Breadboard design for simulating electronic circuits. (10+)
DIY breadboard
When developing various radio-electronic devices, I am often faced with the need to make a prototype. Of course, mathematical modeling is a great thing. But Firstly, not all schemes are amenable to mathematical modeling, but Secondly, the mathematical model is not accurate enough. In general, after checking on a computer, it is imperative to assemble it live. At first I made a test circuit board, realizing that later I would have to throw it away. But then I started using a breadboard. I don’t like breadboards based on foil PCB at all. The reason is that they do not tolerate frequent resoldering well. Due to periodic heating, the conductors begin to lag behind. So a printed prototyping board is almost as disposable as a test board designed for a specific device.
Drawing of a homemade breadboard
As a result, I made a breadboard using my own technology, which I really liked. Now I use it everywhere. The board was made from non-foil PCB. You can take a foil one and remove the foil.
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When designing and assembling new electronic circuits, their debugging is required. It is carried out on a temporary circuit board, which allows the components to be positioned quite freely in order to ensure the ability to quickly and conveniently replace them and carry out control and measurement work.
The parts in such a board can be attached by soldering, and the platform itself will be called a breadboard. To once again do not expose components to mechanical and thermal influences; installers and designers use a solderless breadboard. Radio amateurs often call this device a breadboard.
Solderless assembly prototyping board allows for installation electrical diagram and run it without using a soldering iron. In this case, you can check all the parameters and characteristics of the future device by connecting measuring and control devices to the board.
A breadboard is a plate made of a polymer material that is a dielectric. Drilled on the plate in a certain order mounting holes, into which the leads of parts - components of the future device - should be inserted.
The holes allow the connection of leads with a diameter of 0.4-0.7 mm. They are located on the board, as a rule, with a pitch of 2.54 mm.
To simulate the connections of the component leads to each other, the breadboard has special conductive plates that connect the holes in a certain order.
Typically, these connections are made in groups along the board along its long sides. There may be two or three such rows. These contact groups are used as buses for connecting power.
Between the longitudinal rows, the holes are connected by plates in groups of five. These plates are located in a direction across the board.
Near the holes in the places of future contacts, conductive plates have design features, allowing you to clamp and firmly hold the leads of the parts, while ensuring the presence electrical contact. This is the meaning of installation without soldering.
Quality prototyping boards can be assembled and disassembled while maintaining a strong and reliable connection between parts up to 50,000 times.
Breadboards produced industrially and purchased in a retail chain, as a rule, have a layout of contacts and conductive connections between the holes.
How to use it correctly
In order to successfully and efficiently use the breadboard, you must also have the following devices:
- several mounting wires with a diameter of 0.4-0.7 mm for installing various jumpers and connecting power;
- side cutters;
- pliers;
- tweezers.
Of course, a soldering iron is not needed for installation without soldering, but it may be needed to solder wires to the power supply terminals if detachable products are not available. Sometimes soldering will have to be used to implement shielding.
Knowing the location of the conductive paths on the breadboard, it is easy to install any circuit and, by connecting it to a power source, check its functionality. To assemble, you only need to insert the component leads into the connector clamps and connect them in the required sequence.
In this case, it is necessary to clearly understand the location of the conductive paths in order to prevent a short circuit. If it is necessary to make contacts between tracks on the breadboard, connectors are used.
If the diameter of the pins of the parts does not fit the mounting holes, you can solder or wind pieces of suitable wire to them. Chips and components in BAG packages are installed in the center of the board.
Preparation and shielding
In order to work with a breadboard, especially if it is intended for solderless mounting, you first need to make preparatory work. This is especially true if the board has not been used for a long time.
Preparation includes cleaning the breadboard from dust. You can use a soft brush to do this, and you can use a vacuum cleaner or a can of compressed air to clean the holes.
The next step is to test the conductive paths with a multimeter to avoid wasting time searching for a possible loss of contact when installing the circuit.
When debugging devices, they may not work correctly due to various interferences and induced currents that arise during the operation of the circuit. To eliminate this phenomenon, it is necessary to use shielding of the breadboard.
To do this, use a metal plate attached to the bottom and connected by soldering to a common bus, which will subsequently become negative.
To successfully use a breadboard for soldering and carry out quick debugging, it is advisable to purchase several breadboards different sizes.
Firstly, it will allow you to collect complex circuits separate blocks, debugging each one, and later connecting them into one device. Secondly, this way you can assemble additional devices that may be needed to control the operation of the main circuit.
It is better to purchase a development board with a set of connecting wires. They are also called “jumpers”.
But in some cases, you can save a significant amount if you buy a board for solderless mounting that is not equipped with connectors. In this case, you can make them yourself from a suitable wire.
The ideal cable is KSVV 4-0.5, used in the installation of systems fire alarm. This cable has 4 insulated cores of thin copper wire with a diameter of 0.5 mm. One meter of cable will be enough to get many connecting jumpers.
