Novice schemes sensory musical instruments. Musical instruments do it yourself scheme and design. Sensor-controlled electronic violin

Source: Journal « Technics – Young people » , №3 for 1960. Author: B. Oorlov (engineer). The article supplemented a small note about Emiton from the same magazine, but from number 1 for 1946.

"Effective tools due to a wide range of height, strength and richness of the timbre are expanding the creative possibilities of not only the composer, but also a performer musician. And such qualities as expressive, beautiful sound, in conjunction with singer, the richness of the timbres and the availability of equipment, ensure their mass distribution and turn them into a serious factor in the penetration of high musical culture into life. " (From the statements of the People's Artist of the USSR Academician B. V. Asafyeva)

A bit of history

Are we surprised by the rich and diverse expressive opportunities of the modern orchestra? No, they seem so natural now. After all, musical instruments and technique of the game were improved by centuries. We rarely think about the fact that the composer of the XVII century did not have a half of the tools that are available from the composer of our days. Meanwhile, even relatively recently, the music was performed only with extreme shades of the sound of the sound: either quiet or loud. Composers did not know what opportunities would be in charge of a gradual increase or weakening of the soundness. And when in the middle of the 18th century, the Italian composer and conductor Iomelly first resorted to these effects, the impression was stunning: when the strength of the sound of the sound, the listeners, holding his breath, rose friendly from their places ...

The brass instruments remained very imperfect. And such tools like trombone, tube, chest, saxophone, have not yet been invented. With their appearance, about a middle of the last century, the composition of the symphony orchestra, which remained mainly to the present day.

Since then, work on the design of new tools froze. Further enrichment of the orchestra sound palette occurred only by improving the instruments and the growth of performing skills.

However, there are quite a few flaws in the designs of classical musical instruments: in many respects they are now far from perfect. In the arsenal of orchestral paints, a modern composer sometimes does not find everything necessary for the incarnation of his creative ideas. Each group of tools - copper, wooden, string, drums - to some extent appreciated and is limited in their capabilities, as painting would be limited if the paints of the artist were characterized only by strokes of a certain form.

Single and expressive brook tools are poorly dressed, and loud copper - sediments. The entire range of sounds in height is not a number of rather narrow sections attached to individual orchestra tools.

The sound palette of the orchestra is intermittent, its condition resembles periodic system Mendeleev elements at the time when the gaps in her ranks were still not filled.

And the timbre - the color of the sound? This property for which we can easily find out the tools, even if they are not visible to us, it remains unchanged not from each of them. When playing in different registers, the timbres of the pipe, trombone, a fagoth, as if the shades of the paint of the artist changed as the brush on the canvas. Is it possible to imagine a picture with bright colors only in the middle of the canvas, at the top - white, and at the bottom - muted or dirty? How much energy should be spent the composer to master the disorderly and cunning colors of the orchestra!

Not less barriers to skill and performer. Only many years of persistent and persistent training, usually begin in orphanage, give him a complete and all-resting power over the tool. This requires the principle of obtaining sound: mechanical oscillation of string or air column in the pipe. It is quite clear that in the age of automation and electronics the development of musical instruments could not already go to the old mechanical path.

The first steps of electricians

Great technical discoveries: Telegraph, telephone, radio - gave the creators of new musical instruments - this material body of music is completely new tools. We call them now radio-electronic. There was an area of \u200b\u200bfascinating creative cooperation of radio engineers, acoustics and musicians. Work and this area turned out to be fruitful: one after another began to appear a variety of tools designs.

At first, they were very complex, imperfect and depressing cumbersome. So, one of the first electrical organs - - weighed 200 tons. He, of course, remained only with laboratory experience. It was not brought to the practical implementation and tool of his compatriot Lee DE Foresta, the inventor of the three-electrode lamp.

