Schemes of homemade measuring instruments
A device circuit developed on the basis of a classic multivibrator, but instead of load resistors, transistors with opposite main conductivity are included in the collector circuits of the multivibrator.
It's good if you have an oscilloscope in your laboratory. Well, if it is not there and it is not possible to buy it for one reason or another, do not be upset. In most cases, it can be successfully replaced by a logic probe, which allows you to monitor the logical levels of signals at the inputs and outputs of digital integrated circuits, determine the presence of pulses in the controlled circuit and reflect the received information visually (light-color or digital) or audio (tone signals of various frequencies ) forms. When setting up and repairing structures based on digital integrated circuits, it is not always so necessary to know the characteristics of pulses or the exact values of voltage levels. Therefore, logic probes make the setup process easier, even if you have an oscilloscope.
A huge selection of different pulse generator circuits is presented. Some of them generate a single pulse at the output, the duration of which does not depend on the duration of the triggering (input) pulse. Such generators are used for a wide variety of purposes: simulating input signals of digital devices, when testing the performance of digital integrated circuits, the need to supply a certain number of pulses to a device with visual control of processes, etc. Others generate sawtooth and rectangular pulses of various frequencies and duty cycles and amplitudes
Repair of various components and devices of low-frequency electronic equipment and technology can be significantly simplified if you use a function generator as an assistant, which makes it possible to study the amplitude-frequency characteristics of any low-frequency device, transient processes and nonlinear characteristics of any analog devices, and also has the ability to generate rectangular pulses forms and simplification of the process of setting up digital circuits.
When setting up digital devices, you definitely need one more device - a pulse generator. An industrial generator is a rather expensive device and is rarely on sale, but its analogue, although not as accurate and stable, can be assembled from available radio elements at home
However, creating a sound generator that produces a sinusoidal signal is not easy and quite painstaking, especially in terms of setup. The fact is that any generator contains at least two elements: an amplifier and a frequency-dependent circuit that determines the oscillation frequency. It is usually connected between the output and input of the amplifier, creating positive feedback (POF). In the case of an RF generator, everything is simple - just an amplifier with one transistor and an oscillating circuit that determines the frequency. For the audio frequency range, winding a coil is difficult, and its quality factor is low. Therefore, in the audio frequency range, RC elements are used - resistors and capacitors. They filter the fundamental harmonics quite poorly, and therefore the sine wave signal turns out to be distorted, for example, limited by peaks. To eliminate distortion, amplitude stabilization circuits are used to maintain a low level of the generated signal when the distortion is not yet noticeable. It is the creation of a good stabilizing circuit that does not distort the sinusoidal signal that causes the main difficulties.
Often, after assembling the structure, the radio amateur sees that the device does not work. A person does not have sense organs that allow him to see electric current, electromagnetic field or processes occurring in electronic circuits. Radio measuring instruments - the eyes and ears of a radio amateur - help to do this.
Therefore, we need some means of testing and checking telephones and loudspeakers, audio amplifiers, and various sound recording and sound reproducing devices. Such a tool is amateur radio circuits of audio frequency signal generators, or, more simply, a sound generator. Traditionally, it produces a continuous sine wave whose frequency and amplitude can be varied. This allows you to check all ULF stages, find faults, determine the gain, take amplitude-frequency characteristics (AFC) and much more.
We consider a simple homemade amateur radio attachment that turns your multimeter into a universal device for testing zener diodes and dinistors. PCB drawings available
Our website contains materials that you will find not only interesting, but also very useful. This section is dedicated to “Practical diagrams of various devices”, it contains a lot of reference materials, information for beginner radio amateurs and not only, professionals will also find something useful for themselves. After all, people who want to develop learn throughout their lives. They say that it is impossible to know everything, we confirm this hypothesis by posting more and more new materials that cover science, electronics and constantly provide new knowledge.
We offer cooperation to experienced radio amateurs; they can share their experience on the pages of our website with beginners, that is, still completely amateurs. Our site will be useful in that participants can write comments on articles, discuss their problems on the forum, thereby sharing their experiences with each other.
