Electronics are a fundamental part of most operations in the present-day world. It transcends every sector from industry, education, transport, etc., to our own homes. While important to every industry on the planet, electronics also rely on crucial components to function. No wonder you will always live to witness the eternal discussion about the active components vs. passive components question. But what exactly does it mean? This article will dissect this question and take you through it to better understand electronic components.
Dissecting the Question: Active Components VS Passive Components
A critical differentiating factor between electronic components is whether they are active or passive. However, it is not a straightforward aspect for people to understand. Many people still cannot understand the difference between active components and passive components. So what does it entail?
Active components encompass circuit parts that depend on external sources of power to modify or control electrical signals. It includes components like silicon-controlled rectifiers, transistors, integrated chips, display devices, diodes, etc. All of the components detailed need electricity to function (modify the electric flow)
Passive components, on the other hand, do not require an external source of power to operate. It depends on other properties in controlling electrical signals. Consequently, passive components solely need the current present or traveling through the circuit to function. Some of the passive components comprise transformers, resistors, transducers, inductors, etc.
While the active components vs. passive components discussion is important for electronic hobbyists, engineers, and students, it is instrumental in understanding that an electronic device cannot function without either. But before getting into the nuances of each type of component, it helps to understand the context upon which they apply.
Electronic Circuits and Components
Both active and passive components operate within an electronic circuit. It thus ensures that an electronic device or equipment functions as anticipated in its intended application. As a result, it becomes crucial to comprehend what a circuit implies and how the different types of electronic components function within this context.
Firstly, electronic circuits refer to a structure instrumental in controlling and directing electric current for various functions. It includes functions such as computation, signal amplification, data transfer, etc. The circuit structure consists of inductors, transistors, and all other components already enumerated under the two classifications of active and passive components.
The number of electronic components besides the complexity of the circuit can change based on the application of the circuit. For simple applications, a modest circuit will consist of a conducting path, a load, and a voltage source.
- Conductive path. It allows the flow of current and primarily consists of conductive copper traces. Such traces are copper sheets that get laminated to non-conductive substrates such as a glass-epoxy resin (FR4).
- Voltage source. It often comes as a two-terminal device that provides a voltage between two circuit points to allow current flow. Such sources include generators, power systems, or batteries.
- Load. It represents a circuit element that has to consume power to operate or execute a specific function. Loads in a circuit can be diverse based on the complexity. It can include capacitors, transistors, resistors, etc., for complex loads to a simple light bulb for the simplest loads.
Types of Electronic Circuits
Circuits are essential in the operation of any electronic equipment or device. But for a circuit to work, it needs the flow of current, which is possible through the formation of a loop. Diverse electronic circuits exist and include open circuits, closed circuits, short circuits, printed circuit boards, and integrated circuits.
Open circuit. It is a circuit that does not operate in a loop system like other circuits. There is impediment of the current flow as component (s) either accidentally or by design they become disconnected or broken.
Closed-circuit. The circuit, unlike the open circuit, forms a loop with current flowing without interruptions. It can comprise complete circuits without any particular function—for instance, a complete circuit connected to dead batteries.
Short circuit. It is where the electrical circuit forms a low-resistance connection. The points at which such a connection occurs allow the flow of current instead of the designed path. Such circuits occur unintendedly and often lead to severe accidents.
PCBs. It is a complex form of electronic circuit necessary for complex applications synonymous with most electronic devices or appliances. It possesses tiny electronic components arranged in a specific way. You can connect such components with conductive layers on top of a non-conductive substrate.
Integrated circuits. It is an advanced form of electronic circuit that allows for millions of electronic components. Modern appliances or devices such as mobile phones or computers use these ICs. Integrated circuits come complex and tiny as they can fit into small silicon chips.
Electronic Components
Advances in technology have enhanced electronic circuits such as PCBs and integrated circuits, but the technology used in building them. For instance, currently, most of the circuit building processes are fully automated. The active components vs. passive components arrangement follow a set design prescribed during the design phase. Additionally, the number of such components depends on the complexity of the designed circuit.
The manufacturing and assembly process of intricate electronic circuits such as integrated circuits and printed circuit boards can get complicated. It stems from the sheer number of components, the limited space upon which they need to get assembled, advanced functionality, and the required level of quality assurance, as a result. ICs and PCBs require specialized and modern equipment, the latest technologies, and highly skilled craftsmanship.
It becomes necessary to rely on RayMing PCB and Assembly for expert and certified electronic production services. Such services include electronic component sourcing (both active components and passive components), fabrication and assembly of ICs and PCBs, besides other services such as delivery and customer care.
Since fabrication and assembly of ICs and PCB predominantly require active and passive components as part of the circuit. It is crucial to consider the following components, their composition, functionality, and importance to your electronic circuit during the design phase.
Passive Components
Capacitors
It primarily gets utilized in building diverse electronic circuit types—the passive two-terminal part or component stores energy in an electrostatic form within the electric field. In short, it functions as a tiny rechargeable battery. However, the main difference between a capacitor and a battery is that it can discharge and charge in a second (the converse is also true).