The first electrical displacement tool that have gained wide fame throughout the world was. Remembering the first steps of the new tool, he says:

- To me, physics and radio engineering, who also gained a musical education in the Leningrad Conservatory, it seemed that the use of radiologist in the music, which in the twenties was the same news as the atomic reactor now, opens the tempting prospects. By creating your own tool, I wanted to make the sound that the performer obeyed directly, without an intermediate mechanical environment - as the orchestra obeyed the conductor. In this tool, the sound is extracted unusually, the free movement of the hand in the space near a small metal stick - antenna. For the first time I demonstrated it in 1921 at the VIII electrical congress. Then I performed on the Termenvelox (so suggested calling a new tool one of the musical critics) several works, Saint-Sanas and folk music.

Thermmallox uses two high-frequency generators. When the hand is moving near the antenna rod, the capacity of the oscillating circuit changes, and therefore the frequency of one of the generators. The sound frequency required for music execution is obtained as a high frequency difference excited by generators.

Following the Termenvelox there was a number of power tools. it ilston Composer I.G. Ilsarova, close to the device and a method for extracting sound to thermmallox, Sonar Sonar engineer N.Sanianva, Violin V.A.Gurova, keyboard tools: equodin Constructions A.A. Wrodyna, Compane and D. Simonov and others.

In the postwar years, new designs of electrical tools were created, which can already be considered serious rivals of conventional type tools. Among them emiriton A.A.Ivanova and A.V. Rimsky-Korsakov, "B-9" A.A. Wrodyna, the original multi-voice tool of the Riga radio amateur L.Vingris. But the miniature electronic piano of the composer Ilsarov is especially interesting. They contain only six electronic lamps (without amplifier), but can work on two lamps.

How are they arranged?

What are electromusical instruments?

Despite the large differences in the designs, the schemes of such tools are created according to the general principle. The heart of the tool is the tone generator similar to a radio transmitter generator. In most cases, it works on electronic lamps and excites electrical oscillations of a very complex shape.

Why do you need to generate such electrical oscillations? The fact is that the composition of musical sounds is far from simple. They fold from air fluctuations with different frequencies and intensities. In total oscillation, several components. One of them has the lowest frequency. It is called the main tone, the rest - overtones. For periodic oscillations, what musical sounds are, the frequencies of overtones are multiple the frequency of the main tone, that is, superior to it for an integer time. These are the so-called harmonics. In the sound spectrum of the instrument, the grads depends largely. For example, 11 harmonics participate in the creation of clarinet. The sound, very poor, seems to be neuropric and low, and when the harmonic is not at all, it produces the simplest impression on hearing, and therefore is called simple, or clean, tone.

Complicated electrical oscillations excited by the tone generator contain a large number of harmonics. Therefore, a wide variety of timbres, which can approach the timbres of conventional tools, and can be easily obtained on an electrical displacement tool. The tool keys provide contacts that include in the generator circuits electrical resistances of various values. This allows you to get sounds in all registers of the music scale, from the lowest to the highest.

In the next block of an electrical instrument, the nature of the occurrence of sound and its attenuation is regulated. These processes strongly affect the timbre and can completely transform it. Further electricity It is sent to the so-called enzyme chains, where some harmonics are strengthened. In conventional tools, this amplification gives a housing that serves as an acoustic resonator and emphasizes the sound of individual frequencies in the sound spectrum. Then the electric current enters the amplifier equipped with a pedal volume control. This allows you to change the power of sound as much as possible, if desired, gradually increasing or relaxing it. Sound source is a dynamic reproducer.

Synthetic sound

In addition to the design of new performing instruments, there is another interesting area of \u200b\u200belectrical inspection - the creation of electronic devices designed to work composers. The principle on which they are based is very simple. Any musical sound can be represented as some set of pure tones. On the contrary, having a fairly large number of their number, you can get sounds of any heights, volume, timbre. Working with a similar device, the composer becomes like a breeder of sounds. Connecting them in a variety of combinations, it creates unprecedented sound fruit - hybrids, the receipt of which is technically not achievable for a conventional orchestra. Since such an apparatus uses the idea of \u200b\u200ba connection, the synthesis of simple sounds to obtain complex, then it is called the synthesizer.