If you want to develop, but you simply have little experience, our site will give you great benefit, the presentation of information is not at the most complex level, but in order to understand the electrical circuits of different devices, get acquainted with the description of the principles of their operation, you need to work a little. Therefore, if you are lazy and restless, and do not want to work to achieve something, then pass by, our site is not for you. There is no “I want to know everything” button on our website.
Our initial and primary goal is to meet the expectations of our users. We want you to expand your technical knowledge or strengthen your existing ones. You will definitely need them, since for many, the hobby of amateur radio often develops into a form of active income.
Article updated: March 25, 2019In this article we will look at a differential pressure gauge, what it is, what its function is, and what it is used for. A differential pressure gauge is a device that measures the difference in pressure between two places. Differential pressure gauges can range from devices simple enough to build at home to complex digital equipment. Function Standard pressure gauges are used to measure the pressure in a container by comparing it...
Article updated: 02/18/2019 Article updated: 02/17/2019 Article updated: 02/14/2019 Article updated: 02/10/2019 Article updated: 01/31/2019 Article updated: 01/30/2019 Article updated:11/13/2018Post navigation
- Practical diagrams of different devices
Recently, having learned that I am a radio amateur, on the forum of our city, in the Radio thread, two people turned to me for help. Both for different reasons, and both of different ages, already adults, as it turned out when they met, one was 45 years old, the other 27. Which proves that you can start studying electronics at any age. They had one thing in common: both were somehow familiar with technology, and would like to independently master the radio business, but did not know where to start. We continued our conversation in In contact with, to my answer that there is a sea of information on this topic on the Internet, study it - I don’t want to, I heard about the same thing from both - that both do not know where to start. One of the first questions was: what is included in the required minimum knowledge of a radio amateur. Listing the necessary skills for them took quite a lot of time, and I decided to write a review on this topic. I think it will be useful to beginners like my friends, to everyone who cannot decide where to start their training.
I’ll say right away that when learning, you need to evenly combine theory with practice. No matter how much you would like to quickly start soldering and assembling specific devices, you need to remember that without the necessary theoretical basis in your head, at best, you will be able to accurately copy other people’s devices. Whereas if you know the theory, at least to a minimum extent, you will be able to change the scheme and adapt it to your needs. There is a phrase that I think is known to every radio amateur: “There is nothing more practical than a good theory.”
First of all, you need to learn how to read circuit diagrams. Without the ability to read schematics, it is impossible to assemble even the simplest electronic device. Also, subsequently, it will not be superfluous to master the independent drawing up of circuit diagrams in a special one.
Soldering parts
You must be able to identify any radio component by appearance, and know how it is indicated on the diagram. Of course, in order to assemble and solder any circuit, you need to have a soldering iron, preferably with a power no higher than 25 watts, and be able to use it well. All semiconductor parts do not like overheating, if you are soldering, for example, a transistor onto a board, and you were unable to solder the output in 5 - 7 seconds, pause for 10 seconds, or solder another part at this time, otherwise there is a high probability of burning the radio component from overheating.
It is also important to solder carefully, especially the terminals of radio components located closely, and not create “snot” or accidental short circuits. Always, if in doubt, ring the suspicious location with a multimeter in sound testing mode.
It is equally important to remove flux residues from the board, especially if you are soldering a digital circuit, or with flux containing active additives. You need to wash it off with a special liquid or 97% ethyl alcohol.
Beginners often assemble circuits by surface mounting, directly on the terminals of the parts. I agree, if the leads are securely twisted together and then soldered, such a device will last a long time. But in this way it is no longer worth assembling devices containing more than 5 - 8 parts. In this case, you need to assemble the device on a printed circuit board. The device assembled on the board is characterized by increased reliability; the connection diagram can be easily traced along the tracks, and, if necessary, all connections can be checked with a multimeter.
