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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Conditional graphic symbols in the schemes adopted in the Radio magazine. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Beginner radio amateur We will talk about such an important part of the article as the electrical and structural diagrams of the described device. To begin with, it is desirable to draw a diagram with a ballpoint pen using a ruler and stencils. Of course, you can use drawing tools and ink, but this is more laborious and hardly advisable. Of course, the scheme can also be made in electronic form, but in this case, the style and size of the conventional graphic symbols (hereinafter, for brevity - UGO) of the elements must be the same as indicated in the figures. Schemes should be executed taking into account resolution requirements: in the scale adopted in the magazine, the resolution should be at least 300 dpi (300 dpi). Schematic files are in .bmp or .tif format.
When drawing up a device diagram, one should adhere to the generally accepted rule: the input is on the left, the output is on the right. Failure to comply with this rule forces the editor to rebuild the circuit, and this is fraught with circuit errors and, in addition, will lead to renumbering of elements, which can also generate errors (especially if the article also contains a printed circuit board drawing). The UGOs of the most common elements in the diagrams and their sizes on a scale of 1:1 (in the magazine - 1:2, that is, half as much) are shown in the figures. The features of the application of some of them will be discussed later, and now a few more words about the general requirements for circuits. Near each element (preferably from above or to the right), its reference designation (R1, R2 ..., C1, C2, etc.) should be indicated. Elements must be numbered from left to right - from top to bottom, for example, like this: R1 R4 R7 R9 R2 R5 R3 R6 R8 R10... Next to the UGO of resistors and capacitors, their ratings are affixed in the generally accepted way. Resistance up to 999 ohms is indicated in ohms without a unit designation, from 1 to 999 kOhm - in kiloohms (they use the abbreviated designation - the letter "k"), from 1 MΩ and above - in megaohms (denoted by the letter "M"). So, the value of 2,2 in the diagram means 2,2 ohms; 330 - 330 Ohm; 1,2 k - 1,2 kOhm; 3,6 M - 3,6 MΩ. Capacitance up to 9 pF is indicated in picofarads without a unit designation, and starting from a value of 999 pF - in microfarads (the letters "mk" are used). The nominal 10 means 000 pF; 5,1 - 5,1 pf; 430 - 430 9100 pf; 9 µ - 100 µF; 0,01 microns - 0,01 microfarads, etc. For oxide capacitors (and sometimes for other types of capacitors, if it is important to pay attention to this parameter), the nominal voltage is indicated by connecting it through the multiplication sign (for example, 470 microns x 470 V). It is desirable to indicate the nominal value of the main parameter for inductors, especially industrial ones (for example, unified chokes DP, DPM, etc.). Inductance up to 999 μH is indicated in microhenry (designation on the diagrams - μH), from 1 to 999 mH - in millihenry (mH), from 1 H and above - in henry (H). Inside the UGO of constant resistors, the dissipation power is indicated, near the UGO of diodes, transistors, microcircuits and some other elements (optocouplers, acoustic heads, digital indicators, pointer meters) - their full designation (with a letter index), and at the outputs of microcircuits and contacts of detachable connectors (plugs and sockets) - their numbers. In addition, next to the UGO of the measuring device, it is desirable to indicate the limiting values \u0b\u100bof the measured value (for example, XNUMX ... XNUMX μA). To facilitate the repetition and adjustment of structures, it is desirable to indicate on the diagram the alternating voltages on the secondary windings of the power transformers, the operating modes of transistors and microcircuits (near their terminals) for direct current, and waveforms of signals at characteristic points of the device. Near the UGO elements used as controls (variable resistors, switches, etc.), connections (plug-in connectors, sockets, clamps) and indicators (incandescent lamps, LEDs, sound emitters, etc.), indicate inscriptions and signs explaining their functional purpose in the device. Well, now - about the features of the use of UGO of some elements in the circuits. Regulation signs (an inclined line with an arrow for capacitors of variable capacity, the same line with a notch at the upper end for trimmer capacitors, trimmers of inductors and an inclined line with a break at the bottom for non-linear resistors - thermistors, varistors, etc.), as well as signs photoelectric