It’s Composition
A capacitor can come in various sizes and shapes, though the primary parts are the same. It has two electrical plates or conductors separated by an insulator or dielectric stacked in between. Conductive materials like thin aluminum or metal films make up the plate. In contrast, the dielectric primarily consists of non-conductive materials like ceramic, glass, paper, air, mica, or plastic film. It is possible to insert the two protruding ends of the plate when fixing the capacitor.
It’s Functionality
A voltage gets applied over two plates by connecting them to a source to generate an electrical field. As a result, one plate will accumulate the positive charge as the other collects the negative charge on the opposite side. It continues functioning post disconnection to the power source. Therefore, it will transmit the stored energy to a load immediately after connecting it to a load.
Significance
Besides resembling batteries, capacitors can function differentially. It can block direct current as it allows for the flow of alternate current. Alternatively, it can smoothen the output emanating from the power source. It is also instrumental in power flow and voltage stabilization. Additionally, it can correct the power factor, instrumental in giving enough starting torque to motors (single-phase). Remember, filter, hold-up, and timer capacitors have different applications.
Resistors
It is also a two-terminal electrical component that primarily resists the current flow. Resistors are potentially the simplest electronic circuit elements. Additionally, it is typical of every electronic circuit as it is inherent. In most cases, resistors will come with color codes.
Its composition
A resistor is not fancy, as resistance is an inherent property of almost every conductor. It comprises a wrapped copper wire around a non-conductive material like ceramic. The copper thinness and the amount of turns are proportional to the amount of resistance. The copper wire needs to become thinner for higher resistance, with the number of turns also increasing.
Resistors can also come in a carbon film’s spiral pattern. However, the ideal circuit for carbon film resistors is the low power circuit. It arises because the carbon film, unlike its wired counterparts, is unprecise. The wire terminal scan gets attached on both ends because resistors do not adhere to polarity within a circuit.
It’s Functionality
Resistors perform an instrumental role in controlling the current and voltage in electronic circuits. The thinness and thickness of the resistor wire play a fundamental role in allowing the amount of current to flow through, similar to water and pipes.
Significance
Resistors are instrumental in limiting the current flow in a circuit. As a result, it protects other components from potential damage. It is also valuable for dividing voltage by reducing it to the level desired in a circuit. For instance, circuit parts like the microcontroller may need a lower voltage than the rest of the circuit. Further, resistors can get utilized together with capacitors in building integrated circuits possessing resistor-capacitor arrays (RC networks or filters). RC networks are pivotal in suppressing EMI (electromagnetic interference) or RFI in laptop or computer I/O ports, WANs, LANs, etc.
Inductors
Also called reactors, inductors are passive two-terminal components. It stores energy (within the magnetic field) and returns it to the electronic circuit when required. Two inductors, when placed alongside each other (without any touching), affect each other. The magnetic field created by the first inductor influences the second, a breakthrough finding that led to the discovery or invention of transformers.
Composition
As a component, it is one of the simplest as it is solely copper (wire coil). The number of coil turns is proportional to the inductance. However, coiling the copper wire around ferromagnetic materials like iron enhances the inductance. Additionally, the core shape can also enhance the inductance. However, joining inductors within an IC is complex, and thus, it gets replaced with resistors.
Functionality
Current, when passed through any conductive wire, it forms a magnetic field. It is the same principle that an inductor uses. The magnetic field generated resists the alternating current while allowing direct current through. What’s more? The magnetic field stores energy.
Significance
It is an instrumental component, though tough incorporating it into a circuit owing to its size. In integrated circuits, for instance, inductors get replaced by resistors because of their bulky nature. However, it finds application in selecting specific frequencies desired in tuned electronic circuits. It can also function as an inductor choke by converting alternate current supply into direct current.
Quartz Crystal
It is a passive electronic component primarily used in the form of resonators in circuits. Quartz naturally occurs as a silicon form though capable of getting produced synthetically. It possesses a piezoelectric effect that allows for AC voltage generation, primarily when physical pressure gets instigated. It comes in numerous sizes based on the intended application.
Composition
The quartz crystal is instrumental in creating crystal oscillators and can come either in rectangular slabs or hexagonal, with the ends forming pyramids. The quartz crystal has two cutting techniques, the Y and the X cuts. It usually gets sandwiched by holding plates with the outer shape proving rectangular, square, or cylindrical.
Functionality
The application of an alternating voltage on the crystal leads to mechanical vibrations. The size and cut of the crystal determine the oscillations or vibration’s resonant frequency, which generates a continuous signal.
Significance
The remarkably high Q-factor in a quartz crystal makes it a perfect filter in circuits. Therefore, you can find digital watches as the timing element and microprocessor boards as the oscillator clock.
Active Components
Diode
It comes as a two-terminal component that permits the unidirectional flow of current. It can therefore get considered as an equivalent of an electronic check valve. In most instances, the diode converts AC (alternating current) to DC (direct current). You will find a semiconductor substance or material present in a diode. Alternatively, it can come as a vacuum tube. But in today’s world, a lot of diodes comprise a silicon semiconductor material.