The disadvantage of printed wiring is the difficulty of changing the circuit of the finished device. Therefore, before laying out and etching a printed circuit board, you always first need to assemble the device on a breadboard. You can make devices on printed circuit boards in different ways, the main thing here is to follow one important rule: the copper foil tracks on the PCB should not have contact with other tracks, where this is not provided for in the diagram.
In general, there are different ways to make a printed circuit board, for example, by separating sections of foil - tracks, with a groove cut through a cutter in the foil made from a hacksaw blade. Or by applying a protective pattern to protect the foil underneath (future tracks) from etching using a permanent marker.
Or using LUT technology (laser ironing technology), where the tracks are protected from bleeding by baked-on toner. In any case, no matter how we make a printed circuit board, we first need to lay it out in the tracer program. I recommend it for beginners; it is a manual tracer with great capabilities.
Also, when laying out printed circuit boards yourself, or if you have printed a finished board, you need the ability to work with the documentation for the radio component, with the so-called Datasheets ( Datasheet), pages in PDF format. There are datasheets on the Internet for almost all imported radio components, with the exception of some Chinese ones.
On domestic radio components, you can find information in scanned reference books, specialized sites that post pages with the characteristics of radio components, and information pages of various online stores such as Chip & Dip. The ability to determine the pinout of a radio component is required; the name pinout is also used, because many, even two-terminal parts, have polarity. Practical skills in using a multimeter are also required.
A multimeter is a universal device, with the help of just one, you can carry out diagnostics, determine the pins of a part, their performance, the presence or absence of a short circuit on the board. I think it would not be amiss to remind, especially young beginner radio amateurs, about observing electrical safety measures when debugging the operation of the device.
After assembling the device, you need to arrange it in a beautiful case so that you won’t be ashamed to show it to your friends, which means you need metalworking skills if the case is made of metal or plastic, or carpentry skills if the case is made of wood. Sooner or later, any radio amateur comes to the point that he has to do minor repairs to equipment, first his own, and then, as he gains experience, from friends. This means that it is necessary to be able to diagnose a malfunction, determine the cause of the breakdown, and its subsequent elimination.
Often, even experienced radio amateurs, without tools, find it difficult to unsolder multi-pin parts from the board. It’s good if the parts need to be replaced, then we bite off the leads from the body itself and solder the legs one at a time. It is worse and more difficult when this part is needed to assemble some other device, or repairs are being made, and the part may need to be soldered back later, for example, when searching for a short circuit on the board. In this case, you need tools for dismantling, and the ability to use them is a braid and a desoldering pump.
I do not mention the use of a soldering gun, due to the frequent lack of access to it for beginners.
Conclusion
All of the above is only part of the required minimum that a novice radio amateur should know when designing devices, but having these skills, you can already assemble, with a little experience, almost any device. Especially for the site - AKV.
Discuss the article WHERE TO START FOR A RADIO AMATEUR
When studying electronics, the question arises of how to read electrical diagrams. The natural desire of a novice electronics engineer or radio amateur is to solder some interesting electronic device. However, at the initial stage, sufficient theoretical knowledge and practical skills are, as always, not enough. Therefore, the device is assembled blindly. And it often happens that a soldered device, on which a lot of time, effort and patience was spent, does not work, which only causes disappointment and discourages a novice radio amateur from getting involved in electronics, having never experienced all the delights of this science. Although, as it turns out, the scheme did not work due to a mere trivial mistake. It would take a more experienced radio amateur less than a minute to correct such an error.
This article provides useful recommendations that will help minimize the number of errors. They will help a novice radio amateur assemble various electronic devices that will work the first time.
Any radio-electronic equipment consists of individual radio components, soldered (connected) to each other in a certain way. All radio components, their connections and additional symbols are displayed on a special drawing. Such a drawing is called an electrical diagram. Each radio component has its own designation, which is correctly called conventional graphic designation, abbreviated as UGO. We will return to UGO later in this article.