During installation, you must always reliably connect all terminals of semiconductors and microcircuits. Even if any pins are not used, they must be connected to a common bus to avoid induced currents.
Using development boards You can only use low-current parts operating from a voltage of no more than 12 V. Connect to a breadboard alternating current 220 V voltage from a household power supply is prohibited.
Proper use of a breadboard for solderless mounting will significantly simplify the assembly of the entire circuit and reduce the cost of manufacturing the device in which such a circuit will be used.
Why do they do this? This allows you to identify shortcomings, modify the circuit, and then, when the device is debugged, transfer it to a printed circuit board made of foil PCB. Because debugging and making changes to a device soldered on an etched board is always much more difficult. Of course, in this case, you can change the circuit by cutting some of the tracks, soldering the parts by surface mounting from the printing side, and so on, but this is an extreme case.
There are a lot of great collet-type breadboards on the market now, at low prices, especially if you buy them without connecting wires. An example of a device assembled on such a board can be seen below:
Let's look at how collet prototyping boards are designed. They use spring-loaded contacts, connected 5 pieces in a row by tin contacts, they are usually located vertically:
The board also has rows of holes for power supply (usually located horizontally), plus and minus, marked respectively (+) and (-) on the board. When a wire is inserted into a hole on the board, it is fixed, and if a second wire is inserted into the same group of holes connected inside the board, there will be contact between them. Breadboards are divided into collet or solderless ones, which we discussed above, and boards that need to be soldered. On factory breadboards designed for soldering, insert a wire into the hole and solder it to a contact on the board. An example of such a board is in the following photo:
All connections on such boards are made with a flexible mounting wire, soldering it to the contacts used. Such a wire can be bare, and then in order to avoid short circuits, it is soldered along the entire length to the contacts on the board, as we can see in the photo below:
Also, the wire connecting the contacts can be insulated, and then it is soldered only to those contacts that need to be connected. For example, as in the following picture:
Breadboard for soldering connection with insulated wire
This is what the device looks like from the parts side, assembled on a breadboard:
The pitch of the holes on a board designed for soldering (as well as on a collet prototyping board) is approximately 2.5 mm, and corresponds to the pitch of the legs on microcircuits made in a Dip package. Some skilled radio amateurs, apparently out of principle, make something similar to factory boards themselves, with their own hands:
When making such a board, a pattern protecting against etching is applied to the places of future contacts using a marker or, etched in the usual way, and then drilled. You can make development boards for debugging the device yourself and more in a simple way, dividing a piece of foil PCB into sections with a cutter:
In Soviet times, when there were no factory-made breadboards for sale, and even foil PCB was not available to everyone, radio amateurs also made the following breadboards:
They made such a breadboard from tin petals pressed into non-foil PCB or a piece of plywood - contacts, subsequently tinned, and radio components and connecting wires were already soldered to these petals. Material prepared by AKV.
Let's look at the design and purpose of solderless breadboards. What is their advantage over other types of assembly, and how to work with them, as well as what circuits a beginner can quickly assemble with them.
Background
The first problem that a radio amateur faces is not even a lack of theoretical knowledge, but a lack of tools and knowledge about how to install electronic devices. If you don’t know how this or that part works, this will not prevent you from connecting it according to the electrical circuit diagram, but in order to clearly and efficiently assemble the circuit, you need a printed circuit board. Most often they are made using the LUT method, but laser printer Not everyone has it. Our fathers and grandfathers painted the boards by hand with nail polish or paint, and then etched them.
Here the beginner is faced with the second problem - the lack of etching reagents. Yes, of course, ferric chloride is sold in every store of radio-electronic components, but at first there is so much to purchase and study that it is simply difficult to pay attention to the technology of etching boards made of foil PCB or getinax. And not only for beginners, but also for experienced radio amateurs, sometimes it makes no sense to etch a board and spend money on an unfinished product at the stages of its setup.
To avoid problems with finding ferric chloride, PCB, a printer and not to get punished by your wife (mother) for unauthorized use of an iron, you can practice installing electronic devices on solderless breadboards.
What is a solderless breadboard?
As the name suggests, this is a board on which you can assemble a device prototype without using a soldering iron. The layout - as it is popularly called - is available in stores in different sizes and the models differ somewhat in layout, but the principle of operation and their internal structure are the same.
The development board consists of a housing made of ABS plastic, in which there are detachable connections that resemble double metal bars between which the conductor is clamped. On the front part of the case there are holes, numbered and marked, into which you can insert wires, microcircuit legs, transistors and other radio components in cases with leads. Take a look at the picture below, where I depicted all this.
On the considered printed circuit board, the outer two columns of holes on each side are combined vertically with common buses, from which the positive bus of the power supply and the minus (common bus) are usually formed. Usually indicated by a red and blue stripe along the edge of the board, plus and minus, respectively.
