Formelly it was easier. The reduced number of components and even additional products called "hardware" were small and thus a classification was relatively simple.
We had the passive components that were those which had an electrical function but did not amplify or generate signals. In this group were included resistors, capacitors, inductors, etc.
And, on the other hand, we had the active components that could be semiconductors, in which case included diodes, transistors, semiconductor and optoelectronic sensors, and integrated circuits in a separate group.
Even integrated circuits were further classified into groups, separating the logical families of microcontrollers, ASICs, etc.
And apart from all of this we had the hardware which was the elements that did not have a properly electrical function modifying signals. In this group were included the sockets of the components, connectors, wires, keys, etc.
With the advancement of electronic technology, a multitude of new electronic products became available and with that, the classification also changed with the creation of new groups and subgroups which are now adopted by most companies in their catalogs and pages on the Internet.
Let's look at this classification in general, although it may have variations, because it is very subjective. Thus, a component that which can indicate as belonging to one group in a specific company, for another company it can be in another group.
The Common Classification:
In order for the reader to have an idea of how a classification of electronic and similar products can be made, let's take as an example the one adopted by Mouser Electronics on its home page: www.mouser.com
As we can see, component categories are diverse, including passive components, test instruments, tools, hardware, semiconductors, and electromechanical devices. We will detail these categories for a better understanding of our readers.
Circuit Protection
In current devices, with integrated circuits and other delicate semiconductor components, a circuit protection is critical. Thus, in addition to the old fuses that were the traditional elements for this type of application, nowadays we have a multitude of additional devices. For the reader to have an idea, by the time we wrote this article, Mouser Electronics had in its inventory more than 126,000 different types of components in this category.
So, in addition to circuit breakers and accessories, we highlight circuit protection kits, ESD suppressors, TV diodes, gas discharge tubes, devices to protect LED circuits, resettable fuses, transient suppressors, thyristors and varistors.
It is interesting to note that components, which fall into other categories, are also placed in this one, like thyristors and fuse holders.
Connectors
When we talk about connectors we should not only think of a few types such as plugs, jacks and others of common use. The world of connectors is huge, considering the types of signals, possible shields to work in hostile environments and hundreds of patterns, which depend on specific applications.
In this category, for example, when we wrote this article, Mouser Electronics had over 1,200,000 different types of connectors.
Usually connectors are classified by categories, which take into account applications such as audio / video, automotive, back connectors and panels, connectors for printed circuit boards, I/O connectors, junction systems, lighting, sockets, RF connectors and a lot more.
Electromechanical (Electromechanical)
In the past, this category had only the relays, solenoids and motors. However, if we analyse the new components and some special applications, mainly for use in automation, we find much more. At Mouser Electronics, for example, we found over 275,000 components in this category.
In addition to electromechanical audio devices, for example, speakers and microphones (remember that they have moving parts, so they are in this category), we have breakers, encoders, industrial automation devices like relays, solenoids, timers, and much more.
Embedded Solutions
This category of products is relatively new. With the increase of amount of non-electronic devices, but with electronic parts as integral, the embedded electronics came to occupy a very important space in the world of products and components.
Thus, many companies, such as Mouser Electronics, include products, which fall into this category into a special group that can be accessed separately.
In it we find everything that can be embedded in a device or even used in a vehicle. This makes products and components that are also found in other categories to be found here, such as audio modules, memory cards, displays, development tools, sensors, etc.
Anyway, when we think of stuffing something into an equipment, be it an appliance, an IoT application, a vehicle or a wearable, the section that must be visited to look for components is this.
Enclosures
Of course, enclosures, cabinets, racks, and boxes are hardware categories in most classifications, but many vendors prefer to classify them into a separate group such as Mouser Electronics that has more than 10,000 different types of them.
Engineering Tools
With the popularization of microcontrollers in a multitude of new applications such as IoT, wearable, embedded, many manufacturers offer tools and other features like software, which facilitate the development of new products.
It is therefore a new category, which includes development boards, rating boards and development softwares. In the case of Mouser, the several tools and resources are divided into subcategories with over 28,000 products available.
We then have the tools to develop analog and digital circuits, communication, embedded, fiber optics, LEDs, RF and wireless, sensors and more.
We observed that some of these categories may also have their components included in others, such as LEDs and embedded LEDs, as well as sensors.
Industrial Automation (Industrial Automation)
Industrial applications must meet differentiated specifications that take into account the rough environment of a factory besides other ones. Thus, many components which meet these conditions and that can be found in other categories are also present in this group, as in the case of Mouser Electronics.
In the case of Mouser there are more than 38,000 products including controllers, meters, tachometers, power devices, relays and solenoids, sensors, switches, timers and more.
LED Lighting
LEDs are definitely replacing all types of light bulbs. However, when we think of LED lighting it is not just these components that should be considered. In addition to a multitude of types that differ in size, shape, power and type of emission (spectrum) we have to consider all the circuits of support and also the mechanical resources.
