Simulator of sound effects on programmable ROMs. Simple patterns for beginners. a - fastening pin

The device, the circuit of which is shown in the figure below, produces a complex signal audio frequency, reminiscent of birdsong. The basis for it was a somewhat unusual asymmetrical standby multivibrator, assembled on two bipolar silicon transistors of different conductivities. The power source GB1 (Corundum battery) is constantly connected through connector X1 to the cascade on transistor VT2, which is separated from the first stage on transistor VT1 by a normally open button SB1. A special feature of the device is the presence of three timing circuits, which, in fact, determines the nature of the sound effect. The simulator does not have a general power switch, since the current consumption in standby mode does not exceed 0.1 μA, and this is significantly less than the self-discharge current of the battery.

The device works like this. One has only to press the SB1 button, and capacitor C1 will be charged to the voltage of battery GB1. After releasing the button, the capacitor will power transistor VT1. It will open, and the base current VT2 will flow through its collector-emitter junction, which will also open. Here the RC positive feedback circuit, composed of resistor R2 and capacitor C2, comes into effect, and the generator is excited. Since the generator input is relatively high-resistance, and resistor R2 connected in series with capacitor C2 has a high resistance, a current pulse of considerable duration will follow. It, in turn, will be filled with a “pause” of shorter pulses, the frequency of which lies within the audio range. These oscillations occur due to the presence of a parallel LC circuit consisting of the inductance of the winding of the capsule BF1, its own capacitance and the capacitance of the capacitor C3, connected by alternating current parallel to winding BF1. Due to the nonlinearity of the charge-discharge process of capacitors C2 and C3, sound vibrations will be additionally modulated in frequency and amplitude. As a result, a sound is formed, reproduced by the BF1 phone as a whistle, which continuously changes timbre, and then breaks off - followed by a pause.

After the discharge of capacitor C2, a new cycle of its charge begins - generation resumes. With each subsequent sound, as the voltage on capacitor C1 decreases, the melody of the whistle becomes different, increasingly interspersed with a clicking sound characteristic of birdsong, and the volume gradually decreases. At the end of the “trill,” several quiet, gentle, fading whistles are heard. After which the voltage at the base of VT1 will drop below its opening threshold (about 0.6-0.7 V), both galvanically connected transistors close, and the sound stops.

After some time, capacitor C1 will be completely discharged (through its own internal resistance, resistor R1, transistor VT1 and emitter junction VT2), the circuit formed by elements R1, C1, VT1 is connected between the base and emitter of transistor VT2, further blocking it and thereby ensuring high efficiency of the device in standby mode. The operation of the simulator is resumed by pressing the button again.

The device can use transistors of the KT201, KT301, KT306, KT312, KT315, KT316, KT342 (VT1) series; KT203, KT208, KT351, KT352, KT361 (VT2) with a static current transfer coefficient of at least 30. Any small-sized resistor R1, for example MLT-0.125, tuning resistor - SPO-0.4, SP3-9a. Capacitors C2, C3 - MBM (KLS, K10-7V), C1-oxide, for example K50-6. Phone BF1 - capsule DEMSH-1, miniature “earphone” TM-2A (the plastic attachment is removed in it - the sound guide) or another, but always electromagnetic, with a winding resistance of up to 200 Ohms; button KM1-1 or MP3.

Adjustment comes down to selecting the position of the trimmer resistor slider, which produces the desired sound effect.

The nature of “singing” can be easily changed by empirically selecting the following elements: C1 within 20-100 µF (determines the total duration of the sound), C2 within 0.1-1 µF (duration of each individual sound). In addition, C2 and R1 (within 470 kOhm - 2.2 MOhm) determine the duration of pauses between the first and subsequent sounds. The timbre coloring of sounds depends on the capacitance of capacitor C3 (1000 pF-0.1 µF).

Modeler-Constructor No. 8, 1989, p. 28

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 sea surf, the crackling of a fire on a hiking trip. Often, some of these sounds need to be reproduced artificially - imitated, simply out of desire, or based on the needs of your technical modeling club, or when staging a play in a drama club. Let's look at descriptions of several sound simulators.

Let's start with the simplest design, this is a simple siren sound simulator. There are single-tone sirens, which produce a sound of one tone, intermittent ones, when the sound gradually increases or decreases, and then is interrupted or becomes single-tone, and two-tone ones, in which the tone of the sound periodically changes abruptly.

A generator is assembled using transistors VT1 and VT2 using an asymmetrical multivibrator circuit. 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 parts necessary to build a multivibrator using transistors of the same structure.

Oscillator oscillations, and hence the sound in the dynamic head, appear due to positive feedback between the collector of transistor VT2 and the base of VT1 through capacitor C2. The tonality of the sound depends on the capacitance of this capacitor.

When switch SA1 supplies supply voltage to the generator, there will be no sound in the head yet, since there is no bias voltage based on transistor VT1. The multivibrator is in standby mode.

As soon as the SB1 button is pressed, capacitor C1 begins to charge (through resistor R1). The bias voltage at the base of transistor VT1 begins to increase, and at a certain value the transistor opens. The sound of the desired tonality is heard in the dynamic head. But the bias voltage increases, and the tone of the sound changes smoothly 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 resistor R1.