The middle part of the board is divided into two parts, each part is connected in a row of five holes in a row on this particular board. The figure shows a schematic connection of the holes (black solid lines).
The internal structure of the board is shown in the figure below. Double busbars clamp the conductors, as illustrated. Bold lines indicate internal connections.
In the English-speaking environment, such boards are called Breadboard, which is the name by which you can find it on aliexpress and similar online stores.
How to work with it?
You simply insert the legs of electronic components into the holes, connecting the parts together along horizontal lines, and supply power from the outer vertical ones. If you need a jumper, they often use special ones with thin plugs at the ends; in stores they can be found under the name “dupont jumpers” or jumpers for Arduino; by the way, you can also insert it into such a breadboard and assemble your projects.
If the size of one breadboard is not enough for you, you can combine several, they are like puzzles inserted into each other, pay attention to the first picture in the article, the circuit is assembled on two connected boards. There is a spike on one of them, and a recess on the other, beveled from the outer part to the board body so that the structure does not fall apart.
Assembly simple circuits on a breadboard
It is important for a novice radio amateur to quickly assemble the circuit to make sure it works and understand how it works. Let's see what they look like different schemes on the breadboard.
The symmetrical multivibrator circuit is recommended as a first for many beginners; it allows you to learn how to connect parts in series and parallel, as well as determine the pinout of transistors. It can be assembled by surface mounting or by wiring a printed circuit board, but this requires soldering, and surface mounting, despite its simplicity, is actually very difficult for beginners and is fraught with short circuits or poor contact.
Look how simple it looks on a solderless breadboard.
By the way, please note that Dupont jumpers were not used here. In general, they cannot always be found in radio stores, and especially in stores in small towns. Instead, you can use the cores from an Internet cable (twisted pair); they are insulated, and the core is not varnished, which allows you to quickly expose the end of the cable by removing a small layer of insulation and inserting it into the connector on the board.
You can connect the parts in any way you like, as long as you provide the required circuit; here is the same diagram, but assembled slightly differently.
By the way, to describe the connections, you can use the board markings; columns are designated by letters, and rows by numbers.
For your designs, there are such power supplies, they have plugs that are mounted in a solderless board connecting to the “+” and “-” buses. It is convenient, it has a switch and a linear low-noise voltage regulator. In general, it will not be difficult for you to wire such a board yourself and assemble it.
Like this, for example, to check it. The picture shows a more “advanced” version of the printed circuit board with clamp terminals for connecting a power source. The anode of the LED is connected to the power plus (red bus) and the cathode to the horizontal bus of the work area, where it is connected to a current-limiting resistor.
Power supply on a linear stabilizer type L7805, or any other L78xx series microcircuit, where xx is the voltage you need.
Assembled tweeter circuit based on logic. Correct name such a circuit is a Pulse Generator based on logical elements of type 2i-not. First, familiarize yourself with the electrical circuit diagram.
A domestic K155LA3 or a foreign type 74HC00 is suitable as a logic chip. Elements R and C set the operating frequency. Here is its implementation on a board without soldering.
On the right, covered with white paper, is a buzzer. It can be replaced with an LED if you reduce the frequency.
The greater the resistance OR capacitance, the lower the frequency.
And this is what it looks like standard project Arduino engineer at the testing and development stage (and sometimes in the final form, depending on how lazy he is).
Actually in Lately The popularity of “bradboards” has increased significantly. They allow you to quickly assemble circuits and check their functionality, and also use them as a connector when flashing microcircuits in a DIP package, and in other packages if there is an adapter.
Limitations of solderless breadboard
Despite their simplicity and obvious advantages over soldering, solderless breadboards also have a number of disadvantages. The fact is that not all circuits work normally in such a design, let's take a closer look.
It is not recommended to assemble powerful converters, especially pulse circuits, on solderless breadboards. The former will not work normally due to the current carrying capacity of the contact tracks. You should not go beyond currents of more than 1-2 Amperes, although there are also reports on the Internet that they include 5 Amperes, draw your own conclusions and experiment.
electrical safety
Do not forget that high voltage is life-threatening. Prototyping of devices operating, for example, from 220 V is strictly PROHIBITED. Even though the conclusions are closed plastic panel, but a bunch of wires and jumpers can lead to accidental shorting or electric shock!
Conclusion
Solderless breadboard is suitable for simple circuits, analog circuits that do not have high requirements for electrical connections and accuracy, automation and digital circuits that do not work at high speeds (GigaHertz and tens of MegaHertz are too much). At the same time, high voltage and currents are dangerous and for such purposes it is better to use wall-mounted installation and printed circuit boards, while a beginner should not carry out overhead installation of such chains. The element of solderless breadboards - the simplest circuits of up to a dozen elements and amateur projects on Arduino and other microcontrollers.