Composition
Diodes primarily comprise vacuum or semiconductor materials. A semiconductor diode comes as either n-type or p-type semiconductors. It contains silicon, selenium, or germanium and gets referred to as p-n junction diodes. On the other hand, the vacuum diode operates on a vacuum principle where the anode and cathode are inside a glass tube vacuum.
Functionality
A vacuum diode operates on the principle of electron cloud action. For instance, when a cathode gets heated, the invisible electron cloud forms within the glass vacuum, alternatively inferred as a space charge. As much as the cathode emits electrodes, the negative vacuum or space repels the electrodes. As a result, no electrons get to the anode, and the current fails to flow through the electronic circuit.
The p-n junction diode, on the other hand, works differently. For instance, the p-type gets tampered with with boron to leave it with positively charged holes. The n-type gets tempered with antimony, which incorporates more electrons making it negatively charged—connecting the n- and p-types to the positive and negative terminals, respectively. Such a connection allows for the flow of current. However, when the terminals get reversed, the flow of current stops. It arises because the holes and the electrons get pushed from each other.
Significance
It applies in converting AC to DC, shielding solar panels, signal demodulation, and protecting the load from voltage spikes.
Transistors
It comprises one of the most vital components in an electronic circuit. A transistor is a small semiconductor device having three terminals. It primarily gets utilized as switching devices or amplifiers. Transistors can switch something off or on, devoid of any movement.
Composition
It is mostly created using silicon though previous models had germanium. Silicon transistors have a better temperature tolerance besides cheaper manufacturing costs. While BJT or Bipolar Junction Transistors comprised of PNP and NPN exist, all have three pins in “collector,” “base,” and “emitter.”
Functionality
NPN and PNP refer to the layer sequence of the semiconductor material of the transistor. An NPN implies the p-type silicon slab getting sandwiched between two n-type layers. The emitter gets attached to one of the n-types as the collector gets attached to the second n-type. Its base gets connected or attached to the p-type. The p-type silicon’s extra holes work as barriers to the current flow. A positive voltage gets applied to the collector and base besides charging the emitter negatively. The electron flow begins from the emitter towards the collector. The PNP functions differently because of a different voltage allocation.
Significance
Transistors work as both amplifiers and switches in a lot of electronic circuits. Therefore, it finds application in hearing aids, calculators and computers, display drivers, power regulators, touch and light sensors. Additionally, it finds application in audio amplifiers and alarm systems.
Active Components Vs. Passive Components: Differences
Plenty of differences exist between passive and active components. As a designer, understanding each classification, the components, and their differences becomes key in designing electronic circuits. The difference between the two often becomes apparent from their respective definitions, though this trickles down to the minute details. All the existing differences come along in functionality, type of source, current flow regulation, and power gain. So what are the differences?
Nature of the Source
All active components provide power to electronic circuits, while passive components use energy from electronic circuits. Excellent examples include transistors, ICs, diodes, SCR, etc., for active components and capacitors, resistors, inductors, etc., for passive components.
Component Functionality
Active components produce energy either in current or voltage, while passive components store energy in the same forms (current or voltage).
Power Gain
Active components can offer power gain. On the other hand, passive components cannot give you any.
The flow of the Current
While active components can control the flow of current in circuits, passive components lack this ability.
External source requirement
Active components need to have external sources to operate. However, the opposite holds for passive components.
Type of Energy
All active components prove energy donors, while passive components are the opposite. Passive components always accept energy.
The subtle differences between active and passive electronic components are often simple to articulate. However, the differences in electronic components always tap into the fundamental basis of the design, which is energy conservation. Energy cannot get destroyed, neither can you form it. What’s more? Machines cannot function with 100% efficiency. Therefore, passive circuits will always tend to lose some power under deployment or utilization.
Applications of Active Components
Electronic parts are vital and often hidden in most electronic and electrical systems and devices around us. Active components, part of the electronic components, find applications in diverse areas. It includes sound systems, lighting bulbs, and phones. It also applies to computers, cars, etc. The definition “active” implies that you will most likely find these components in all electronic devices. Typical examples apart from the detailed ones range from devices with integrated circuits (those that possess some computing power), devices having built-in displays or batteries to light-emitting diodes (LED lights).
Applications of Passive Components
Passive components are similarly important in electronic circuits and, by extension, electronic devices. For instance, an incandescent bulb (light) comes as an incredible illustration of a transducer. It converts electrical power or energy to heat and light energy. Loudspeakers also utilize transducers in converting electrical input to mechanical output. As a result, the speaker cones vibrate to generate sound waves that we can decipher.
Sensors are also another form of transducers with long-term use in scientific studies or research. It has increasingly gained universal acceptance and popularity through the drive of making machines and appliances “smart.”
Other important application areas for passive components entail radio frequency and microwave applications. Radiofrequency applications include areas such as keyless and remote entry systems that depend on inductors. It is also vital to mention antennas primarily found in GPS devices, radios, wireless routers, and modems. You can also find the passive component (antenna) in public transport.
Final Thoughts
Every electronic design enthusiast needs to understand the intricacies of the active components vs. passive components subject. It improves your understanding of the individual components and how to arrange them within an IC or PCB.