effect (oblique arrows pointing from left to top - down to right in the UGO of a photoresistor, photodiode, etc. devices) and optical radiation (oblique arrows pointing from left to bottom - up to right in the UGO of LEDs) should not change their orientation when turning the main symbol to any angle. In other words, the symbol, for example, of a diode in the UGO of an LED can be depicted horizontally, vertically, with the cathode to the left, right, up, down (as convenient for building a circuit), but the arrows of optical radiation in all cases should be directed from it up to the right. A dash perpendicular to the line-symbol of the cathode in the UGO of the zener diode, and a symmetrical notch at the end of the cathode symbol in the UGO of the voltage-limiting diode have a kind of "attachment": for any orientation of these UGOs, they turn along with them, like "glued". They retain the "binding" to the main symbol when turning the UGO and slashes indicating the power dissipation of the resistor is less than 0,5 W. The output lines of the emitter and collector in the UGO of a bipolar transistor (outside the circle symbolizing its case) can be placed both perpendicular to the base output line and parallel to it - in some cases this allows you to "compact" the circuit, make it more compact. A break in the electrical connection line going to the base of such a transistor, as well as to the symbols of the gate, source and drain of the field-effect transistor, is allowed at a distance of at least 5 mm from the circumference-body (on a scale of 1: 1). The number of semicircles that make up the symbols of the inductor included in the oscillatory circuit and the throttle is set to four, and in the symbols of the windings of an asynchronous electric motor - three. In coupling coils and transformer windings, their number is not standardized and can be any (if necessary). A bold dot at one of the conclusions indicates the beginning of the winding. Signs characterizing the principle of operation of the sound transducer can be made not only in the UGO of microphones, but also in the UGO of a telephone, loudspeaker head, in this case their dimensions are increased accordingly. If it is necessary to depict the components of the optocoupler (radiation source and receiver) in different places of the circuit, the body symbol is broken (a semicircle is left for each of the parts, ending in short segments of straight lines), and the sign of optical interaction (two arrows parallel to the long side of the body) is replaced by signs photoelectric effect and optical radiation (oblique arrows, as in UGO photo and LED). Positional designations of the radiation source and receiver are built on the basis of the positional designation of the optocoupler (for example, LED - U1.1, photothyristor - U 1.2). The same is done with the spaced method of depicting an electromagnetic relay (when its winding and contacts are shown in different places of the circuit for ease of construction): the contacts are assigned a designation consisting of the positional designation of the relay and the conditional number of the contact group (for example, relay K1 may have contact groups K1.1. 1.2, K1.3, K1.1, etc.). The sections of switches, switches (for example, SA1.2, SA1.1, etc.), blocks of variable capacitors (C1.2, C1.1, etc.), double, triple and quad variable resistors are numbered in the same way (R1.2,RXNUMXmt.d.). To simplify the schemes, the merging of electrical communication lines into one so-called group communication line, which is depicted as a thickened line, is often used. In the immediate vicinity of the entry points to the group line, they are usually numbered. Instead of numbers, you can use the letter designations of the signals, sometimes this makes it easier to read the diagram. The minimum distance between adjacent lines extending from the group line in different directions must be at least 2 mm (on a scale of 1:1). The lines emerging from the end of the group communication line are depicted as lines of normal thickness. Connections made with a shielded wire are distinguished by a dashed circle, from which a line is drawn connecting it to the common wire (case) of the device or ground. If it is necessary to show shielded connections in a group of lines running in parallel, a shield icon is placed above them and a line is drawn from it with arrows indicating which connections are placed in the shielding braid. In some cases (for example, to reduce interference), the wires are twisted. The twist sign (an oblique line with serifs in opposite directions) covers all communication lines made in this way. Lines connecting elements that are far from each other, especially in cases where it is difficult to depict the connections they