As soon as you release the button, the capacitor will begin to discharge through resistors R2, R3 and the emitter junction of transistor VT1. The tone of the sound changes smoothly, and at a certain bias voltage based on transistor VT1, the sound disappears. The multivibrator returns to standby mode. The duration of discharge of the capacitor depends on its capacitance, the resistance of resistors R2, R3 and the emitter junction of the transistor. It is selected in such a way 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 appropriate structure with a static current transfer coefficient of at least 50 can be used in the simulator. In extreme cases, germanium transistors- instead of VT1, MP37A, MP101 can work, and instead of VT2 - MP42A, MP42B with the highest possible static transmission coefficient. Capacitor C1 - K50-6, C2 - MBM, resistors - MLT-0.25 or MLT-0.125. Dynamic head - power 0.G...1 W with a voice coil with a resistance of 6...10 Ohms (for example, head 0.25GD-19, 0.5GD-37, 1GD-39). The power source is a Krona battery or two 3336 batteries connected in series. The power switch and button are of any design.

In standby mode, the simulator consumes a small current - it depends mainly on the reverse collector current of the transistors. Therefore, the switch contacts 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 close, the current consumption increases to approximately 40 mA.

Looking at the circuit of this simulator, it is easy to notice an already familiar unit - a generator assembled on transistors VT3 and VT4. The previous simulator was assembled using this scheme. Only in this case the multivibrator does not operate in standby mode, but in normal mode. To do this, a 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 transistors VT1 and VT2 a symmetrical multivibrator is made, thanks to which a second tone of sound is obtained.

It happens like this. During operation of the multivibrator, the voltage at the collector of 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 - approximately 2 s (i.e., the multivibrator pulse repetition rate is 0.5 Hz). Depending on the state of transistor VT2, resistor R5 bypasses either resistor R6 (through resistor R4 connected in series with resistor R5) or R7 (through the collector-emitter section of transistor VT2). The bias voltage at the base of transistor VT3 changes abruptly, so a sound of one or another tone 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. The capacitors are connected in back-to-back series because the polarity of the signal between the collectors of transistors VT1 and VT2 periodically changes. A conventional oxide capacitor under such conditions performs worse than a so-called non-polar one, for which the polarity of the voltage at the terminals does not matter. When two polar oxide capacitors are connected in this way, an analogue of a non-polar capacitor is formed. True, the total capacitance of the capacitor becomes half that of each of them (of course, with their capacitance being the same).

This simulator can use the same types of parts as the previous one, including the power supply. To supply the supply voltage it is suitable as regular switch with position fixation, and push-button, if the simulator will work as an apartment bell.

Some parts are mounted on printed circuit board(Fig. 29) from one-sided foil fiberglass. Installation can also be mounted in the usual way- using mounting racks for soldering parts leads. 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 housing or mounted near the front door (if there is already a bell button there, its terminals are connected by insulated conductors to the corresponding circuits of the simulator).

As a rule, a simulator installed without errors starts working immediately. But if necessary, it is easy to adjust to obtain a more pleasant sound. Thus, the tonality of the sound can be slightly lowered by increasing the capacitance of capacitor C5 or increased by decreasing it. The range of tone changes depends on the resistance of resistor R5. The duration of the sound of a particular key can be changed by selecting capacitors C1 or C4.

This can be said about the next sound simulator if you listen to its sound. Indeed, the sounds produced by the dynamic head resemble the exhausts characteristic 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 circuit, the engine operation simulator is somewhat reminiscent of a single-tone siren. But the dynamic head is connected to the collector circuit of transistor VT2 through the output transformer T1, and the bias and feedback voltages are supplied to the base of transistor VT1 through variable resistor R1. For direct current it is connected by a variable resistor, and for feedback formed by a capacitor - by a voltage divider (potentiometer). When the resistor slider is moved, 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 rotation speed of the “engine” shaft, and therefore the frequency of sound exhaust.

Transistors KT306, KT312, KT315 (VT1) and KT208, KT209, KT361 (VT2) with any letter indices are suitable for the simulator. 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 the rated voltage not below 6 V. The output transformer and dynamic head are from any small-sized (“pocket”) transistor receiver. One half is used as winding I primary winding. 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 works unstably or there is no sound at all, swap the leads of capacitor C1 with the positive lead to the collector of transistor VT2. By selecting this capacitor you can set the desired limits for changing the speed of the “engine”.

Drip... drip... drip... - sounds come from the street when it rains or in the spring drops of melting snow fall from the roof. These sounds have a calming effect on many people, and according to some, they even help them fall asleep. Well, perhaps you will need such a simulator for the soundtrack in your school drama club. The construction of the simulator will take only a dozen parts.

A symmetrical multivibrator is made on transistors, the loads of which are the high-impedance dynamic heads BA1 and BA2 - “drop” sounds are heard from them. The most pleasant “drop” rhythm is set with variable resistor R2.

To reliably “start” a multivibrator at a relatively low supply voltage, it is advisable to use transistors (they can be of the MP39 - MP42 series) with the highest possible static current transfer coefficient. Dynamic heads should have a power of 0.1 - 1 W with a voice coil with a resistance of 50 - 100 Ohms (for example, 0.1GD-9). If such a head is not available, you can use DEM-4m capsules or similar ones that have the specified resistance. Higher impedance capsules (for example, from TON-1 headphones) will not provide the required sound volume. The remaining parts can be of any type. Power source - 3336 battery.

The simulator parts can be placed in any box and dynamic heads (or capsules), a variable resistor and a power switch can be mounted on its front wall.

