This article describes a simple audio frequency generator, in other words, a buzzer. The circuit is simple and consists of only 5 elements, excluding the battery and the button.
Description of the scheme:
R1 sets the offset to VT1 base. And with the help of C1, feedback is carried out. The speaker is a VT2 load.
Assembly:
So, we need:
1) Complementary pair of 2 transistors, that is, one NPN and one PNP. Almost any low-power will do, for example KT315 and KT361. I used what was at hand - BC33740 and BC32740.
2) Capacitor 10-100nF, I used 47nF (marking 473).
3) Trimmer resistor about 100-200 kOhm
4) Any low-power speaker. Headphones can be used.
5) Battery. Almost anything is possible. Finger, or crown, the difference will be only in the frequency of generation and power.
6) A small piece of foil-clad fiberglass, if you plan to do everything on the board.
7) Button or toggle switch. I used a button from a Chinese laser pointer.
So. All details are collected. Let's start making the board. I made a simple surface mount board mechanically (that is, with a cutter).
So, everything is ready for assembly.
First, we mount the main components.
Then we solder the power wires, a battery with a button and a speaker.
The video shows the operation of the circuit from a 1.5V battery. A trimmer resistor changes the oscillation frequency
List of radioelements
| Designation | A type | Denomination | Quantity | Note | Shop | My notebook |
|---|---|---|---|---|---|---|
| VT1 | Bipolar transistor | KT315B | 1 | Into notepad | ||
| VT2 | Bipolar transistor | KT361B | 1 | Into notepad | ||
| C1 | Capacitor | 10-100nF | 1 | Into notepad | ||
| R1 | Resistor | 1-200 kΩ | 1 |
The entire frequency range generated by the device is divided into four subranges: 10-100 Hz, 100-1000 Hz, 1000 Hz-10 kHz, and 10-100 kHz.
Rice. 25. The scheme of the audio frequency generator.
The device operates on four transistors and is powered by three KBS-L-0.50 batteries connected in series. The current consumed by the device from the power supply is 10 ma at an output voltage of 8 V. The output impedance of the device is 1 kΩ.
The diagram of the device is shown in Fig. 25. The generator is assembled according to the cxetae of a T-shaped bridge on transistors T1 and T2. Positive feedback between the collector of the transistor T1 and the base of the transistor T2 is carried out through the diode D1, on the electrodes of which a fixed voltage of 0.6 V is maintained, due to which the current characteristic of the transistor T1 is more linear.
Feedback between the collector of transistor T2 and the emitter of transistor T1 is through resistor R7. The voltage across diode D2 determines the operating point of both transistors.
The generator frequency is roughly changed by the inclusion of capacitors C1-C4 and C5-C8 in the T-shaped bridge by switches P1 and P1b. The frequency is smoothly controlled by the resistor R13.
To reduce the influence on the generator of the tunable devices connected to it, an output stage is assembled on the T3 transistor, connected according to the emitter follower circuit.
Details. Common parts are used for the generator. Switch P4 - single-board, 4 positions. Resistor R4, type SPO-0.5, R3 - SPO-2. Capacitors C1-C8 type MB or BGM. Diodes D1-D3 types D9, D2, D101. Microammeter for a current of 500 μA with an internal resistance of 1,500 ohms.
Rice. 26. External view of the generator.
The generator parts are mounted on a PCB board (Fig. 26) and the front panel of the device. The body and the panel are made of sheet duralumin 1.5-2 mm thick. External dimensions of the case are 210X100x55 mm.
The external view of the device is shown in Fig. 27.
The tuning of the generator begins with the selection of diodes D1 and D2, the forward voltage drop across which should be 0.5-0.6 V. With such diode voltages, the current consumed by the device from the battery at the maximum output voltage should be 8-12 mA. If the current is less, then the device does not generate. Generation is achieved with a variable resistor R4.
Rice. 27. Location of parts in the generator housing.
In order for each subband to overlap the indicated frequencies, it is necessary to select the capacitors included in the bridge so that by switching the generator with the P1 switch from one subband to the adjacent one, the frequency changes exactly 10 times.
First, switch P1 must be set to position 1, when capacitors C4 and C8 are included in the bridge. In this case, the generator should cover the frequency range from 10 to 100 Hz. You can adjust such a frequency section by changing the capacitances of the capacitors C1 and C8. Then the switch is set to position 2 (capacitors C7 and C2 are connected). Now the generator frequency should be changed by the resistor R13 from 100 to 1000 Hz. If it does not correspond to this range, you need to change the capacitances of capacitors C2 and C7.
The other sub-bands of the generator are also tuned, multiplying the frequencies by 100 and 1000, respectively.
To calibrate the device, you need a control audio frequency generator, according to which a homemade device is tuned. Headphones are connected to both generators. When the frequencies of the generators are equal, the sound of one current is heard in the phones (zero beats between the frequency of the reference and homemade generators).