make, are cut off, and the ends of the remaining segments are provided with arrows near which addresses are indicated (letters of the Russian or Latin alphabet, positional designations of elements) that unambiguously restore not connection shown. For example, when the communication line between the resistors R5, R6 and the capacitor C42 is broken, the arrow connected to the resistors says "K C42", and the arrow coming from the capacitor says "K R5, R6". A few words - about UGO chips of digital and analog technology. They are built on the basis of rectangles called fields. UGOs of the simplest devices (for example, logical elements) consist only of the main field; in more complex ones, one or two additional ones are added to it, located on the left and right. In the main field, inscriptions and signs are placed indicating the functional purpose of the element or microcircuit, in the additional field - the so-called labels explaining the purpose of the pins. The field width is determined by the number of characters (including spaces). The minimum width of the main field - 10, additional - 5 mm. The distance between the terminals, as well as between the terminal and the horizontal side of the UGS or the boundary of the zone separating one terminal from the others, is 5 mm (all dimensions on a 1:1 scale). At the points of connection of the output lines, special signs (pointers) are depicted that characterize their special properties: a small circle (inversion), a slash ("/" - direct, "\" - inverse dynamic input), a cross (an output that does not carry logical information e.g. power output). In the right field of the UGO of digital microcircuits, signs built on the basis of a rhombus are sometimes placed. If it is provided with a dash on top, this means that this pin is connected to the collector of a p-n-p transistor, the emitter of an n-p-n transistor, the drain of a p-channel field effect transistor, or the source of an n-channel transistor. If the named electrodes belong to transistors of the opposite structure or devices with a channel of the opposite type, the dash is placed below. A diamond with a dash inside indicates a pin with a so-called high output impedance (Z-state). In order not to clutter up the circuit with the power supply circuits of digital microcircuits, the corresponding conclusions are usually not shown in their UGO, but in order to make it clear which conclusions the power is supplied to, in the places where it comes from (the power supply output, the circuit to which the external source is connected), they place arrows with addresses, for example, "To pin 14 DD1, DD2; pin 10 DD3, DD4; pin 16DD5, DD6". And, finally, about UGOs used in structural and functional diagrams. Their basis is a square, which indicates the functional purpose of the device. Most of the UGOs shown in the figures are simple and clear, and only a few require explanation. Specifically, the generator symbol. In addition to the letter G, in its designation, you can indicate the frequency range (one sinusoid - low frequencies, two - sound, three - high), a specific frequency value (for example, 500 kHz), the shape of oscillations in the form of a simplified oscillogram, the presence of frequency stabilization, etc. d. Two or three sine symbols are also used to indicate the purpose of the filters, but here they represent frequency bands. For example, in the UGO of the high-pass (HPF) and low-pass (LPF) filters, two sinusoids symbolize oscillations of frequencies lying above and below the crossover frequency (in the first case, the lower sinusoid is crossed out, therefore, the device passes signals with a frequency above the cutoff frequency, in the second - the upper , which indicates the transmission of signals below this frequency). In the UGO of the band-pass and notch filters, there are three sinusoids. As in the previous case, the frequency bands indicated by sinusoids that are not crossed out are skipped: if the upper and lower sinusoids are crossed out, it is a bandpass filter, and if the middle one is a notch filter. Amplifiers are indicated either by a square with a triangle - the amplification symbol - inside, or by an equilateral triangle (the top with the output pin - the direction of signal transmission). The second UGO is preferable: it is more visual and also allows you to indicate in it, for example, the number of cascades of the device (it is inscribed in a triangle). UGO delay lines instead of symbols of lumped and distributed parameters may contain a numerical value of the delay time, as well as signs indicating the method of transformation: piezoelectric (in the form of a quartz resonator symbol), magnetostrictive (two horizontally located semicircles).
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