When checking and adjusting the simulator, you can change its sound by selecting constant resistors and capacitors within a wide range. If in this case you need a significant increase in the resistances of resistors R1 and R3, it is advisable to install a variable resistor with a high resistance - 2.2; 3.3; 4.7 kOhm to provide a relatively wide range of droplet frequency control.

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 a siren, the proposed multivibrator does not have pulse repetition frequency control circuits. How does the simulator work? Just press (briefly) the SB1 button - and capacitor C1 will charge to the voltage of the power source. After releasing the button, the capacitor will become the source that powers the multivibrator. While the voltage on it is high, the volume of the “blows” of the “ball” reproduced by the dynamic head BA1 is significant, and the pauses are relatively long.

Gradually, as capacitor C1 discharges, the nature of the sound will change - the volume of the “beats” will begin to decrease, and the pauses will decrease. Finally, a characteristic metallic rattling sound will be heard, after which the sound will stop (when the voltage on capacitor C1 drops below the opening threshold of the transistors).

Transistor VT1 can be any of the MP21, MP25, MP26 series, and VT2 can be any of the KT301, KT312, KT315 series. Capacitor C1 - K.50-6, C2 - MBM. The dynamic head is 1GD-4, but another one with good diffuser mobility and a possibly larger area will do. The power source is two batteries 3336 or six cells 343, 373 connected in series.

The parts can be mounted inside the simulator body by soldering their leads to the pins of the button and the dynamic head. Batteries or cells are attached to the bottom or walls of the case with a metal bracket.

When setting up the simulator, the most characteristic sound is achieved. To do this, select capacitor C1 (it determines the total duration of the sound) within 100...200 µF or C2 (the duration of pauses between “beats” depends on it) within 0.1...0.5 µF. Sometimes, for the same purposes, it is useful to select transistor VT1 - after all, the operation 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 if you increase the volume of its sound. The easiest way to do this is to add two capacitors to the device - SZ and C4 (Fig. 33). The first of them directly increases the sound volume, and the second gets rid of the tone drop effect that sometimes appears. True, with such modifications the “metallic” sound 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 significantly higher than in the original simulator.

By connecting a small set-top box to the amplifier of a radio, tape recorder or TV, you can get sounds reminiscent of the sound of the sea surf.

The diagram of such a simulator attachment is shown in Fig. 35. It consists of several nodes, but the main one is the noise generator. It is based on a silicon zener diode VD1. The fact is that when a constant voltage exceeding the stabilization voltage is applied to the zener diode through a ballast resistor with a high resistance, the zener diode begins to “break through” - its resistance drops sharply. But thanks to the insignificant current flowing through the zener diode, such a “breakdown” does not cause any harm to it. At the same time, the zener diode seems to go into noise generation mode, the so-called “shot effect” of its pn junction appears, and at the zener diode terminals one can observe (of course, using a sensitive oscilloscope) a chaotic signal consisting of random oscillations, the frequencies of which lie in a wide range.

This is the mode in which the zener diode of the set-top box 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.

Of course, the amplitude of the noise signal is too small to feed it directly to the radio amplifier. Therefore, the signal is amplified by a cascade on transistor VT1, and from its load (resistor R2) goes to an emitter follower made on transistor VT2, which eliminates the influence of subsequent cascades of the set-top box on the operation of the noise generator.

From the emitter follower load (resistor R3), the signal is supplied to a cascade with a variable gain, assembled on transistor VT3. Such a cascade is needed so that it is possible to change the amplitude of the noise signal supplied to the amplifier, and thereby simulate the increase or decrease in the volume of the “surf”.

To carry out this task, transistor VT4 is included in the emitter circuit of transistor VT3, the base of which receives a signal from a control voltage generator - a symmetrical multivibrator on transistors VT5, VT6 - through resistor R7 and integrating circuit R8C5. In this case, the resistance of the collector-emitter section of transistor VT4 periodically changes, which causes a corresponding change in the gain of the cascade on transistor VT3. As a result, the noise signal at the cascade output (at resistor R6) will periodically rise and fall. This signal is supplied through the capacitor SZ to connector XS1, which is connected during operation of the set-top box to the input of the amplifier used.

The pulse duration and repetition frequency of the multivibrator can be changed by resistors R10 and R11. Together with resistor R8 and capacitor C4, they determine the duration of the rise and fall of the control voltage supplied to the base of transistor VT4.

All transistors can be the same, KT315 series with the highest possible current transfer coefficient. Resistors - MLT-0.25 (MLT-0.125 is also possible); capacitors Cl, C2 - K50-3; NW, S5 - S7 - K.50-6; C4 - MBM. Other types of capacitors 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 material. Place the board in a case of suitable dimensions. Connector XS1 and clamps XT1, XT2 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, there is no need to set up the console. It starts working immediately after power is applied. It is easy to check the operation of the set-top box using high-impedance headphones TON-1, TON-2 or other similar ones, plugged into the sockets of the XS1 “Output” connector.

The nature of the sound of the “surf” is changed (if necessary) by selecting the supply voltage, resistors R4, R6, as well as bypassing the sockets of the XS1 connector 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 contains an audio amplifier and a power supply, so this simulator can be considered a complete design.

The noise generator itself is assembled on transistor VT1 according to the so-called super-regenerator circuit. It is not very easy to understand the operation of a superregenerator, so we will not consider it. Just understand that this is a generator in which oscillations are excited due to positive feedback between the output and input of the cascade. In this case, this connection is carried out through the capacitive divider C5C4. In addition, the super-regenerator is not excited constantly, but in flashes, and the moment of occurrence of the flashes is random. As a result, a signal appears at the output of the generator, which is heard as noise. This signal is often called “white noise”.

