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Passive Components

These parts are basic electronic components, they are called passive, because they don’t amplify, generate or control. They do their one function.


This component is used mainly in storing electrical energy and protecting the circuit against voltage spikes. Basic capacitors are made of two parallel plates separated by an insulating material called a dielectric. Capacitors store electrical charge, conducting alternating current (AC) and blocking voltages of direct current (DC). Fixed capacitor is basic one, polarized capacitor has polarized terminals and variable capacitor has adjustable capacity. The unit of capacitance is the Farad (F).


Crystals and Oscillators

These parts are used for timing and controlling frequencies. Oscillator produces periodic, oscillating signals or alternating current (AC) signal in waveform while it’s being powered by direct current (DC). We can find them in anything that requires a work with waveform (cellphones, radios, televisions, radars, transmitters, …). Crystal oscilator is a bit more specific, it has a crystal, usually made from quartz, that creates frequencies. They are highly accurate, we can find them in previous mentioned devices, but also in the integrated circuits.


EMI / RFI Components (Electromagnetic Interference/Radio Frequency Interference)

Electromagnetic waves can have a negative effect on the electronic devices, so purpose of these components is to avert negative effects caused by the electromagnetic waves, the basically work as filters.


Inductors (coils, chokes)

Component of two terminals which stores energy in the magnatic field, when current flows through. It can be used as energy storage, filter or in timing systems. It’s made of wound up wire around an electromagnetic coil. The unit of inductance is Henry (H).



We can see these two termal parts in any device, it reduces current which then also affects voltage. The reletionship between resistence, current and voltage is called „Ohm’s law“. There’s also variable resistors, these have adjustable resistence. The unit of resistance is Ohms (Ω).



The purpose of this component is to pass on electrical energy from one curcuit to another or more. Its’s made of magnetic core and two coils, each wire is wound up on the opposite side of the core, it’s called primary and secondary winding. Current in one coil of the transformer produces a magnetic flux, which in turn, induces a electromotive force across a second coil wound around the same core. Transformers are capable to increase or decrease the voltage and current levels without changing the frequency.