The instrument scale is drawn on thick white paper and covered with transparent varnish.
Sound frequency generator circuit operation description |
Sound frequency generator circuit on transistors
Two transistors - field-effect VT1 and bipolar VT2 - are connected according to the scheme of a composite repeater having a small gain and repeating the phase of the input signal at the output. Deep negative feedback (NF) through resistors R7, R8 stabilizes both the gain and the mode of the transistors.
But for the appearance of generation, a positive feedback is also needed from the output of the amplifier to its input. It is carried out through the so-called Wien bridge - a chain of resistors and capacitors R1 ... R4, C1 ... C6. The Wien bridge weakens both low (due to the increasing capacitance of capacitors C4 ... C6) and high (due to the shunting action of capacitors C1 ... C3). At the central frequency, those settings, approximately equal to 1 / 271RC, its gain is maximum, and the phase shift is zero. Generation occurs at this frequency.
By changing the resistance of the resistors and the capacitance of the bridge capacitors, the generation frequency can be changed over a wide range. For ease of use, a tenfold frequency range is selected with a double variable resistor R2, R4, and the frequency ranges are switched (Sla, Sib) by capacitors C1 ... C6.
To cover all audio frequencies from 25 Hz to 25 kHz three ranges are enough, but if you wish, you can add a fourth, up to 250 kHz (this is done by the author). By choosing a few large capacitances of capacitors or resistances of resistors, you can shift the frequency range down, making it, for example, from 20 Hz to 200 kHz.
The next important point in the design of a sound generator is the stabilization of the output voltage amplitude. For simplicity, the most ancient and reliable method of stabilization is used here - with the help of an incandescent lamp. The fact is that the resistance of the lamp filament increases by a factor of almost 10 when the temperature changes from a cold state to full incandescence! A small indicator lamp VL1 with a cold resistance of about 100 ohms is included in the OOS circuit. It shunts the resistor R6, while the OOS is small, the PIC prevails and generation occurs. As the oscillation amplitude increases, the lamp filament heats up, its resistance increases, and the OOS increases, compensating for the PIC and thereby limiting the growth of the amplitude.
A step divider is turned on at the generator output voltage across resistors R10 ... R15, allowing to obtain a calibrated signal with an amplitude of 1 mV to 1 V... The divider resistors are wired directly to the pins of a standard 5-pin audio jack. The generator receives power from any source (rectifier, accumulator, battery), often from the same source from which the device under test is powered. The supply voltage across the transistors of the generator is stabilized by the R11, VD1 chain. It makes sense to replace resistor R11 with the same incandescent lamp as VL1 (indicator telephone, in "pencil" version) - this will expand the limits of possible supply voltages. Consumption current - no more 15 ... 20 mA.
Parts of almost any type can be used in the generator, but special attention should be paid to the quality of the double variable resistor R2, R4. The author used a fairly large precision resistor from some outdated equipment, but double resistors from the volume or tone controls of stereo amplifiers are also suitable. Zener diode VD1 - any low-power, for stabilization voltage 6.8 ... 9 V.
When adjusting, one should pay attention to the smoothness of the generation of the approximately in the middle position of the engine of the tuning resistor R8. If its resistance is too low, the generation may stop in some positions of the frequency setting knob, and if it is too large, there may be a distortion of the sinusoidal waveform - limitation. You should also measure the voltage at the collector of the transistor VT2, it should be equal to about half the voltage of the stabilized power supply. If necessary, select the resistor R6 and, in extreme cases, the type and instance of the YT1 transistor. In some cases, the inclusion of an electrolytic capacitor in series with the incandescent lamp VL1 with a capacity of at least 100 uF("Plus" to the source of the transistor). In conclusion, the resistor R10 sets the signal amplitude at the output 1 in and calibrate the frequency scale using a digital frequency meter. It is common for all ranges.
A feature of this sound generator circuit is that everything in it is built on an ATtiny861 microcontroller and an SD memory card. The Tiny861 microcontroller consists of two PWM generators and, thanks to this, is able to generate high-quality sound, and in addition, it is able to control the generator with external signals. This audio frequency generator can be used to test the sound of high quality speakers or in simple amateur radio DIY such as an electronic bell.
Sound frequency generator circuit on the timer |
The audio frequency generator is built on the popular KP1006VI1 timer microcircuit (almost according to the standard scheme. The output signal frequency is about 1000 Hz. It can be adjusted in a wide range by adjusting the ratings of the C2 and R2 radio components. The output frequency in this design is calculated by the formula:
F = 1.44 / (R 1 + 2 × R 2) × C 2
The output of the microcircuit is not capable of providing high power, therefore a power amplifier is made on the field-effect transistor.