The DC operating mode of the superregenerator is set by resistors Rl, R2, R4. Inductor L1 and capacitor C6 do not affect the operating mode of the cascade, but protect the power circuits from the penetration of noise signals into them.

The L2C7 circuit determines the frequency band of “white noise” and allows you to obtain the largest amplitude of the allocated “noise” oscillations. Next, they pass through the low-pass filter R5C10 and capacitor C9 to the amplifier stage assembled on transistor VT2. The supply voltage to this stage is supplied not directly from source GB1, but through a cascade assembled on transistor VT3. 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 transistor VT4 is closed, VT3 opens, and capacitor C12 is charged from source GB1 through the collector-emitter section of transistor VT3 and trimming resistor R9. This capacitor is a kind of battery that powers the amplifier stage. As soon as transistor VT4 opens, VT3 closes, capacitor C12 is discharged through trimming resistor R11 and the collector-emitter circuit of transistor VT2.

As a result, at the collector of transistor VT2 there will be a noise signal modulated in amplitude, i.e., periodically increasing and decreasing. The duration of the rise depends on the capacitance of capacitor C12 and the resistance of resistor R9, and the decline - on the capacitance of the specified capacitor and the resistance of resistor R11.

Through the capacitor SP, the modulated noise signal is supplied to an audio amplifier made 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 supplied to the first stage of the amplifier, assembled on a VT6 transistor. This is a voltage amplifier. From the cascade load (resistor R18), the signal is supplied through capacitor C16 to the output stage - a power amplifier made using transistors VT7, VT8. The collector circuit of transistor VT8 includes a load - dynamic head BA1. From it you can hear the sound of “sea surf”. Capacitor C17 weakens the high-frequency, “whistle” components of the signal, which somewhat softens the sound timbre.

About the details of the simulator. Instead of the KT315V transistor (VT1), you can use other transistors of the KT315 series or the GT311 transistor with any letter index. The remaining transistors can be any of the MP39 - MP42 series, but with the highest possible current transfer coefficient. To obtain greater output power, it is advisable to use the VT8 transistor of the MP25, MP26 series.

Throttle L1 can be ready-made, type 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 on it turn to turn 15...20 turns of PEV-1 0.2...0.4 wire. It is advisable to measure the resulting inductance of the inductor on a standard device and, if necessary, select it within the required limits by decreasing or increasing the number of turns.

Coil L2 is wound on a frame with a diameter of 4 and a length of 12 ... 15 mm from any insulating material using PEV-1 wire 6.3 - 24 turns with a tap from the middle.

Fixed resistors- MLT-0.25 or MLT-0.125, adjustable - SPZ-16, variable - SPZ-Zv (it has a litany switch SA1). Oxide capacitors - K50-6; C17 - MBM; the rest are KM, K10-7 or other small-sized ones. Dynamic head - power 0.1 - I W with the highest possible voice coil resistance (so that the VT8 transistor does not overheat). The power source is two 3336 batteries connected in series, but the best results in terms of operating time will be obtained with six 373 cells connected in the same way. A suitable option, of course, is power supply from a low-power rectifier with a constant voltage of 6...9 V.

The simulator parts are mounted on a board (Fig. 38) made of foil material 1...2 mm thick. The board is installed in a case, on the front wall of which a dynamic head is mounted, and a power source is placed inside. The dimensions of the case largely depend on the dimensions of the power source. 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 be sharply reduced, and the simulator can be mounted in the case of a small-sized transistor radio.

The simulator is set up like this. Disconnect resistor R8 from capacitor C12 and connect it to the negative power wire. Having set the maximum sound volume, select resistor R1 until characteristic noise (“white noise”) is obtained in the dynamic head. Then restore the connection between resistor R8 and capacitor C12 and listen to the sound in the dynamic head. By moving the slider of the tuning resistor R14, the most reliable and pleasant-to-hear frequency of the “sea waves” is selected. Next, by moving the slider of resistor R9, the duration of the rise of the “wave” is set, and by moving the slider of resistor R11, the duration of its decline is determined.

To get a high volume of “sea surf”, you need to connect the extreme terminals of the variable resistor R17 to the input powerful amplifier sound frequency. A better experience can be achieved by using a stereo amplifier with external acoustic systems operating in monophonic signal playback mode.

If you want to listen to the beneficial effects of the measured noise of rain, forest or sea surf. Such sounds relax and calm.

The rain noise generator is made on a TL062 chip, which includes two operational amplifiers. Then the generated sound is amplified by transistor VT2 and sent to the speaker SP. For greater compliance, the HF audio spectrum is cut off by capacitance C8, which is controlled by field-effect transistor VT1, which essentially works as a variable resistance. Thus, we obtain automatic control of the imitator's tone.

The CD4060 counter has a timer with three shutdown time delays: 15, 30 and 60 minutes. Transistor VT3 is used as a generator power switch. By changing the values ​​of resistance R16 or capacitance C10, we obtain different time intervals in the operation of the timer. By changing the value of resistor R9 from 47k to 150k, you can change the speaker volume.

Below are simple light and sound circuits, mainly assembled on the basis of multivibrators, for beginner radio amateurs. All circuits use the simplest element base, no complex setup is required, and it is possible to replace elements with similar ones within a wide range.

