≈ 2.3 which gives the impregnated winding a εr varying between 3.1 and 4.5. The differences depend above all on the winding pressure produced by the tensile force during winding.

ABC of CLR, EEE Components, PASSIVES

Non-Wirewound Resistors: Film, Foil & Metal Oxide

Posted by Tomáš Zedníček
On January 6, 2021
1

Introduction to Film Resistors Film resistors are built either on cylindrical rods or on planar substrates. Usually, the material in the rods and substrates is ceramic in the state of aluminum oxide (alumina), but glass may occur. Hollow cores exist but are more and more abandoned when sizes are becoming smaller. This design suffers also from drawbacks: the construction is more fragile and the heat dissipation is poorer than that of a solid core.

ABC of CLR, EEE Components, INSPECTION, ELECTRICAL & VERIFICATION, PASSIVES, TESTING

Toroidal Power Inductors

Posted by doEEEt Media Group
On December 30, 2020
0

The selection of cores and windings of storage chokes are optimized for use in switching converters and DC-DC converters

ABC of CLR, EEE Components, ENDURANCE, ENVIRONMENTAL & RADIATION, PASSIVES, TESTING

Current Compensated Chokes

Posted by doEEEt Media Group
On December 30, 2020
0

The effect of current-compensated chokes on coupled interference is used for data and signal lines. They are often the only option to avoid the interference suppression component affecting the useful signal

ABC of CLR, EEE Components, INSPECTION, ELECTRICAL & VERIFICATION, PASSIVES, TESTING

Coil with Ferrite Inductors

Posted by doEEEt Media Group
On December 30, 2020
0

SMD-Multilayer Inductor, Power Multilayer Inductors and SMD – Wire Wound Inductor /SMD RF Inductor are described in this post

ABC of CLR, EEE Components, INSPECTION, ELECTRICAL & VERIFICATION, PASSIVES, TESTING

Transformer Calculation and Applications

Posted by doEEEt Media Group
On December 30, 2020
0

Transformers can be used for various tasks: Isolation, Voltage transformation, Current transformation, Impedance matching

ABC of CLR, EEE Components, PASSIVES

Resistivity, Rth and TCR of Resistors

Posted by Tomáš Zedníček
On December 6, 2020
0

Depending on what units we express l and A in we get different units of r. A common way is by expressing l in m(eter) and A in mm2 r then gets the unit W´mm2/m. If we instead choose l in m and A in m2, the unit for r will be W´mm2/m, which usually is transformed to Wm. That unit often is used for non-metallic materials. If we know the value of r expressed in W´mm2/m, that value has to be multiplied by the factor 10-6 to give the value in Wm. Thus, 10-6 x W×mm2/m = 1 Wm.

ABC of CLR, EEE Components, PASSIVES

Understanding the Ampère’s Law and Magnetic Fields in Inductors

Posted by Tomáš Zedníček
On December 5, 2020
0

Magnetism: The basis for understanding inductors is provided by magnetism and a few fundamental electromagnetic field laws, revealing clear and fundamental knowledge of inductors and ferrites. The most important phenomena and laws will still perhaps be there from physics lessons:

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