Chip and field key audio frequency generator
Oxide capacitor C1 is designed to smooth out the ripple of the power supply. The SZ capacitance connected to the fifth terminal of the timer is used to protect the control voltage output from interference.
Any stabilized one with an output voltage of 9 to 15 volts and a current of 10 A will do.
The world around us is full of sounds. In the city, these are mainly sounds associated with the development of technology. Nature gives us more pleasant sensations - the singing of birds, the sound of the surf, the crackling of a campfire on a camping trip. Often, some of these sounds need to be reproduced artificially - to imitate, simply out of desire, or based on the needs of your technical modeling circle, or when staging a performance in a drama club. Consider the descriptions of several sound simulators.
Intermittent siren sound simulator |
Let's start with the simplest design, this is a simple siren sound simulator. There are single-tone sirens, emitting a sound of one tone, intermittent when the sound gradually rises or falls, and then interrupts or becomes monotone, and two-tone, in which the tone of the sound periodically changes abruptly.
On transistors VT1 and VT2, a generator is assembled according to the scheme of an asymmetrical multivibrator. The simplicity of the generator circuit is explained by the use of transistors of different structures, which made it possible to do without many of the details necessary to build a multivibrator on transistors of the same structure.
Siren sound simulator - circuit on two transistors
Oscillations of the generator, which means the sound in the dynamic head, appear due to the positive feedback between the collector of the transistor VT2 and the base of VT1 through the capacitor C2. The tonality of the sound depends on the capacity of this capacitor.
When the switch SA1 applies the supply voltage to the sound generator in the head, there will still be no bias voltage at the base of the transistor VT1. The multivibrator is in standby mode.
As soon as the SB1 button is pressed, the capacitor C1 begins to charge (through the resistor R1). The bias voltage at the base of the transistor VT1 begins to increase, and at a certain value, the transistor opens. The sound of the desired key is heard in the dynamic head. But the bias voltage increases and the tone smoothly changes until the capacitor is fully charged. The duration of this process is 3 ... 5 s and depends on the capacitance of the capacitor and the resistance of the resistor R1.
It is worth releasing the button - and the capacitor will begin to discharge through the resistors R2, R3 and the emitter junction of the transistor VT1. The tone of the sound changes smoothly, and at a certain bias voltage at the base of the transistor VT1, the sound disappears. The multivibrator returns to standby mode. The duration of the capacitor discharge depends on its capacity, the resistance of the resistors R2, R3 and the emitter junction of the transistor. It is selected such that, as in the first case, the tonality of the sound changes within 3 ... 5 s.
In addition to those indicated in the diagram, other low-power silicon transistors of the corresponding structure with a static current transfer coefficient of at least 50 can be used in the simulator. large static transmission ratio. Capacitor C1 - K50-6, C2 - MBM, resistors - MLT-0.25 or MLT-0.125. Dynamic head - with a power of 0, G ... 1 W with a voice coil with a resistance of 6 ... 10 Ohm (for example, head 0.25GD-19, 0.5GD-37, 1GD-39). Power source - battery "Krona" or two series-connected batteries 3336. Power switch and button - of any design.
In standby mode, the simulator consumes a small current - it depends mainly on the reverse current of the transistor collector. Therefore, the contacts of the switch can be closed for a long time, which is necessary, say, when using the simulator as an apartment bell. When the contacts of the SB1 button are closed, the current consumption rises to about 40 mA.
Looking at the circuit of this simulator, it is easy to notice the already familiar node - a generator assembled on transistors VT3 and VT4. The previous simulator was assembled according to this scheme. Only in this case, the multivibrator does not work in standby mode, but in normal mode. For this, the bias voltage from the divider R6R7 is applied to the base of the first transistor (VT3). Note that transistors VT3 and VT4 have swapped places compared to the previous circuit due to a change in the polarity of the supply voltage.
So, a tone generator is assembled on transistors VT3 and VT4, which sets the first tone of the sound. On the transistors VT1 and VT2, a symmetrical multivibrator is made, thanks to which a second tone of sound will be obtained.
It happens like this. During operation of the multivibrator, the voltage on the collector of the transistor VT2 is either present (when the transistor is closed), or disappears almost completely (when the transistor is opened). The duration of each state is the same - about 2 s (i.e., the pulse repetition rate of the multivibrator is 0.5 Hz). Depending on the state of the transistor VT2, the resistor R5 shunts either the resistor R6 (through the resistor R4 connected in series with the resistor R5) or R7 (through the collector-emitter section of the transistor VT2). The bias voltage at the base of the VT3 transistor changes abruptly, so the sound of one or the other tonality is heard from the dynamic head.
