Passive electronic componens are indispensable components in electrical circuits. A simple electric circuit consists of a source (such as a battery),wires as conducting medium and a load (such as a light bulb). The battery provides required energy for flow of electrons, to the light bulb.
As mentioned above in the introduction, a circuit is an interconnection of elements. These elements are classified into active or passive elements, based on their capability to generate energy.
I. Distinguish the term of active and passive components
1.1. Active components
Active Elements are those which can generate energy. Examples include batteries, generators, operational amplifiers and diodes. Note that in an electrical circuit, the source elements are the most significant active elements.
Here is complete list of most common and widely used Active Electronic Components:
An energy source, whether a voltage or current source, is of 2 types – Independent and Dependent sources. Example of an Independent source is the battery which provides a constant voltage to the circuit, irrespective of the current flowing through the terminals.
Example of a dependent source is a transistor, which provides current to the circuit, depending upon the voltage applied to it. Another example is an Operational Amplifier, which provides voltage, depending upon the differential input voltage applied to its terminals.
1.2. Passive components
Passive Elements can be defined as elements which can control the flow of electrons through them. They either increase or decrease the voltage. Here are some examples of passive elements.
Some of passive elements can be listed:
II. Theory and use of all passive components
2.1. Resistor
Concept:
Resistance is a physical quantity that represents the obstruction to the flow of electric current by a conducting object. It is exactly with DC current. According to AC current it expand to impedance term. Symbol of resistor in circuit is:
The resistor unit in SI is ohm (Ω). Beside some multiples normal use are: kΩ, MΩ…
Typical technical parameters:
-Resistance value: For selection and evalution one resistor depend on resistance value
Fig.H1-Resistor band colour code
The way to read resistance value as following formula:
Resistance value=$\overline {band1\_band2\_band3} *band4 \pm band5$
-Power of resistor: Beside resistance value, power is the important parameter that designer must remind to. It represent for current capacity in circuit.
The power dissipation of resistor will caculate by formula:\[{P_d} = R{I^2} = \frac{{{U^2}}}{R}\] With each power value, resistor have different appearance and size as bellow:
-Application: Resistor have variety of applications, it use to limit current, make voltage drop, Voltage divide and make role as a load in circuit, define a timing constant.
2.2. Capacitor
Definition:
Capacitor is passive element created by two conducting plates being separated by dielectric. The process of storing energy in the capacitor is known as “charging“.To characterize the ability to discharge/charge electric, we use capacitance term. The it’s unit in SI is F (fara). Beside that also having some others unit are µF (micro Fara) ,nF (nano Fara) and pF (pico fara).
Typical technical parameters
-Capacitance Value: As discussed above, Capacitance represent for charge/discharge ability of capacitor and Its also most important when we choose a capacitor and normally display on capacitor body.
-Working Voltage: Each capacior has a maximum working voltage, if over it, capacitor’s dielectric layer will be brock down. It also important parameter need to remind when choose a capacitor, it also display on body of capacitor in normal. For almost of capacitor, this voltage refer to DC voltage, with AC voltage, this voltage mabe lower than 1,5~2 times compared DC.
– Isolation resistor: Specifications and size of dielectric layer decide to isolation resistor, with electrolytic capacitors, its performed by leakage current
Capacitor classification
-Paper Capacitor: It use the dielectric that made by thin paper. For paper capacitors with capacitance lower 0,1µF, isolation resistor minimum is 5000MΩ, with paper capacitors have biger capacitance 0,1µF, isolation resistor is lower.
Paper capacitors always use in some low frequency filter circuit.
-Ceramic capacitor: It use the dielectric that made by Ceramic. Characteristic is small size, working voltage hight. The capacitance range about 1pF to 1µF. Small ceramic capacitor using with voltage maximum is 50V
-Electrolytic Capacitor: The electrode made by puring alumium (Pure rate 99,99%). The dielectric layer is $A{L_2}{O_3}$ attached to the anode, capable of withstanding high voltage upto 800kV/mm, between the two electrodes is the dielectric. The electrolytic capacitor have big capacitance value (range 0,1µF to few thousand of µF) and bigger working voltage, so that having bigger size, trust level lower normal capacitor. Because the dielectric usually made by $A{L_2}{O_3}$. It has constant electrical conductivity, it mean that when supply DC power on, one side have big resistor, other is low resistor, so that must to polarize (+) and (-). All this electrodes will also display on capacitor body. When installing this capacitor must remind to polarity of capacitor.