Research in this area has begun back in the 30s. There were a lot of inventors. They used cinema features: after all, on the film, the sound is written in the form of a well-noticeable wavy line. When combining records of various clean tones into one sound schedule, painted from hand, they managed to get sounds with peculiar and interesting timbresses. However, this method did not get much spread, since the drawing of sound is a very painstaking and difficult matter.

The work in this area continued the candidate of Technical Sciences E.A. Murzin, quite recently ending many years of work to create an electronic music synthesizer. The designer called him - in honor of the wonderful Russian composer Alexander Nikolayevich Scriabin, in the museum of which the device is now installed.

ANS provides composer 576 pure tones overlapping 8 octave music scales. The control device allows you to connect these tones in any combination. Their generation is made by an optical mechanical way. The device consists of four identical blocks, one of which is highlighted on the color tab.

Working with this amazing machine, the composer writes music not notes, but special frequency stamps. He draws marks on opaque glass - "score". At the same time, the composer does not need to wait for the orchestra to go and fulfill his work. He can listen to music already in the process of its writings, introducing the necessary corrections immediately.

Very diverse the synthesis of timbres, quickly performed by a set of control device handles. This allows you to create fundamentally new sounds on Anse, which cannot be obtained on conventional tools.

On Anse, it is possible to get complex sounds that differ from each other in height not only on 1/12 part of the octave, as on the piano, and at any distance until 1/72 of its part when they become for hearing almost indistinguishable.

To get separate shades, noise and pride, the composer can work with "score", as an artist, retouching and painting the lumeks. He always sees a visual image - a light code that corresponds to the written musical phrase. It helps his work. It can also adjust the volume of each of the 16 tool registers (by the number of photocells), the overall volume and pace of execution. The composer does this at the second stage of his work, as if turning into a conductor. Here it uses two more special handles. Finally adjusted by them shades of sound, he records music on a magnetic film.

The tab shows the scheme of the musical synthesizer ANS, the design of E.A. Murzin. The main thing here is an optical-mechanical generator of pure sound tones. It consists of four identical blocks. In each block, the following details: 1 - light source; 2 - condenser for the collection of light in a flat beam; 3 - a rotating disk, covered with rows of dark strips, smoothly passing into transparent gaps; 4 - gearbox binding disk with an electric motor; 5 - flywheel.

Under the influence of the rotation of the disk, the light beam becomes intermittent, "modulated". The states "light" - "Darkness" smoothly alternate. The speed of these alternations is evenly increasing from the center and the edge of the disk.

The mirror 6 directs the modulated flow of light through the lens 7 onto a flat glass - "score" 8, covered on top of non-dry black paint. If the paint is in any places to remove, the modulated light will fall into cylindrical lenses 9 and the prisms 10, and then in the photocells 11 (they are only 16). Strengthening the resulting AC gives sound in dynamics.

All four generator blocks give one solid strip of modulated light on the glass. The gear ratios of gearboxes are selected so as to obtain along this strip alternation of light and shadow with the same frequency change law, as in the scale of the piano keyboard sounds. For the convenience of the composer, the keyboard image is applied along the light strip. The encoder moves in the same direction - the device for removing paint from the surface of the glass - "scores". Its cutters can be made on the glass of the lumen of the desired width and length, which depends on the volume and duration of the sound. The entire encoder has 16 incisors. They allow us to combine the main tone in one sound along with any of the 15 of its harmonic, giving it the necessary timbre at the request. Rotating a small flywheel, the composer can move the glass - "score" and immediately listen to the written musical phrases.

The ANS synthesizer has already received recognition and high assessment of many composers and acoustics specialists. "The widespread development of a mechanical recording in modern life," wrote the composer I.G. Bolldirev, - gives all the grounds to believe that it is possible to use the Ans apparatus in artistic practice in the field of cinema, radio, television and gramzapsy - in all cases where the composer concealed Effects are easier and more accurate can be reproduced on this machine than on conventional tools. "

Working with a new tool has already shown his richest opportunity. To fully master them, the composer needs to work quite a few, mastering the unusual sound formation system. But he will be rewarded by a hundredfold - after all, the ANS synthesizer provides him with expressive opportunities, many times superior to the usual orchestra.