What is the role of capacitors C2, SZ? They allow you to get rid of the influence of the tone generator on the multivibrator. If they are absent, the sound will be somewhat distorted. Capacitors are included in anti-series because the polarity of the signal between the collectors of transistors VT1 and VT2 changes periodically. A conventional oxide capacitor under such conditions works worse than the so-called non-polar one, for which the polarity of the voltage at the terminals does not matter. When two polar oxide capacitors are switched on in this way, an analog of a non-polar capacitor is formed. True, the total capacitance of the capacitor becomes half that of each of them (of course, with the same capacitance).
Siren sound simulator on four transistors
This simulator can use the same types of parts as in the previous one, including the power supply. For supplying the supply voltage, either a conventional switch with a latching position is suitable, as well as a push-button switch, if the simulator will work as an apartment bell.
Some of the parts are mounted on a printed circuit board (Fig. 29) made of one-sided foil-clad fiberglass. Mounting can be hinged, performed in the usual way - using mounting racks for soldering the leads of parts. The board is placed in a suitable housing in which the dynamic head and power supply are installed. The switch is placed on the front wall of the case or attached near the entrance door (if there is already a bell button there, its terminals are connected by conductors in isolation with the corresponding circuits of the simulator).
As a rule, the simulator, mounted without errors, starts working immediately. But if necessary, it can be easily adjusted to obtain a more pleasant sound. So, the tonality of the sound can be somewhat lowered by increasing the capacitance of the capacitor C5 or increased by decreasing it. The range of the tone change depends on the resistance of the resistor R5. The duration of the sound of a particular key can be changed by selecting capacitors C1 or C4.
So you can say about the next sound simulator, if you listen to its sound. Indeed, the sounds emitted by the dynamic head are reminiscent of exhaust emissions typical of a car, tractor or diesel locomotive engine. If the models of these machines are equipped with the proposed simulator, they will immediately come to life.
According to the scheme, the engine operation simulator is somewhat reminiscent of a single-tone siren. But the dynamic head is connected to the collector circuit of the transistor VT2 through the output transformer T1, and the bias and feedback voltages are fed to the base of the transistor VT1 through the variable resistor R1. For direct current, it is connected with a variable resistor, and for the feedback formed by a capacitor, it is connected with a voltage divider (potentiometer). When you move the slider of the resistor, the frequency of the generator changes: when the slider is moved down the circuit, the frequency increases, and vice versa. Therefore, a variable resistor can be considered an accelerator that changes the speed of the "engine" shaft, and hence the frequency of sound exhausts.
Engine sound simulator - two-transistor circuit
For the simulator, transistors KT306, KT312, KT315 (VT1) and KT208, KT209, KT361 (VT2) with any letter indices are suitable. Variable resistor - SP-I, SPO-0.5 or any other, possibly smaller in size, constant - MLT-0.25, capacitor - K50-6, K50-3 or other oxide, with a capacity of 15 or 20 μF for a nominal voltage not below 6 V. Output transformer and dynamic head - from any small-sized ("pocket") transistor receiver. One half of the primary winding is used as winding I. The power source is a 3336 battery or three 1.5 V cells connected in series.
Depending on where you will use the simulator, determine the dimensions of the board and case (if you intend to install the simulator not on the model).
If, when you turn on the simulator, it will work unstable or there is no sound at all, swap the terminals of the capacitor C1 - with a positive terminal to the collector of the transistor VT2. By selecting this capacitor, you can set the desired limits for changing the number of revolutions of the "engine".
Cap ... drip ... drip ... - sounds are heard from the street when it is raining or drops of melting snow fall from the roof in spring. These sounds have a calming effect on many people, and according to some, even help to fall asleep. Well, perhaps you will need such a simulator for the phonogram in your school drama club. It will take only a dozen parts to build the simulator.
A symmetrical multivibrator is made on the transistors, the loads of the arms of which are high-resistance dynamic heads BA1 and BA2 - from them sounds of "drops" are heard. The most pleasant "drop" rhythm is set with the variable resistor R2.
Drop sound simulator - two-transistor circuit
For reliable "start" of the multivibrator at a relatively low supply voltage, it is desirable to use transistors (they can be of the MP39 - MP42 series) with the largest possible static current transfer coefficient. Dynamic heads should be 0.1 - 1 W with a 50 - 100 Ohm voice coil (for example, 0.1GD-9). If there is no such head, you can use DEM-4m capsules or similar ones with the indicated resistance. Capsules with higher impedance (for example, from TON-1 headphones) will not provide the required sound volume. The rest of the details can be of any type. The power source is a 3336 battery.
The parts of the simulator can be placed in any box and mounted on its front wall dynamic heads (or capsules), a variable resistor and a power switch.
When checking and adjusting the simulator, you can change its sound by selecting a wide range of constant resistors and capacitors. If in this case a significant increase in the resistances of the resistors R1 and R3 is required, it is advisable to install a variable resistor with a large resistance - 2.2; 3.3; 4.7 kOhm to provide a relatively wide range of droplet frequency regulation.