Electronic duck

A toy duck can be equipped with a simple “quack” simulator circuit using two transistors. The circuit is a classic multivibrator with two transistors, one arm of which includes an acoustic capsule, and the load of the other is two LEDs that can be inserted into the eyes of the toy. Both of these loads work alternately - either a sound is heard, or the LEDs flash - the eyes of a duck. A reed switch sensor can be used as the SA1 power switch (can be taken from the SMK-1, SMK-3, etc. sensors, used in security alarm systems as door opening sensors). When a magnet is brought to the reed switch, its contacts close and the circuit begins to work. This can happen when the toy is tilted towards a hidden magnet or a kind of “magic wand” with a magnet is presented.

Transistors in the circuit can be any pnp type, low or medium power, for example MP39 - MP42 (old type), KT 209, KT502, KT814, with a gain of more than 50. Transistors can also be used n-p-n structures, for example KT315, KT 342, KT503, but then you need to change the polarity of the power supply, turn on the LEDs and the polar capacitor C1. As an acoustic emitter BF1, you can use a TM-2 type capsule or a small-sized speaker. Setting up the circuit comes down to selecting resistor R1 to obtain the characteristic quack sound.

The sound of a metal ball bouncing

The circuit quite accurately imitates such a sound; as capacitor C1 discharges, the volume of the “beats” decreases, and the pauses between them decrease. At the end, a characteristic metallic rattle will be heard, after which the sound will stop.

Transistors can be replaced with similar ones as in the previous circuit.
The total duration of the sound depends on capacity C1, and C2 determines the duration of pauses between “beats”. Sometimes, for a more believable sound, it is useful to select transistor VT1, since the operation of the simulator depends on its initial collector current and gain (h21e).

Engine sound simulator

They can, for example, voice a radio-controlled or other model of a mobile device.

Options for replacing transistors and speakers - as in previous schemes. Transformer T1 is the output from any small-sized radio receiver (a speaker is also connected through it in the receivers).

There are many schemes for simulating the sounds of birdsong, animal voices, steam locomotive whistles, etc. The circuit proposed below is assembled on just one digital chip K176LA7 (K561 LA7, 564LA7) and allows you to simulate many different sounds depending on the value of the resistance connected to the input contacts X1.

It should be noted that the microcircuit here operates “without power,” that is, no voltage is supplied to its positive terminal (pin 14). Although in fact the microcircuit is still powered, this happens only when a resistance sensor is connected to the X1 contacts. Each of the eight inputs of the microcircuit is connected to the internal power bus through diodes that protect against static electricity or incorrect connection. The microcircuit is powered through these internal diodes due to the presence of positive power feedback through the input resistor-sensor.

The circuit consists of two multivibrators. The first (on elements DD1.1, DD1.2) immediately begins to generate rectangular pulses with a frequency of 1 ... 3 Hz, and the second (DD1.3, DD1.4) comes into operation when the logical level " 1". It produces tone pulses with a frequency of 200 ... 2000 Hz. From the output of the second multivibrator, pulses are supplied to the power amplifier (transistor VT1) and a modulated sound is heard from the dynamic head.

If you now connect a variable resistor with a resistance of up to 100 kOhm to the input jacks X1, then power feedback occurs and this transforms the monotonous intermittent sound. By moving the slider of this resistor and changing the resistance, you can achieve a sound reminiscent of the trill of a nightingale, the chirping of a sparrow, the quack of a duck, the croaking of a frog, etc.

Details
The transistor can be replaced with KT3107L, KT361G, but in this case you need to install R4 with a resistance of 3.3 kOhm, otherwise the sound volume will decrease. Capacitors and resistors - any type with ratings close to those indicated in the diagram. It must be borne in mind that the K176 series microcircuits of early releases do not have the above protective diodes and such copies will not work in this circuit! It’s easy to check the presence of internal diodes - just measure the resistance with a tester between pin 14 of the microcircuit (“+” power supply) and its input pins (or at least one of the inputs). As with diode testing, the resistance should be low in one direction and high in the other.

There is no need to use a power switch in this circuit, since in idle mode the device consumes a current of less than 1 µA, which is significantly less than even the self-discharge current of any battery!

Setup
A correctly assembled simulator does not require any adjustment. To change the tone of the sound, you can select capacitor C2 from 300 to 3000 pF and resistors R2, R3 from 50 to 470 kOhm.

Flashing light

The flashing frequency of the lamp can be adjusted by selecting elements R1, R2, C1. The lamp can be from a flashlight or a car 12 V. Depending on this, you need to select the supply voltage of the circuit (from 6 to 12 V) and the power of the switching transistor VT3.

Transistors VT1, VT2 - any low-power corresponding structures (KT312, KT315, KT342, KT 503 (n-p-n) and KT361, KT645, KT502 (p-n-p), and VT3 - medium or high power (KT814, KT816, KT818).

A simple device for listening to the sound of TV broadcasts on headphones. Does not require any power and allows you to move freely within the room.

Coil L1 is a “loop” of 5...6 turns of PEV (PEL)-0.3...0.5 mm wire, laid around the perimeter of the room. It is connected in parallel to the TV speaker via switch SA1 as shown in the figure. For normal operation of the device output power The TV audio channel should be within 2...4 W, and the loop resistance should be 4...8 Ohms. The wire can be laid under the baseboard or in the cable channel, and it should be located, if possible, no closer than 50 cm from the wires of the 220 V network to reduce alternating voltage interference.