Let's try to look at tomorrow electricians. There are quite a few musical miracles. One of them is small tools made on semiconductors. Light and comfortable, they will not refuse the sound in the quality of the sound. Simple keyboard Make them available to a non-professional amateur. Such tools can cost very inexpensively. And it will not be experimental samples. Anyone who wants to purchase a similar tool will be able to freely buy it and shop.

The technique of today allows such ideas about which the musicians of the past could only dream. It's and light music and music with smooth change The timbres, and spatial sound effects. And the tools such as termenvox will create "dance music". After all, the ballet artist may not be one of the movement of the hand, but also to all the dance "compose" the music accompanying this dance. And many more musical miracles will allow electronielectronics. They are now even difficult to foresee.

Emiriton

Emiriton- This is a single-haired electric musical instrument with a range of 6 1/2 octave. This tool is not automatic; On it, as well as on a piano or violin, you need to learn to play. On Emiriton you can reach a wide variety of sounds: imitate the violin, cello, clarinet, gobyu, saxophone and many brass tools. Moreover, even the sounds specific on the timbre, like a drum battle, the root of the aircraft, the singing of birds and vowels of human voices, are reproduced by Emiiton.

It can be performed on it any complex musical works.

Emiriton A. A. Ivanov and A. V. Roman-Korsakov was constructed.

Externally, the tool resembles a fesharmonium without keys. Instead, an electric neck is arranged. This is a long row, over which the elastic contact tape is stretched.

A tube generator is placed in the EMITON housing, the timbre controller, filter and amplifier. The lamp generator works according to a diagram giving a variety of harmonic oscillations. By pressing the vulture in the right place, the performer includes a certain part of the rosostat in the generator chain and thereby sets a certain voltage to the lamp grid. Each voltage corresponds to its oscillation frequency.

Changing the color of sound - timbre - reach a special device that changes the shape of the oscillations. Having passed through it, the oscillations enter the electric forward. The filter helps to emphasize the desired frequency of the musical range, that is, to obtain the so-called formants of the sound.

The Contractor manages this tool using appropriate handles and a small keyboard located near the grid. Sound volume is adjustable to a foot pedal. From the electric oscillation filter through the amplifier enter the reproducer located at the bottom of the tool housing.

Rich in various colors, Emiriton can give the sound of any volume. This is its great advantage compared to conventional musical instruments, the volume of the sound of which is very limited.

Schemes of the simplest electronic devices for beginner radio amateurs. Simple electronic toys and devices that can be useful for home. Schemes are built on the basis of transistors and do not contain deficient components. Imitors of birds votes, musical instruments, light music on LEDs and others.

Trell Generator Solovya

Solovna Trell Generator, made on an asymmetric multivibrator, is collected according to the scheme shown in Fig. 1. A low-frequency oscillating circuit formed by telephone caps and capacitor SZ is periodically excited by pulses produced by a multivibrator. As a result, sound signals are formed, resembling nightingale trills. In contrast to the previous scheme, the sound of this simulator is not controlled and, therefore, more single one. The timbre of sound can be selected by changing the capacitance of the Conde Torah SZ.

Fig. 1. Hallway trill generator, device diagram.

Electronic imitator singing canary

Fig. 2. Scheme of the electronic imitator of singing canary.

The electronic imitator of singing canary is described in the book B.S. Ivanova (Fig. 2). It is also based as a asymmetric multivibrator. The main difference from the previous scheme is the RC chain included between the multivibrator transistors databases. However, this simple innovation allows you to radically change the nature of the generated sounds.

Simer Kryakanya Duck

The timber chamber simulator (Fig. 3), proposed by E. Bri-Gineevich, as well as other schemes of simulators, implemented on an asymmetrical multivibrator [P 6 / 88-36]. A telephone capquil BF1 is included in one multivibrator shoulder, and in another - successively connected LEDs HL1 and HL2.

Both loads work alternately: the sound is published, the LEDs break out - the "duck" eyes. The sound tonality is selected by the R1 resistor. The device switch is desirable to perform on the basis of the magneto-controlled contact, can be self-made.