In principle, two stages can be distinguished in improving the reading of electrical circuits. The first stage is typical for installers of radio-electronic equipment. They simply assemble (solder) devices without delving into the purpose and operating principle of its main components. In fact, this is boring work, although soldering is good, you still need to learn. Personally, I find it much more interesting to solder something that I fully understand how it works. There are many options for maneuvers. You understand which denomination, for example, is critical in this case, and which one can be neglected and replaced with another. Which transistor can be replaced with an analogue, and where should only a transistor of the specified series be used. Therefore, I personally prefer the second stage.
The second stage is inherent to developers of electronic equipment. This stage is the most interesting and creative, since one can improve endlessly in the development of electronic circuits.
Entire volumes of books have been written in this area, the most famous of which is “The Art of Circuit Design.” It is to this stage that we will strive to approach. However, this will require deep theoretical knowledge, but it’s all worth it.
Power supply designation
Any radio-electronic device is capable of performing its functions only in the presence of electricity. There are fundamentally two types of electricity sources: direct and alternating current. This article discusses sources exclusively. These include batteries or galvanic cells, rechargeable batteries, various types of power supplies, etc.
There are thousands of thousands of different batteries, galvanic cells, etc. in the world, which differ in both appearance and design. However, they are all united by a common functional purpose - to supply electronic equipment with direct current. Therefore, in the drawings of electrical circuits, sources are designated uniformly, but still with some minor differences.
It is customary to draw electrical circuits from left to right, that is, the same way as writing text. However, this rule is not always followed, especially by radio amateurs. But, nevertheless, this rule should be adopted and applied in the future.
A galvanic cell or one battery, no matter “finger”, “pinky” or tablet type, is designated as follows: two parallel lines of different lengths. A longer dash indicates the positive pole – plus “+”, and a shorter one – minus “-”.
Also, for greater clarity, battery polarity signs may be indicated. The galvanic cell or battery has a standard letter designation G.
However, radio amateurs do not always adhere to such encryption and often instead G write a letter E, which means that this galvanic cell is a source of electromotive force (EMF). The EMF value may also be indicated next to it, for example 1.5 V.
Sometimes, instead of a picture of the power supply, only its terminals are shown.
A group of voltaic cells that can be recharged repeatedly, battery. In the drawings of electrical circuits they are designated similarly. Only between the parallel lines is a dotted line and a letter designation is used G.B.. The second letter just means “battery”.
Designation of wires and their connections on diagrams
Electrical wires perform the function of combining all electronic elements into a single circuit. They act as a “pipeline” - they supply electronic components with electrons. Wires are characterized by many parameters: cross-section, material, insulation, etc. We will deal with installation flexible wires.
On printed circuit boards, conductive paths serve as wires. Regardless of the type of conductor (wire or track), in the drawings of electrical circuits they are designated in the same way - a straight line.
For example, in order to light an incandescent lamp, it is necessary to supply voltage from the battery using connecting wires to the light bulb. Then the circuit will be closed and a current will begin to flow in it, which will cause the filament of the incandescent lamp to heat up until it glows.
The conductor should be denoted by a straight line: horizontal or vertical. According to the standard, wires or live paths can be depicted at an angle of 90 or 135 degrees.
In branched circuits, conductors often intersect. If an electrical connection is not formed, then a dot is not placed at the intersection.
Common wire designation
In complex electrical circuits, in order to improve the readability of the diagram, the conductors connected to the negative terminal of the power source are often not shown. Instead, they use signs indicating the negative wire, which is also called generally th or weight or chassis or s earth.
Next to the grounding sign, especially in English-language circuits, the inscription GND is often written, abbreviated from GRAUND - Earth.
However, you should know that the common wire does not have to be negative; it can also be positive. It was especially often mistaken for the positive common wire in old Soviet circuits, which predominantly used transistors p— n— p structures.
Therefore, when they say that the potential at some point in the circuit is equal to some voltage, this means that the voltage between the indicated point and the “minus” of the power supply is equal to the corresponding value.
For example, if the voltage at point 1 is 8 V, and at point 2 it is 4 V, then you need to install the positive probe of the voltmeter at the corresponding point, and the negative probe to the common wire or negative terminal.