The L2 coil is wound onto a frame made of thick cardboard or plastic in the form of a ring with a diameter of 15...18 cm, which serves as a headband. It contains 500...800 turns of PEV (PEL) wire 0.1...0.15 mm secured with glue or electrical tape. A miniature volume control R and an earphone (high-impedance, for example TON-2) are connected in series to the coil terminals.

Automatic light switch

This one differs from many circuits of similar machines in its extreme simplicity and reliability, and in detailed description does not need. It allows you to turn on the lighting or any electrical appliance for a specified short time, and then automatically turns it off.

To turn on the load, just briefly press switch SA1 without latching. In this case, the capacitor manages to charge and opens the transistor, which controls the relay switching on. The turn-on time is determined by the capacitance of capacitor C and with the nominal value indicated in the diagram (4700 mF) it is about 4 minutes. An increase in the on-state time is achieved by connecting additional capacitors in parallel with C.

The transistor can be any n-p-n type of medium power or even low-power, such as KT315. This depends on the operating current of the relay used, which can also be any other with an operating voltage of 6-12 V and capable of switching the load of the power you need. You can also use p-n-p type transistors, but you will need to change the polarity of the supply voltage and turn on capacitor C. Resistor R also affects the response time within small limits and can be rated 15 ... 47 kOhm depending on the type of transistor.

List of radioelements

If all parts are in good working order and installed without errors, the simulator does not require any adjustment. Nevertheless, remember the following recommendations. The frequency of repetition of trills can be changed by selecting resistor R5. Resistor R7, connected in series with the head, affects not only the sound volume, but also the frequency of the blocking oscillator. This resistor can be selected experimentally, temporarily replacing it with a variable wire resistor with a resistance of 2...3 Ohms. When achieving the highest sound volume, do not forget that distortion may appear, deteriorating the sound quality.

Rice. 48. Simulator circuit board
When repeating this simulator, in order to obtain the desired sound, it was necessary to slightly change the values ​​of the parts and even rebuild the circuit. Here, for example, are the changes made to one of the designs. The chain C4, C5, R6 is replaced by a capacitor (oxide or other type) with a capacity of 2 μF, and instead of resistor R5, a chain of a series-connected constant resistor with a resistance of 33 kOhm and a trimmer resistance of 100 kOhm is included. Instead of the chain R2, C2, a capacitor with a capacity of 30 μF is included. Resistor R4 remained connected to the terminal of inductor L1, and between the terminal and the base of transistor VT2 (and therefore the positive terminal of capacitor C1) a resistor with a resistance of 1 kOhm was connected, and at the same time a resistor with a resistance of 100 kOhm was connected between the base and emitter of transistor VT2. In this case, the resistance of resistor R2 is reduced to 75 kOhm, and the capacitance of capacitor C1 is increased to 100 μF.

Such changes can be caused by the use of specific transistors, a transformer and inductor, a dynamic head, and other parts. Listing them makes it possible to experiment more widely with this simulator to obtain the desired sound.

In any case, the functionality of the simulator is maintained when the supply voltage changes from 6 to 9 V.
^ TRILLS OF THE NIGHTINGALE
Using part of the previous design, you can assemble a new simulator (Fig. 49) - the trill of a nightingale. It contains only one transistor, on which a blocking oscillator with two positive feedback circuits is made. One of them, consisting of inductor L1 and capacitor C2, determines the tonality of the sound, and the second, composed of resistors Rl, R2 and capacitor C1, determines the trill repetition period. Resistors Rl - R3 determine the operating mode of the transistor.

^ Rice. 49. Circuit of a nightingale trill simulator on one transistor
The output transformer, inductor and dynamic head are the same as in the previous design, the transistor is of the MP39 - MP42 series with the highest possible current transfer coefficient. Power source - any (from galvanic batteries or rectifier) ​​with a voltage of 9... 12 V. Resistors - MLT-0.25, oxide capacitors - K50-6, capacitor SZ - MBM or another.

There are few parts in the simulator and you can arrange them yourself on a board made of insulating material. The relative position of the parts does not matter. Installation can be either printed or mounted, using racks for parts leads.

The sound of a simple simulator largely depends on the parameters of the transistor used. Therefore, setting up comes down to selecting parts to obtain the desired effect.

The tone of the sound is set by selecting the capacitor SZ (its capacity can be in the range from 4.7 to 33 µF), and the desired duration of the trills is by selecting resistor R1 (ranging from 47 to 100 kOhm) and capacitor C1 (from 0.022 to 0.047 µF). The plausibility of the sound largely depends on the operating mode of the transistor, which is set by selecting resistor R3 in the range from 3.3 to 10 kOhm. The setup will be greatly simplified if, instead of constant resistors R1 and R3, variables are temporarily installed with a resistance of 100 - 220 kOhm (R1) and 10 - 15 kOhm (R3).

If you want to use the simulator as an apartment bell or sound alarm, replace the SZ capacitor with another, larger capacity (up to 2000 µF). Then, even with a short-term supply of power to the bell button, the capacitor will instantly charge and act as a battery, allowing you to maintain a sufficient duration of sound.

A diagram of a more complex simulator, which requires virtually no setup, is shown in Fig. 50. It consists of three symmetrical multivibrators that produce oscillations of different frequencies. Let's say the first multivibrator, made on transistors VT1 and VT2, operates at a frequency of less than a hertz, the second multivibrator (it is made on transistors VT3, VT4) - at a frequency of several hertz, and the third (on transistors VT5, VT6) - at a frequency of more than a kilohertz. Since the third multivibrator is connected to the second, and the second to the first, the oscillations of the third multivibrator will be bursts of signals of different durations and slightly varying frequencies. These “bursts” are amplified by a cascade on the transistor VT7 and are fed through the output transformer T1 to the dynamic head BA1 - it converts the “bursts” of the electrical signal into the sounds of a nightingale trill.