Bouncing ball sound simulator circuit |
Want to hear a steel ball bounce off a ball bearing on a steel or cast iron plate? Then assemble the simulator according to the diagram shown in fig. 32. This is a variant of an asymmetrical multivibrator used, for example, in a siren. But unlike the siren, the proposed multivibrator does not have circuits for adjusting the pulse repetition rate. How does the simulator work? It is necessary to press (briefly) the SB1 button - and the capacitor C1 will be charged to the voltage of the power source. After releasing the button, the capacitor will become the source of power to the multivibrator. While the voltage on it is high, the volume of the "beats" of the "ball" reproduced by the dynamic head BA1 is significant, and the pauses are relatively long.
Bouncing Ball Sound Simulator - Transistor Circuits
Gradually, as the capacitor C1 is discharged, the character of the sound will also change - the volume of the "beats" will begin to decrease, and the pauses will decrease. In conclusion, a characteristic metallic bounce will be heard, after which the sound will stop (when the voltage across the capacitor C1 falls below the transistor opening threshold).
Transistor VT1 can be any of the MP21, MP25, MP26 series, and VT2 - any of the KT301, KT312, KT315 series. Capacitor C1 - K.50-6, C2 - MBM. The dynamic head is 1GD-4, but another will do, with good mobility of the diffuser and its possibly larger area. The power source is two 3336 batteries or six cells 343, 373 connected in series.
Parts can be mounted inside the simulator body by soldering their leads to the button and dynamic head leads. Batteries or cells are attached to the bottom or sides of the case with a metal bracket.
When adjusting the simulator, the most characteristic sound is achieved. To do this, select the capacitor C1 (it determines the total duration of the sound) in the range of 100 ... 200 μF or C2 (the duration of the pauses between "hits" depends on it) within 0.1 ... 0.5 μF. Sometimes for the same purposes it is useful to choose a transistor VT1 - after all, the work of the simulator depends on its initial (reverse) collector current and the static current transfer coefficient.
The simulator can be used as an apartment bell by increasing the volume of its sound. The easiest way to do this is to add two capacitors to the device - СЗ and С4 (fig. 33). The first of them directly increase the volume of the sound, and the second get rid of the sometimes occurring tone drop effect. However, with such a refinement, the "metallic" tint characteristic of a real bouncing ball is not always preserved.
Transistor VT3 can be any of the GT402 series, resistor R1 - MLT-0.25 with a resistance of 22 ... 36 ohms. In place of VT3, transistors of the MP20, MP21, MP25, MP26, MP39 - MP42 series can operate, but the sound volume will be somewhat weaker, although much higher than in the original simulator.
Surf sound simulator circuit |
By connecting a small set-top box to the amplifier of a radio, tape recorder or TV, you can get sounds that resemble the noise of the sea surf.
A diagram of such a simulator attachment is shown in Fig. 35. It consists of several units, but the main one is the noise generator. It is based on a silicon Zener diode VD1. The fact is that when applied to the zener diode through a ballast resistor with a large resistance of a constant voltage exceeding the stabilization voltage, the zener diode begins to "break through" - its resistance drops sharply. But due to the insignificant current flowing through the zener diode, such a "breakdown" does no harm to it. At the same time, the zener diode, as it were, goes into the noise generation mode, the so-called "shot effect" of its pn junction appears, and a chaotic signal consisting of random oscillations whose frequencies can be observed (of course, with the help of a sensitive oscilloscope) lie in a wide range.
It is in this mode that the zener diode of the attachment works. The ballast resistor mentioned above is R1. Capacitor C1, together with a ballast resistor and a zener diode, provides a signal of a certain frequency band, similar to the sound of surf noise.
Sea surf sound simulator circuit on two transistors
Of course, the amplitude of the noise signal is too small to be fed directly to the amplifier of the radio device. Therefore, the signal is amplified in a cascade on the transistor VT1, and from its load (resistor R2) is fed to the emitter follower, made on the transistor VT2, it allows you to eliminate the influence of the subsequent stages of the attachment on the operation of the noise generator.
From the load of the emitter follower (resistor R3), the signal is fed to a stage with a variable gain, assembled on a transistor VT3. Such a cascade is needed in order to be able to change the amplitude of the noise signal supplied to the amplifier, and thereby simulate the rise or fall of the "surf" loudness.
To accomplish this task, a transistor VT4 is connected to the emitter circuit of the transistor VT3, to the base of which the signal from the control voltage generator is fed through the resistor R7 and the integrating chain R8C5 - a symmetrical multivibrator on transistors VT5, VT6. At the same time, the resistance of the collector-emitter section of the transistor VT4 changes periodically, which causes a corresponding change in the gain of the stage on the transistor VT3. As a result, the noise signal at the output of the stage (across the resistor R6) will periodically rise and fall. This signal is fed through the capacitor C3 to the XS1 connector, which is connected during operation of the set-top box to the input of the amplifier used.