This approach is quite often used, since it is very convenient from a practical point of view, since it is enough to indicate only one point.
This is especially often used when setting up or adjusting radio-electronic equipment. Therefore, learning to read electrical circuits is much easier by using potentials at specific points.
Conventional graphic designation of radio components
The basis of any electronic device is radio components. These include LEDs, transistors, various microcircuits, etc. To learn how to read electrical circuits, you need to have a good knowledge of the conventional graphic symbols of all radio components.
For example, consider the following drawing. It consists of a battery of galvanic cells G.B.1 , resistor R1 and LED V.D.1 . The conventional graphic designation (UGO) of the resistor looks like a rectangle with two terminals. In the drawings it is indicated by the letter R, followed by its serial number, for example R1 , R2 , R5 etc.
Since an important parameter of a resistor, in addition to resistance, is , its value is also indicated in the designation.
The LED UGO has the shape of a triangle with a line at its apex; and two arrows, the tips of which are directed from the triangle. One terminal of the LED is called the anode, and the second is called the cathode.
An LED, like a “regular” diode, passes current in only one direction - from the anode to the cathode. This semiconductor device is designated V.D., and its type is indicated in the specification or in the description of the circuit. The characteristics of a particular type of LED are given in reference books or “datasheets”.
How to read electrical diagrams for real
Let's return to the simplest circuit consisting of a battery of galvanic cells G.B.1 , resistor R1 and LED V.D.1 .
As we see, the circuit is closed. Therefore, electric current flows in it I, which has the same meaning since all elements are connected in series. Direction of electric current I from the positive terminal G.B.1 through a resistor R1 , Light-emitting diode V.D.1 to the negative terminal.
The purpose of all elements is quite clear. The ultimate goal is to light up the LED. However, so that it does not overheat and fail, the resistor limits the amount of current.
The voltage value, according to Kirchhoff’s second law, may differ on all elements and depends on the resistance of the resistor R1 and LED V.D.1 .
If you measure the voltage with a voltmeter R1 And V.D.1 , and then add the resulting values, then their sum will be equal to the voltage at G.B.1 : V1 = V2 + V3 .
Let's assemble a real device using this drawing.
Adding radio components
Consider the following circuit, consisting of four parallel branches. The first one is just a battery G.B.1, voltage 4.5 V. Normally closed contacts are connected in series in the second branch K1.1 electromagnetic relay K1 , resistor R1 and LED V.D.1 . Further along the drawing there is a button S.B.1 .
The third parallel branch consists of an electromagnetic relay K1 shunted in the opposite direction by a diode V.D.2 .
The fourth branch has normally open contacts K1.2 and boozer B.A.1 .
There are elements here that we have not previously considered in this article: S.B.1 – this is a button without fixing the position. While it is pressed, the contacts are closed. But as soon as we stop pressing and remove our finger from the button, the contacts open. Such buttons are also called tact buttons.
The next element is an electromagnetic relay K1 . Its operating principle is as follows. When voltage is applied to the coil, its open contacts close and its closed contacts open.
All contacts that correspond to the relay K1 , are designated K1.1 , K1.2 etc. The first digit indicates that they belong to the corresponding relay.
Boozer
WITH The next element, previously unknown to us, is the boozer. The buzzer can to some extent be compared to a small speaker. When an alternating voltage is applied to its terminals, a sound of the corresponding frequency is heard. However, in our circuit there is no alternating voltage. Therefore, we will use an active buzzer, which has a built-in alternating current generator.
Passive Boozer – for alternating current .
Active boozer – for direct current.
The active buzzer has a polarity, so you should adhere to it.
Now we can look at how to read an electrical diagram as a whole.
In the original state the contacts K1.1 are in a closed position. Therefore, current flows through the circuit from G.B.1 through K1.1 , R1 , V.D.1 and returns again to G.B.1 .