Note that to obtain the required simulation, an integrating circuit R5C3 is installed between the first and second multivibrators, which allows “converting” the pulse voltage of the multivibrator into a smoothly rising and falling one, and between the second and third multivibrators a differentiating circuit C6R10 is connected, providing a shorter duration control voltage compared to with a prominent resistor R9.

The simulator can operate transistors of the MP39 - MP42 series with the highest possible current transfer coefficient. Fixed resistors - MLT-0.25, oxide capacitors - K50-6, other capacitors - MBM or other small-sized ones. Transformer - output from any transistor receiver with push-pull amplifier power. Half of the primary winding of the transformer is connected to the collector circuit of the transistor. Dynamic head - any low-power one, for example 0.1GD-6, 0.25GD-19. Power source - 3336 battery, switch - any design.

Rice. 50. Circuit of a nightingale trill simulator using six transistors
Some of the simulator parts are placed on a board (Fig. 51), which is then installed in a housing made of any material and suitable dimensions. A power source is placed inside the case, and a dynamic head is mounted on the front wall. You can also place a power switch here (when using the simulator as an apartment bell, instead of a switch, connect the bell button located at the front door with wires).

^ Rice. 51. Simulator circuit board
Testing the simulator begins with the third multivibrator. Temporarily connect the upper terminals of the resistors R12, R13 to the negative power wire. A continuous sound of a certain tone should be heard in the dynamic head. If you need to change the tone, just select capacitors C7, C8 or resistors R12, R13.

Then restore the previous connection of resistors R12, R13 and connect the upper terminals of resistors R7, R8 to the negative wire. The sound should become intermittent, but not yet similar to the singing of a nightingale.

If this is the case, remove the jumper between resistors R7, R8 and the negative wire. Now a sound similar to a nightingale trill should appear. A more accurate sound of the simulator can be achieved by selecting parts of the frequency-setting circuits of the first two multivibrators - base resistors and feedback capacitors.
^ FOR DIFFERENT VOICES
Some rearrangement of the circuit of the electronic “canary” - and now a circuit appears (Fig. 52) of another simulator, capable of producing the sounds of a wide variety of feathered inhabitants of the forest. Moreover, adjusting the simulator to a particular sound is relatively simple - just move the handle of one or two switches to the appropriate position.

As in the electronic “canary”, both transistors operate in a multivibrator, and VT2 is also part of the blocking oscillator. The frequency-setting circuits of the simulator include sets of capacitors of different capacities, which can be connected using switches: using switch SA1, the tonality of the sound is changed, and using SA2, the repetition frequency of trills is changed.

In addition to those indicated in the diagram, other low-power germanium transistors can operate with the highest possible transmission coefficient (but not less than 30). Oxide capacitors - K50-6, the rest - MBM, KLS or other small ones. All resistors are MLT-0.25 (you can use MLT-0.125). The choke, output transformer and dynamic head are the same as in the “canary”. Switches - any design. Suitable, for example, are 11P2N biscuit switches (11 positions, 2 directions - it is made up of two boards with contacts connected by one axis). Although such a switch has 11 positions, it is not difficult to bring them to the required six by moving the limiter (it is located on the switch handle under the nut) into the corresponding hole in the base.

Rice. 52. Scheme of a universal trill simulator

Rice. 53. Simulator circuit board
Some parts are mounted on a printed circuit board (Fig. 53). The transformer and inductor are attached to the board with metal clamps or glued. The board is installed in a housing, on the front wall of which switches and a power switch are fixed. The dynamic head can also be placed on this wall, but good results are obtained by mounting it on one of the side walls. In any case, a hole is cut out opposite the Diffuser and covered from the inside of the body with a loose fabric (preferably radio fabric), and from the outside with a decorative overlay. The power source is secured at the bottom of the Housing with a metal clamp.

The simulator should start working immediately after turning on the power (if, of course, the parts are in good condition and the installation is not messed up). It happens that due to the low transmission coefficient of the transistors, the sound does not appear at all or the simulator operates unstable. The best way in this case, increase the supply voltage by connecting another 3336 battery in series with the existing one.
^ HOW DOES A CRICK CLICK?
The cricket chirping simulator (Fig. 54) consists of a multivibrator and an RC oscillator. The multivibrator is assembled using transistors VT1 and VT2. Negative pulses of the multivibrator (when transistor VT2 closes) are supplied through diode VD1 to capacitor C4, which is the “battery” of the bias voltage for the generator transistor.

The generator, as you can see, is assembled on just one transistor and produces oscillations of a sinusoidal sound frequency. This is a tone generator. Oscillations arise due to the action of positive feedback between the collector and the base of the transistor due to the inclusion between them of a phase-shifting chain of capacitors C5 - C7 and resistors R7 - R9. This chain is also frequency-setting - the frequency generated by the generator, and therefore the tone of the sound reproduced by the dynamic head BA1, depends on the ratings of its parts - it is connected to the collector circuit of the transistor through the output transformer T1.

During the open state of transistor VT2 of the multivibrator, capacitor C4 is discharged, and there is practically no bias voltage at the base of transistor VT3. The generator does not work, there is no sound from the dynamic head.