Then the toy will be turned on when making a disguised magnet to it.

Fig. 3. The diagram of the timber chamber of the duck.

Generator "Noise Rain"

Fig. four. Schematic scheme Generator "Noise of Rain" on transistors.

Generator "Noise of Rain", described in Monograph V.V. Matskevich (Fig. 4), produces sound impulses, alternately reproduced in each of the telephone capsules. These clicks remotely resemble a drop of raindrops on the windowsill.

In order to give an accident to the character of the drop of drops, the scheme (Fig. 4) can be improved by entering, for example, sequentially with one of the resistors of the field of field transistor. The field of field transistor will be an antenna, and the transistor itself will be a controlled variable resistor, the resistance of which will depend on the electric field strength near the antenna.

Electronic drum prefix

Electronic drum - a diagram generating a sound signal of the corresponding sound when touched to the sensor contact (Fig. 5) [MK 4 / 82-7]. The generation operating frequency is within 50 ... 400 Hz and is determined by the parameters of the RC elements of the device. Such generators can be used to create the simplest electrical tool with sensory control.

Fig. 5. Concept of electronic drum.

Sensor-controlled electronic violin

Fig. 6. Electronic violin diagram on transistors.

The electronic "violin" of the sensor type is represented by the scheme shown in the B.S. book Ivanova (Fig. 6). If you make a finger to the sensory contacts of the "violin", the pulse generator is turned on, made on the VT1 and VT2 transistors. A sound, the height of which is determined by the magnitude of which is determined by the key. electrical resistance The portion of the finger applied to the touchscrew plates.

If it is stronger to press a finger, its resistance is reduced, the height of the sound tone will increase accordingly. The finger resistance also depends on its humidity. By changing the degree of pressed finger to contacts, you can perform a simple melody. The initial frequency of the generator is set by the R2 potentiometer.

Electromusical instrument

Fig. 7. Scheme of a simple homemade electrical tool.

Cultibrator-based electrical tool [V.V. Matskevich] produces electrical impulses of a rectangular shape, the frequency of which depends on the resistance value of Ra - Rn (Fig. 7). With this generator, you can synthesize the sound gamut within one or two octaves.

The sound of rectangular shape signals is very reminded by organ music. Based on this device, a music box or shaman can be created. To do this, the disk rotated by the handle or the electric motor is applied around the circle contacts of various lengths.

These contacts are attacked by pre-selected RA resistors, which determine the frequency of pulses. The length of the contact strip sets the duration of the sound of a particular note when sliding overall moving contact.

Simple colorwoman on LEDs

Colorubic support device with multi-colored LEDs, the so-called "flasher" will decorate the musical sound additional effect (Fig. 8).

The input signal of the sound frequency by the simplest frequency filters is divided into three channels, conditionally referred to as low-frequency (red luminous LED); mid-frequency (LED green. Glow) and high-frequency (yellow LED).

The high-frequency component is highlighted by a chain C1 and R2. The "mid-frequency" signal component is allocated by a sequential type LC-filter (L1, C2). As a coil of the filter inductance, you can use the old universal head from the tape recorder, or the winding of a small-sized transformer or choke.

In any case, when adjusting the device, the individual selection of capacitors C1 - SZ will be required. The low-frequency component of the sound signal is freely passed through the R4 circuit, the SZ on the Database of the VT3 transistor, which controls the luminescence of the "red" LED. The currents of the "high" frequency are cut by a capacitor of the SZ, because It has extremely small resistance for them.

Fig. 8. Simple color-chill installation on transistors and LEDs.

Electronic toy "Guess the color" on LEDs

The electronic machine is designed to guess the color of the inclusion in the LED (Fig. 9) [B.S. Ivanov]. The device comprises a pulse generator - a multivibrator on VT1 and VT2 transistors associated with a trigger on VT3 transistors, VT4. A trigger, or a device with two stable states, is switched alternately after each of the pulses that came to its input.

Accordingly, the multi-colored LEDs included in each of the trigger shoulders are displayed alternately. Since the generation frequency is sufficiently high, the flashing of LEDs when the pulse generator is turned on (pressing the SB1 button) merges into a continuous glow. If you release the SB1 button, the generation stops. The trigger is installed in one of the two possible stable states.