The duration of the pulses and the repetition rate of the multivibrator can be changed by resistors R10 and R11. Together with the resistor R8 and the capacitor C4, they determine the duration of the rise and fall of the control voltage supplied to the base of the transistor VT4.
All transistors can be the same, the KT315 series with the highest possible current transfer ratio. Resistors - MLT-0.25 (MLT-0.125 is also possible); capacitors Cl, C2 - К50-3; SZ, C5 - C7 - K.50-6; C4 - MBM. Capacitors of other types are suitable, but they must be designed for a rated voltage not lower than that indicated in the diagram.
Almost all parts are mounted on a circuit board (Fig. 36) made of foil-clad material. Place the board in a housing of suitable dimensions. The XS1 connector and the XT1, XT2 clamps are fixed on the side wall of the case.
The set-top box is powered from any DC source with a stabilized and adjustable output voltage (from 22 to 27 V).
As a rule, it is not required to set up a set-top box. It starts working immediately after power is applied. It is not difficult to check the operation of the set-top box with the help of high-impedance headphones TON-1, TON-2 or other similar ones included in the XS1 “Output” connector sockets.
The nature of the sound of the "surf" is changed (if necessary) by selecting the supply voltage, resistors R4, R6, as well as by shunting the XS1 connectors with a capacitor C7 with a capacity of 1000 ... 3000 pF.
And here is another such sound simulator, assembled according to a slightly different scheme. It has an audio amplifier and a power supply, so this simulator can be considered a complete design.
The noise generator itself is assembled on a VT1 transistor according to the so-called superregenerator circuit. It is not very easy to understand the operation of a super-regenerator, therefore we will not consider it. Understand only that this is a generator in which the excitation of oscillations occurs due to the positive feedback between the output and the input of the stage. In this case, this connection is carried out through a capacitive divider C5C4. In addition, the super-regenerator is excited not constantly, but by flashes, and the moment of the appearance of flares is random. As a result, a signal appears at the output of the generator, which is listened to as noise. This signal is often referred to as "white noise".
The surf sound simulator is a more complex version of the circuit
The DC super-regenerator operating mode is set by resistors Rl, R2, R4. The choke L1 and the capacitor C6 do not affect the operating mode of the stage, but they protect the power circuits from the penetration of a noise signal into them.
The L2C7 contour defines the "white noise" frequency band and allows you to get the largest amplitude of the "noise" oscillations that are detected. Then they go through the low-pass filter R5C10 and the capacitor C9 to the amplifier stage, assembled on the transistor VT2. The supply voltage to this stage is not supplied directly from the GB1 source, but through the stage assembled on the VT3 transistor. This is an electronic key that periodically opens with pulses arriving at the base of the transistor from a multivibrator assembled on transistors VT4, VT5. During periods when the transistor VT4 is closed, VT3 opens, and the capacitor C12 is charged from the GB1 source through the collector-emitter section of the transistor VT3 and the trimmer R9. This capacitor is a kind of battery that feeds the amplifier stage. As soon as the transistor VT4 opens, VT3 closes, the capacitor C12 is discharged through the trimmer R11 and the collector-emitter circuit of the transistor VT2.
As a result, on the collector of the transistor VT2 there will be a noise signal, modulated in amplitude, that is, periodically increasing and decreasing. The rise time depends on the capacitance of the capacitor C12 and the resistance of the resistor R9, and the fall - on the capacity of the specified capacitor and the resistance of the resistor R11.
The modulated noise signal is fed through the capacitor JV to an audio frequency amplifier based on transistors VT6 - VT8. At the input of the amplifier there is a variable resistor R17 - a volume control. From its engine, the signal is fed to the first amplifier stage, assembled on a VT6 transistor. This is a voltage amplifier. From the load of the stage (resistor R18), the signal goes through the capacitor C16 to the output stage - a power amplifier made on transistors VT7, VT8. A load is included in the collector circuit of the transistor VT8 - the dynamic head BA1. The sound of "sea surf" is heard from it. Capacitor C17 attenuates the high-frequency, "sibilant" components of the signal, which somewhat softens the timbre of the sound.
About the details of the simulator. Instead of the KT315V (VT1) transistor, you can use other transistors of the KT315 series or the GT311 transistor with any letter index. The rest of the transistors can be any of the MP39 - MP42 series, but with the highest possible current transfer ratio. To obtain greater output power, the VT8 transistor is desirable to use the MP25, MP26 series.
Choke L1 can be ready-made, such as D-0.1 or another.
Inductance 30 ... 100 μH. If it is not there, you need to take a rod core with a diameter of 2.8 and a length of 12 mm from ferrite 400NN or 600NN and wind a turn on it to a turn of 15 ... 20 turns of the PEV-1 wire 0.2 ... 0.4. It is advisable to measure the resulting inductance of the choke on a reference device and, if necessary, select it within the required limits by decreasing or increasing the number of turns.