Thus, Mouser Electronics in its list of more than 68 000 related products includes not only LEDs, modules, electronic drivers (fuses), the mechanical resources and optical resources, as well as special connectors which are required in its application.
Modules in particular are important because, unlike ordinary light bulbs that operate directly at high voltages; LEDs require constant current sources which, in many cases, must also include protection features.
Optoelectronics
Although the previous item dealing with LEDs is actually a branch of optoelectronics, in many cases it is separated as we have seen here. So many products, which are also in the previous item, will be found in this and obviously many others.
Mouser Electronics includes more than 122,000 products in this category, by the time we wrote this article, which besides the LEDs in general are not only for lightning as the previous item, it has many displays, optical fiber components, infrared, lasers, bulbs (they are still used in many applications), optical detectors, optical switches, optical couplers, and more.
Passive Components
Going back to the past, we found many of the components that we mentioned at the beginning of this article and that did not changed purpose, although they increased in quantity of types. We have resistors, capacitors, potentiometers, trimmers, but besides them some others can also be found in other groups and we can even say that they could really only be in other groups.
This is the case of encoders, EMI filters, ferrites, thermistors and varistors.
In this giant group of components, Mouser Electronics offers more than 1,000,000 different types.
Power
In fact, the components of this group may fall into several other categories. The separation is done by many suppliers, such as Mouser Electronics, because they work with intense currents, are connected directly to the power grid, or even supply high amounts of power to power a circuit.
We then have power cables, plugs, battery holders, and batteries, connectors, and so on, in this group of what they might call power hardware. And, in the case of components themselves, we have batteries, DC/DC converters, AC/DC, inverters, consumer controllers, supercapacitors, transformers and others.
Semiconductors
This category was one of the few that has not changed since the times when the types of components were separated. In it we basically include components made from semiconductor materials such as diodes, transistors, thyristors, etc.
Of course, diodes have several categories like zeners, tunnel, as well as transistors, which can be bipolar, FETs, MOSFETs, etc.
Although it sounds like little, Mouser Electronics has in stock more than 500,000 component types in this group.
Sensors
Although a good part of the sensors can be classified in the group of the passive components and many of them are semiconductor devices, also found in that group, by its quantity and specific range of applications, it is preferred to group these components into a single category, as is the case of Mouser Electronics. This certainly facilitates access to a type required for a specific application.
In this group, we have sensors for all types of applications and with the most diverse characteristics like audio sensors, sensors for biomedical use, touch sensors, encoders, sensors of fluid, power, load, level, movement and position. We also have displacement, proximity, pressure sensors and completing the necessary hardware and accessories to use. More than 17,000 types are available at Mouser.
Test and Measurement
In this group, we do not have components as such but devices. They are test and measurement devices of the most diverse types for the most diverse purposes made available for the purpose of equipping the laboratory of companies, makers and schools.
In this category of products, Mouser Electronics, for example, includes analyzers, audio test equipment, batteries, power supplies, component testing, oscilloscopes, frequency meters, multimeters, function generators, and more.
Thermal Management
In the normal classification, the components of this category could be included in hardware, however, with the evolution of temperature control technology of electronic circuits, also came into action features, which involve circuits, special components like sensors and more.
So in this specific group with more than 31,000 products in the case of Mouser Electronics, we find heat sinks as passive but much more like fans, temperature sensors, thermal breakers, interfacing products, thermistors and thermoelectric pairs.
An important case to be analyzed is the specific heat sinks for high power LEDs used in lighting, which occupy a special category within this group.
Tools
In “ancient times”, it was said that a screwdriver was enough for a good technician to perform any kind of repair on electronic equipment. Of course, nowadays it is not so.
In addition to a huge variety of common tools and resources, we have many, which are used under special conditions.
Thus, an important category of all technology-related product suppliers, such as Mouser Electronics, is that of tools which evidently includes pliers, well known screwdrivers, but some modern products of specific use like adhesive tapes, antistatic control products , chemicals, labeling and signaling, special prototyping products, boxes for component storage, etc.
Wires and Cables
This is an interesting category, which could also be included in the group of hardware or power, which actually occurs, but presents a specific product line. In the case of Mouser Electronics there are more than 140,000 different products.
We then have cable sets, coaxial cables, FFC/FPC jumper cables, fiber optic cables, flat cables, conductive cables and many more.
Conclusion:
Nowadays it is very difficult to include certain products used in electronics in a single application category. This is due to the increasing convergence that entwines the products in such a way that in each application we have elements of different natures.
An embedded product requires discrete components, semiconductors, hardware, cables, and sensors.
Likewise, an IoT application has its specific boards with microcontrollers, semiconductors, discretes and hardware, as well as cables and power managers.
How to classify all this is a problem that requires a very great sensitivity because it is difficult to say that a component fits into a single group.
In this article we have given an idea of ??how many suppliers, such as Mouser Electronics, classify their products in order to make their customers' access as easy as possible, always remembering that in the specification page of each one we have the suggestion of equivalents and also access to datasheets.