Since the frequency of the trigger switching was large enough, to predict in advance, in which condition is the trigger, it is impossible. Although each rule has exceptions. Playing is invited to determine (predict), which color will appear after the next generator launch.

Or it is proposed to guess which color will turn around after the button is released. With a large set of statistics, the likelihood of an equilibrium, equilibious lighting of LEDs should come closer to 50:50. For a small number of attempts, this ratio may not be performed.

Fig. 9. Schematic diagram of electronic toys on LEDs.

Electronic toy "Who has better reaction"

Electronic device allowing to compare the speed of the reaction of two subjects [B.S. Ivanov], can be collected according to the scheme shown in Fig. 10. The first indicator is displayed - the LED of the one who first presses the "its" button.

At the heart of the trigger device on VT1 and VT2 transistors. To re-test the reaction speed, the device's power must be disabled briefly with an additional button.

Fig. 10. Schematic diagram of toys "Who is better reaction."

Homemade phototir

Fig. 11. Circuit diagram.

Lighting S. Gordeyev (Fig. 11) allows not only to play, but also to train [p 6/83-36]. The photocell (photo resistance, photodiode - R3) is directed to a luminous point or a sunny bunny and press the trigger (SA1). Condensor C1 is discharged through a photocell to the input of the pulse generator, working in waiting mode. The telephone cap is sound.

If the laying is inaccurate, and the resistor resistance R3 is large, then the discharge energy is not enough to start the generator. For focusing light needed lens.

Literature: Shustov MA Practical scheme engineering (book 1), 2003.

The keyless electrical tool, the diagram of which is shown in Figure 1 Made on the same K561L7 chip containing four logical elements. The keyboard consists of two blocks of 12 buttons - keys in each. Each block manages one tool voice.
On the elements D1.1 and D1.2, a multivibrator has been made, generating frequencies from 988 Hz to 523 Hz.

Using the buttons of the S2 S13 keys, you can choose such frequencies. 988Hz, 932Hz, 880Hz, 831 Hz, 784Hz, 740Hz. 698Hz, 659Hz, 622 Hz. 587Hz, 554 Hz and 523Hz. This corresponds to the tones: "SI" of the second octave, "Si-Bemol", "La". "La-Beleol", "Salt", "Sol-Beleol", "Fa", "Mi", "Mi-Bemol", "Re". "Reebly" and "before."

The frequency of oscillations at the output of the multivibrator depends on the capacitance of the C2 condenser and the resistance between the input and the output of the D1.1 element. This resistance depends on which of the S2-S13 buttons are pressed, and which of the R2-R25 resistors will be turned on with this button.

Oscillations from the release of a multivibrator via Diode VD1 and the R27 resistor arrive at the amplifier base on the transistor V11, in the collector circuit of which there is a speaker B1.

In the K561LA7 chip there are four logical elements, on the other two, - D1.3 and D1.4 is made by a second multivibrator, which is almost the same as the multivibrator on D1.1 and D1.2, but the capacitor C3 condenser here is more than C2, so The second multivibrator produces tone fluctuations in half the lower than the first.

Oscillations from the release of a multivibrator on D1.3 and D1.4 through the VD2 diode and the R28 resistor, as well as the oscillations of the first multivibrator, are entered on the VT1 transistor database.

It feeds the musical instrument from the battery voltage 9V ("Crohn"). Most parts are located on a small one-sided printed circuit board, a mounting diagram and a scheme for the location of the printed tracks, which are shown in Figure 2.

PCB can be made in any available way. The tracks may look different, for example, be wider or other shape. It is important that the connections were as in the figure and there were no closures between the tracks.

Buttons, switch and speaker are located on the front (top) plastic box panel, which serves as a case.

Buttons can be any type - which you can purchase. It is important that they are closing and without fixing (that is, they are closed while you keep pressed, but how to let go - opens). The speaker is also suitable almost any, but preferably broadband small-sized, for example, such as in pocket receivers. Connecting the power supply, be careful. Since with incorrect polarity of the microcircuit can die.