The L2 coil is wound on a frame with a diameter of 4 and a length of 12 ... 15 mm made of any insulating material with a PEV-1 wire 6.3 - 24 turns with a tap from the middle.
Fixed resistors - MLT-0.25 or MLT-0.125, tuning resistors - SPZ-16, variable - SPZ-Sv (it is with a SA1 litany switch). Oxide capacitors - К50-6; C17 - MBM; the rest are KM, K10-7 or other small-sized ones. The dynamic head - with a power of 0.1 - I W with the highest possible resistance of the voice coil (so that the transistor VT8 does not overheat). The power source is two 3336 batteries connected in series, but the best runtime results will be obtained with six 373 cells connected in the same way. Suitable, of course, is the power supply option from a low-power rectifier with a constant voltage of 6 ... 9 V.
Details of the simulator are mounted on a board (Fig. 38) made of foil-coated material with a thickness of 1 ... 2 mm. The board is installed in a case, on the front wall of which a dynamic head is attached, and a power source is placed inside. The size of the case is largely dependent on the size of the power supply. If the simulator is used only to demonstrate the sound of the sea surf, the power source can be a Krona battery - then the dimensions of the case will drastically decrease, and the simulator can be mounted in a case from a small-sized transistor radio receiver.
Set up a simulator like this. Disconnect the resistor R8 from the capacitor C12 and connect to the negative power wire. Having set the maximum sound volume, the resistor R1 is selected until the characteristic noise ("white noise") in the dynamic head is obtained. Then the connection of the resistor R8 with the capacitor C12 is restored and the sound in the dynamic head is listened to. By moving the engine of the trimmer resistor R14, the most reliable and pleasant listening frequency of the "sea waves" is selected. Further, by moving the slider of the resistor R9, the duration of the rise of the "wave" is set, and by moving the slider of the resistor R11, the duration of its decay.
To get a high volume of the "sea surf", you need to connect the extreme terminals of the variable resistor R17 with the input of a powerful audio amplifier. The best experience can be obtained by using a stereo amplifier with external speakers operating in monaural mode.
Rain noise sound simulator simple circuit |
If you want to listen to the beneficial effects of the measured noise of rain, forest or the surf. These sounds are relaxing and soothing.
Rain noise sound simulator - circuit based on operational amplifier and counter
The rain noise generator is made on the TL062 microcircuit, which includes two operational amplifiers. Then the generated sound is amplified by transistor VT2 and fed to the SP speaker. For greater compliance with the HF sound spectrum, it is cut off by a capacitor C8, which is controlled by a field-effect transistor VT1, which essentially operates as a variable resistance. Thus, we get automatic control of the tone of the simulator.
The CD4060 counter has a timer with three turn-off time delays: 15, 30 and 60 minutes. The VT3 transistor is used as a generator power switch. By changing the values of resistance R16 or capacitance C10, we get different time intervals in the operation of the timer. By changing the value of the resistor R9 from 47k to 150k, you can change the speaker volume.
Every man to his own taste. As for sounds, mankind has also determined itself and is well endowed with the blessings of songwriters and extractors of musical pleasures. Hearing is not developed in everyone, but no one has doubts about the universal innate ability to publish something unpleasant for others, although this is a delusion.
The proposed Horrible Sound Generator (GUZ) "gives birth" to children aged 4 ... 12 years. The impudently destructive meaning of the game is to select the most dissonant combination of frequencies.
The combination of several frequencies can always be assessed on a scale excellent - terrible. The development of any perception is determined by its working range. Refined aesthetes and connoisseurs of toilet folklore are equally boring in communication. Lovers of sweet and savory are lost for cooking. And what your dog thinks about the great French perfumery is better not to translate from a dog.
From the experience of coexistence with the GUZ.
This is a sport: the purpose of the competition has no practical meaning.
This is a game: even on the nerves.
This is creativity: you need talent or at least ability to win.
This is labor: the skill is developing.
This is pedagogy: and the latter will be the first.
This is the rest: for the mind and body as they are not required.
This is science: The maxignus has not yet been found.
This mess: it ends at the same time as the batteries.
With all the variety of approaches to the production of unpleasant sounds, they can be reduced to two structural schemes. In any case, there is a set of separate generators of audio frequency, the selection of frequencies of which and achieve the desired impression. Then you can either combine the signals from the outputs of the generators into one and use a common channel of amplification and sound reproduction, or each of the generators has its own amplifier and sound emitter.
Simple horror sound generator
Synthesizer
In the simplest case, it is permissible to use simple pulse generators as individual sound generators. For joint work, it is desirable to unify the characteristics of their output signals. Here they are meanders. A mixture of these signals somewhat improves the hearing of their interacting harmonics.