When the button is pressed S.B.1 its contacts close and a path is created for current to flow through the coil K1 . When the relay has received power its normally closed contacts K1.1 open, and normally closed contacts K1.2 are closed. As a result, the LED goes out V.D.1 and a buzzer sound is heard B.A.1 .
Now let's return to the parameters of the electromagnetic relay K1 . The specification or drawing must indicate the series of the relay used, for example H.L.S.‑4078‑ DC5 V. Such a relay is designed for a nominal operating voltage of 5 V. However, G.B.1 = 4.5 V, but the relay has a certain operating range, so it will work well at a voltage of 4.5 V.
To select a buzzer, it is often enough to know only its voltage, but sometimes you also need to know the current. You should also not forget about its type - passive or active.
Diode V.D.2 series 1 N4148 designed to protect elements that open the circuit from overvoltage. In this case, you can do without it, since the circuit is opened by a button S.B.1 . But if it is opened by a transistor or thyristor, then V.D.2 must be installed.
Learning to read circuits with transistors
In this drawing we see VT1 and engine M1 . To be specific, we will use a transistor of the type 2 N2222 who works in .
In order for the transistor to open, you need to apply a positive potential to its base relative to the emitter - for n— p— n type; For p— n— p type you need to apply a negative potential relative to the emitter.
Button S.A.1 with fixation, that is, it retains its position after pressing. Engine M1 direct current.
In the initial state, the circuit is open by contacts S.A.1 . When the button is pressed SA1 multiple paths for current flow are created. The first way is “+” G.B.1 - contacts S.A.1 – resistor R1 – transistor base-emitter junction VT1 – «-» G.B.1 . Under the influence of current flowing through the base-emitter junction, the transistor opens and a second current path is formed - “+” G.B.1 – S.A.1 – relay coil K1 – collector-emitter VT1 – «-» G.B.1 .
Having received power, the relay K1 closes its open contacts K1.1 in the engine circuit M1 . This creates a third path: "+" G.B.1 – S.A.1 – K1.1 – M1 – «-» G.B.1 .
Now let's summarize everything. In order to learn to read electrical circuits, at first it is enough just to clearly understand the laws of Kirchhoff, Ohm, electromagnetic induction; methods of connecting resistors, capacitors; You should also know the purpose of all elements. Also, at first, you should assemble those devices for which there are the most detailed descriptions of the purpose of individual components and assemblies.
My very useful course for beginners will help you understand the general approach to developing electronic devices from drawings, with many practical and visual examples. After completing this course, you will immediately feel that you have moved from a beginner to a new level.
Since you have decided to become a self-taught electrician, then probably after a short period of time you will want to make some useful electrical appliance for your home, car or garden with your own hands. At the same time, homemade products can be useful not only in everyday life, but also made for sale, for example. In fact, the process of assembling simple devices at home is not difficult at all. You just need to be able to read diagrams and use the ham radio tool.
As for the first point, before you start making electronic homemade products with your own hands, you need to learn how to read electrical circuits. In this case, ours will be a good helper.
Among the tools for novice electricians, you will need a soldering iron, a set of screwdrivers, pliers and a multimeter. To assemble some popular electrical appliances, you may even need a welding machine, but this is a rare case. By the way, in this section of the site we even described the same welding machine.
Special attention should be paid to available materials, from which every novice electrician can make basic electronic homemade products with their own hands. Most often, old domestic parts are used in the manufacture of simple and useful electrical appliances: transformers, amplifiers, wires, etc. In most cases, novice radio amateurs and electricians just need to look for all the necessary tools in a garage or shed in the country.
When everything is ready - the tools have been collected, spare parts have been found and minimal knowledge has been obtained, you can proceed to assembling amateur electronic homemade products at home. This is where our small guide will help you. Each instruction provided includes not only a detailed description of each stage of creating electrical appliances, but is also accompanied by photo examples, diagrams, as well as video lessons that clearly show the entire manufacturing process. If you do not understand some point, you can clarify it under the entry in the comments. Our specialists will try to advise you in a timely manner!