After installation, carefully check the installation, the location of the parts, the installation of the chip. By setting the chip remember that the key on its package is located near the 1st output or near the end from the side of the 1st and 14th output. That is, if you look at Figure 2, the key will be left.

With errorless installation and serviceable details, the musical instrument is operational immediately after the first inclusion, but that its sound exactly corresponds to a noth row, the resistance is R2-R25 and R30-R53 to choose when the tool is established.

At the same time, you need to use some kind of tuned musical instrument, determining the notes on the hearing, or the frequency measurement of the frequency at the output of the multivibrators (the frequency values \u200b\u200bare indicated at the beginning of the article).

However, it is not necessary to seriously refer to this tool - it is rather a toy than a real musical synthesizer. If all resistors, as well as C2 and C3 capacitors, there will be exactly such denominations, as shown in the diagram, the tool will make sounds close to the sound of the corresponding notes.

For the first time, the scheme of this interesting electronic musical instrument - toys appeared in the magazine "Radio" in 1984, but later (in 2002) she was finalized by I. Nechayev - Added a sensory volume control. It is this modified scheme, despite its respectable age, I want to offer novice radio amateurs. The design of the tool is simple for repetition, quite visual and can become a good toy not only a child, but also, as practice shows, adult. Take a look at the device scheme.

On the elements of DD1.1 and DD1.2, the sound frequency generator is collected, the frequency of which depends on the elements R1, R2 and C1. The feature of the generator is that its frequency can be changed in the lighting intensity - the photoresistor R1 is responsible for it. The higher the illumination of the photoresistor, the lower its resistance and the higher the frequency of the generator. That is why the musical instrument is called the "traffic light". The DD1.3 element is buffer, and DD1.4 in conjunction with the C2 capacitor is the volume control knob.

From the regulator, the signal enters the amplifier collected on the VT1 transistor and emitted by the headphone BF1. So, the sound frequency signal, from the output of the DD1.3 element, comes to a differentiating chain consisting of resistors R3 (it is connected to sensors E1, E2), R4 and C2 condenser. From it, short pulses are fed to the input of the DD1.4 element, the amplifier and play the headphone. At the same time, if the sensors do not touch, the R3 in the operation of the chain does not participate the volume of the sound is minimal.

If you close the sensors with your finger, then the R3 resistor and skin resistance will turn into operation. This will allow the condenser to be charged in pauses between pulses, the stronger the more stronger the sensor with the finger. Due to this, at the output of the element DD1.4, the pulse duration will increase, and the sound volume will increase. Thus, overlapping the sensors with a finger, we will be able to adjust the volume of the sound within certain limits, and changing the illumination of the photoresistor (for example, by turning the device relative to the light source) - the tone frequency. After a small workout, it is quite realistic to play on such a musical instrument a simple melody.

On-site DD1 can work K564L5, K564L7, K561L7, VD1 - KD521A, KD103A, KD503A. Capacitor C3 - any electrolytic operating voltage at no lower than 10 V, the rest are any ceramic. As R1, the photoresistors of FGC-K1, SF2-5, SF2-6 can be used. As emitter bf1 suitable any Phone or dynamic head with resistance not lower than 50 ohms.

If the resistance of the head is lower, then instead of the transistor KT315 will have to put more powerful, for example, KT972 with any letter. The design of the light arbitrary, the sensors are made of a piece of foil fiberglass with a size of 20 x 30 mm. To obtain two sensors along the strip foil cut through, the width of the slot - 0.5 ... 1 mm.

Most often you met musical and electrical tools with keyboards (less often with keyboard) keyboard. There are no keys or buttons in the proposed tool. Its keyboard is made up of two metal plates (Fig. 55) located on the front panel of a small box. The "closure" plates with one or more fingers are achieved by the desired tonality, and an executed melody sounds from the box.