Two oscillator channels are organized here, each of which consists of a frequency-tunable oscillator on logic elements and a frequency divider in half on a one-bit counter from a D-flip-flop. After such a divisor, we always have a pure meander.
The electrical diagram shows that there are significant differences in the performance of functionally identical generators. This is a necessary measure when assembling them from a set of logic elements of one microcircuit case. Experience shows that when oscillators of the same circuit are tuned to close frequencies, what is called clumping of frequencies, pulling, self-synchronization occurs. Then the frequency regulator of one of them ceases to operate and copies the setting of the other in a large range.
If two generators obtain equal frequencies with significantly different values of the timing elements (here R2, PR1, C1 and R3, PR2, C2), then there is no such danger.
Although the microcircuits work well in the range of supply voltages of 3.5 ... 15V, here they are powered through a parametric stabilizer (4.7V) on the reference diode VD1. Its ballast is resistors R4, R5. Moreover, together with C3, they form a two-sided T-shaped noise filter.
The frequency of generators based on logic elements is highly dependent on the supply voltage. In autonomous devices, galvanic cells "sit down" over time, and without stabilization, the obtained vileness will improve.
The indicated input voltages +7.8 ... + 10V correspond to a standard seven-cell galvanic battery of international standard size 6F22, known in our country by its first (40 years ago!) Name "Krona" or a sealed cylindrical storage battery 7D-0.125.
If you have other sources of stable voltage, you can safely use them, excluding the elements VD1, R3 and R4. It is better to leave C3.
Acoustics
The decibels adorn the horror. And scare yourself, and generously share them with others. There are two ways. Or we use amplifiers and acoustics of the existing household equipment, or we make a completely autonomous device.
The first path is simple, quick to execute, acoustically efficient, and ties a group of young experimenters to one place with a connecting cord, leaving the rest of the world for adults. The second way is good if adults are united by something stationary (table, TV, sofa), and everything that interferes is removed the farther beyond the horizon, the better.
All music centers have inputs for connecting external stereo signal sources (AUX). There are similar inputs on computer sound cards (AUX, LINE). All TVs are equipped with audio inputs (mostly monaural for now). In all cases, the signal from one output is fed to the left channel, from the second to the right. Actually "horror" spatial separation of sounds does not interfere. Moreover, not to the aesthetic experiences of the neighbors behind the wall.
The output level of pulse signals from the synthesizer is higher than that required for a conventional low-frequency amplifier (Uinp = 0.2 ... 1V, Rinp = 20 ... 100kΩ), so there should be no problems with pairing. You just need to remember that you need to supply an alternating signal without a constant component to the ULF input, i.e. through a blocking capacitor.
Pairing circuit for one channel... The RP5 trimmer matches the output level of the synthesizer signal to the input level of a specific amp. Set it so that the volume control of the amplifier controls it optimally.
A stand-alone generator needs its own audio amplifier. We select them from the required output power. We combine signals into one on a simple resistive mixer with the ability to separately adjust the output sound levels for each of the generator channels.
About customization
Frequency adjustment from low to high frequencies is carried out by changing the resistance of the tuning resistor. To get a comfortable feeling of uniform frequency change from the angle of rotation of the knob, its characteristic should be logarithmic. For domestic elements, it corresponds to the letter B at the end of the name. You can improve (complicate) the tuning by dividing the audio range into two or three sub-bands.
For fair group play (much appreciated!), Preset memory is essential. Even fixing only two settings is enough for flawless competition with any number of players according to the Olympic system with the elimination of the loser. One of the settings stores the most impressive sound combination at the moment, and the second is used for creative exploration of the applicant. By moving the switch, you can always compare both sounds and choose the worst one. If the challenger wins, his settings are fixed, and the next attempt comes with the knobs of the knocked down from the pedestal.
Victory is coveted and should not be tempted by the opportunity to tweak the sound of the leader a little bit. The settings must be protected from nimblers. In this case, the simplicity of the electronics leaves this function to the case designer. All variants of mechanical interlocking or difficulty in accessing the controls of the stored settings are suitable.
A good one has proven itself, for example, the rod protection, where trimming resistors with a short slot that do not protrude above the front panel of the device are used as regulators, and there is only one pair of rearranged recessed handles.
Synthesizer of terrible sounds... The body made of aluminum profile with side visors protects the handles well from accidental touches, and the location of the controls related to different settings on opposite sides makes attempts to knock off the leader's settings very obvious. In the middle position of the A / V control switch, the power is removed.
Two settings in one of the generators. In the "off" switch position, a separate switch group SA1 (not shown) turns off the power.
Design
Synthesizer print layout... The power supply stabilizer (R3, R4, C3, VD1), which is required only in some cases, is not shown. Adjustment resistors RP1 and RP2 are installed separately.
Mesh pitch 1.25 mm.