Rice. 54. Cricket sound simulator circuit

Rice. 55. Simulator circuit board
When transistor VT2 closes, capacitor C4 begins to charge through resistor R4 and diode VD1. At a certain voltage at the terminals of this capacitor, transistor VT3 opens so much that the generator begins to work, and a sound appears in the dynamic head, the frequency and volume of which changes as the voltage across the capacitor increases.

As soon as transistor VT2 opens again, capacitor C4 begins to discharge (through resistors R5, R6, R9 and the emitter junction circuit of transistor VT3), the sound volume drops, and then the sound disappears.

The repetition frequency of the trills depends on the frequency of the multivibrator. The simulator is powered from source GB1, the voltage of which can be 8...I V. To isolate the multivibrator from the generator, a filter R5C1 is installed between them, and to protect the power source from generator signals, capacitor C9 is connected in parallel with the source. When using the simulator for a long time, it must be powered from a rectifier.

Transistors VT1, VT2 can be of the MP39 - MP42 series, and VT3 - MP25, MP26 with any letter index, but with a transmission coefficient of at least 50. Oxide capacitors - K50-6, the rest - MBM, BMT or other small-sized ones. Fixed resistors - MLT-0.25, trimmer R7 - SPZ-16. Diode - any low-power silicon. The output transformer is from any small-sized transistor receiver (half of the primary winding is used), the dynamic head is 0.1 - 1 W with a voice coil with a resistance of 6 - 10 Ohms. The power source is two 3336 batteries connected in series or six 373 cells.

The simulator parts (except for the dynamic head, switch and power supply) are mounted on a printed circuit board (Fig. 55). It can then be mounted in a case, inside which the power supply is located, and on the front panel - the dynamic head and power switch.

Before turning on the simulator, set the trimmer resistor R7 to the lowest position according to the diagram. Apply power to switch SA1 and listen to the sound of the simulator. Make it more similar to the chirping of a cricket with trimming resistor R7.

If there is no sound after turning on the power, check the operation of each node separately. First, disconnect the left terminal of resistor R6 from parts VD1, C4 and connect it to the negative power wire. A single-tone sound should be heard in the dynamic head. If it is not there, check the installation of the generator and its parts (primarily the transistor). To check the operation of the multivibrator, it is enough to connect high-impedance headphones (TON-1, TON-2) in parallel with resistor R4 or the terminals of transistor VT2 (through a capacitor with a capacity of 0.1 μF). When the multivibrator is working, clicks will be heard in the phones, following after 1...2 s. If they are not there, look for an installation error or a faulty part.

Having achieved the operation of the generator and multivibrator separately, restore the connection of resistor R6 with diode VD1 and capacitor C4 and make sure that the simulator is working.
^ WHO SAID "MEOW"!
This sound came from a small box, inside of which was an electronic simulator. Its circuit (Fig. 56) is a bit reminiscent of the previous simulator, not counting the amplification part - an analog integrated circuit is used here.

^ Rice. 56. Scheme of the “meow” sound simulator
An asymmetrical multivibrator is assembled using transistors VT1 and VT2. It produces rectangular pulses, following at a relatively low frequency - 0.3 Hz. These pulses are supplied to the integrating circuit R5C3, as a result of which a signal with a smoothly rising and gradually falling envelope is formed at the terminals of the capacitor. So, when the transistor VT2 of the multivibrator closes, the capacitor begins to charge through resistors R4 and R5, and when the transistor opens, the capacitor is discharged through resistor R5 and the collector-emitter section of transistor VT2.

From the capacitor SZ, the signal goes to the generator, made on transistor VT3. While the capacitor is discharged, the generator does not work. As soon as a positive pulse appears and the capacitor is charged to a certain voltage, the generator “triggers” and an audio frequency signal (approximately 800 Hz) appears at its load (resistor R9). As the voltage across the capacitor SZ increases, and therefore the bias voltage at the base of the transistor VT3, the amplitude of oscillations at the resistor R9 increases. At the end of the pulse, as the capacitor discharges, the amplitude of the signal drops, and soon the generator stops working. This is repeated with each pulse removed from the load resistor R4 of the multivibrator arm.

The signal from resistor R9 goes through capacitor C7 to variable resistor R10 - the volume control, and from its engine to the audio power amplifier. The use of a ready-made amplifier in an integrated design made it possible to significantly reduce the size of the design, simplify its setup and ensure sufficient sound volume - after all, the amplifier develops a power of about 0.5 W at the specified load (BA1 dynamic head). “Meow” sounds are heard from the dynamic head.

Transistors can be any from the KT315 series, but with a transmission coefficient of at least 50. Instead of the K174UN4B microcircuit (former designation K1US744B), you can use K174UN4A, and the output power will increase slightly. Oxide capacitors - K53-1A (C1, C2, C7, C9); K52-1 (NW, S8, S10); K50-6 is also suitable for a rated voltage of at least 10 V; the remaining capacitors (C4 - C6) are KM-6 or other small ones. Fixed resistors - MLT-0.25 (or MLT-0.125), variable - SPZ-19a or another similar one.

Dynamic head - power 0.5 - 1 W with voice coil resistance 4 - 10 Ohms. But it should be taken into account that the lower the resistance of the voice coil, the greater the amplifier power that can be obtained from the dynamic head. The power source is two 3336 batteries or six 343 cells connected in series. Power switch - any Design.