The scheme of an unusual electrical tool is shown in Fig. 56. Transistors VT1, VT2 and the remaining parts are interconnected in such a way that form an asymmetrical multivibrator. FeedbackThe necessary for the occurrence of oscillations is carried out from the VT2 transistor collector to the VT1 base through the C1 capacitor. But on the basis of the transistor VT1 there is no constant offset voltage (relative to the emitter), so the transistor is closed and the multivibrator does not work.

In such a state, the device will be located until the finger touch the Sensors E1 and E2. Then between them turns out to be the resistance of the skin of the finger. A bias voltage will be supplied to the database, and the multivibrator will turn on. In the dynamic head of the VA1, the sound will be heard.

The sound tonality depends on the resistance between the sensors, and it, in turn, is determined by the area of \u200b\u200bthe skin attached to the sensors. In addition, the skin of each person has its own conductivity, and therefore resistance that can be in tens and hundreds of times different from the resistance of the skin of another person. Considering this, the variable resistor R1 is installed in the multivibrator - it compensate for this difference and set the same initial impedance between the E2 sensor and the transistor base VT1. In other words, each performer can "configure" tools under their hands. \\

Working in the first cascade Transistor VT1 - high-frequency, silicon, structures P-P-P. It is impossible to replace it with a low-frequency transistor of the same structure (for example, MP37, MP38), since the multivibrator will start to work immediately after connecting the power supply of the SA1 switch, even if the sensors do not concern. Therefore, you need to install the transistor specified on the diagram or in extreme cases to replace it with CT316A.

Instead of transistor MP42B, MP39B, MP41, MP42A, GT402A is suitable. The last transistor is the most powerful of the listed, the sound will be louder with it. Dynamic head - any, with a capacity of up to 1 W and resistance of the sound coil of a DC up to 10 0m. Good results are obtained, for example, with a head of 0.25GD-19, which is developed by the board and body-casket of the musical instrument.

Variable resistor - SP-I, permanent - MLT-0.25, capacitor - MBM, switch - TW2-1 toggle switch, power source - Battery 3336.

Tool details Place (Fig. 57) from the insulating material.

The tool housing (Fig. 58) can be made of any insulating material, for example plywood 4 mm thick. The bottom cover is removable so that the battery can be changed (it is attached to the metal screw cover).

The front panel cut the slit opposite the diffuser of the dynamic head. From the inside the slit is closed with a loose tissue. Under the variable resistor and turn off

the hole in the front panel is drilled by holes - they are passed on the protruding parts of the specified parts and are fixed on top of nuts. There will be no other mounting fee.

Sensors are a strip of a width of about 10 mm, cut out of copper, brass or tinted from cans. They can be attached to the front panel at a distance 2.. .4 mm from each other. Bend from the inside of the housing ends of the slats are connected by conductors with the corresponding fees. The outer surface of the slats is cleaned to the shine of sandpaper.

After checking the installation and reliability of the paks, feed the power switch to the multivibra-rice. 58. Electrical construction design Install the variable resistor engine

musical instrument _ ____- "____________.

in the leftmost position according to the scheme (in other words, to the position of the minimum resistance) and press the finger at the same time to both touch plates. The sound of a relatively low tonality should appear in the dynamic head. Without releasing the fingers, put the variable resistor engine to another extreme position - the sound tonality will increase.

If there is no sound, close the sensors and achieve its selection of the resistor R2 or R3. The R2 resistor is selected if the sound is barely listened. If it is fully lacking, it is necessary to first close the R3 resistor and make sure the multivibrator is working, and then select the R3 resistor (with a smaller resistance).

Having finished checking and establishing the tool, you can play it. Applying a finger to sensors, set the desired sound tonality by an alternating resistor. Higher pressing the finger to the sensors or applying several fingers to them, change the sound tonality and execute a simple melody. A little training - and you can confidently play on this unusual musical instrument.

To change the boundaries of the tool sound range, you need to pick up the C1 condenser. With an increase in its capacity, the tone height decreases, and when decreasing, it rises.

The tool consumes current from the power source only during touch sensors, the rest of the time the transistors are closed. Therefore, the battery energy is spent economically. It is necessary to replace it, as a rule, after 40.. . 50 hours of the tool.