Read capacitance value
– With Electrolytic Capacitor is normally included capacitance value on body like this:
-If capacitor has name with text and number will be read as rule:
Text K,Z,J correspond to pF unit, text n, H represent for nF, text M, m is uF. Position of text represent for decimal part, the number represent for capacitance value:
Ex: 2H7J= 2,7nF ±5% (Because of H is nF, J=Capacitance tolerance
-In case the code only has number without text, it will be read as rule:
+ If the numbers with a comma, its unit is uF, the comma position will show decimal number
+ If the numbers without comma, its unit is pF and the last number represent for exponentiation of 10. Special is the last number equal 0, capacitance value will be a real number.
Last text include always represent for capacitance tolerance
C: ±0,25% K: ±10%
D: ±0,5% F: ±1%
G: ±2% M: ±20%
J: ±5% S: ±50%
Some capacitors with also prefixes text represent for maximum working voltage as bellow figure:
Then, 2A corresponds to 100V, other value with working voltage as:
1H=50V, 1J=63V, 2D=200V, 2E=250V, 2G=400V, 2J=630V
And then,The above capacitor have value: $27*{10^4}pF = 270nF$ ±5% with working voltage 100V maximum.
Application
Capacitor is applied widely in electronic circuits:
– Giving AC power pass through and prevent DC power pass and there for, capacitor usually use transfer signal between amplified levels having different of DC voltage.
– Make a AC filter after rectified to flat DC. Its theory of filter power capacitor
2.3. Inductor
Definition:
Inductor is a passive element, that use in circuit having current change according to time. The inductor store energy in the form of magnetism (The energy of magnetic field created by inductor with current led on) and make the current phase delayed compared voltage a 90 degree angle.
To characterize the ability of electromagnetic induction, people introduced the concept of inductance.. The unit is H (henry). Beside that we have mH, uH…
The parameters:
– Self-inductance of coil (L): $L = {\mu _r}{\mu _0}{N^2}\frac{S}{l}$
where: S: Cross section of coil (${m^2}$)
N: Number of turn coil
l: Lengh of coil (m)
${\mu _r}$: Magnetic permeability of iron core material
${\mu _0}$ : Magnetic permeability of air
– Capacitance: The capacitance is borned between turns of coil which create a privated resonant frequency. The capacitance is borned as much as when the coil have many its turns layer.
– The limit working frequency: The inductor have a frequecy which is limited by its private capacitance (its a distributed capacitance between turns). At lower frequency, this capacitance will be ignored, because of its capacitance very much. But at higher frequency, the coil become a parallel resonant circuit.
Inductor classification:
Depend on application, the inductor have some kind of this:
– Resonant coil is the coil that always use in resonant LC circuit
– Filter coil is the coil that use DC filter
– Blocking coil is the coil that use prevent high frequency current
Depend on kind of coil core, may have some type like:
– The inductor with the air core or without core
– The inductor with ferromagnetic core
– The inductor with Ferit core
Structure:
Inductors can be formed by winding loops of electrical wire, depending on rated power and self-inductance to select cross section of coil and number turns.
Ex: The inductor have 1mH self-inductance with less than 100W rated power should be choose copper wire having dimeter 0,3mm-0,5mm and 10 turns. At higher power maybe choose greater dimeter copper wire 1,2mm and 13-15 turns.
The air or empty core coil:
The air core winding are coils wound on the ceramic core or without core. The most common are resonant coils working at high frequencies. At high frequencies, the coils are often shielded to avoid electromagnetic interference
The Ferit core coil:
The ferit core coils work at medium and high frequency, the ferit core have varies of shapes: bar, pipe, E and C shape, torus…Using a toroidal shape creates high inductance. However, it is easily saturated since it has a one-dimensional component.
The ferromagnetic core coil:
The core commonly is iron-silic or iron-niken depending on specific applications. This is all coils working at low frequency. The winding wire is an insulated enameled copper wire. The low-frequency blocking coil is used primarily to filter out voltage ripple for rectified DC supplies
How to measure inductor value:
Reading an inductor value is similar to a capacitor.
If a inductor have 102K on its body. Two first digit number is meaning number value 10 and the last number represent for exponentiation of 10. K is the error ±10% like above table. Then this inductor value is $10*{10^2}$ uH (~1mH) with 10% correction.
This post have just cocerned about 3 most popular passive element in electronics. Hope that this lession is useful for you guys and follow our website to get more next!
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