I bring to your attention a spy radio microphone with extremely low power consumption. This is perhaps the longest lasting bug I have ever collected.
Of course, you have to pay for the low power consumption with a short range, but for many purposes this is quite enough.
The radio microphone confidently penetrates two reinforced concrete walls, and in open space the range will be from 50 to 200 m (depending on the steepness of your receiver).
The bug's circuit is incredibly simple and contains only 6 radio components, not counting the battery:
Coil L1 - 4 turns with 0.5 mm wire on a Ø2mm mandrel. Choke - 100 nH for surface mounting. Transistor BFR93A (the main thing is not to confuse it with the pnp transistor BFR93).
and etched in ferric chloride: 
All this took about 20 minutes. Then I tinned the finished board and cut off the excess: 
The most difficult thing is to connect the battery. I had at my disposal an old (!!!) CR2032 lithium battery (which is usually found in motherboards to power the BIOS chip).
To avoid unnecessary wires, I simply glued a strip of tin from a tin can to the back of the board (this will be the negative contact): 
The remaining piece of tin was useful as a positive terminal: 
The battery must be tightly inserted into the resulting slot, like this: 
All that remains is to solder all the parts onto the board according to the diagram: 
I'm sure it can be made even smaller. Replace the microphone, place the parts closer together, take small watch batteries and you're done. It will be possible to stuff the entire circuit, for example, into the body of a marker.
I used a 6 cm long wire as an antenna. The choke was made by winding a thin enameled wire on a piece of toothpick (80 turns). 
The microphone, of course, is too big for such a circuit, but I didn’t have anything else. In general, any electret with a diameter of 3-10 mm will do. Usually they are taken out of any telephone or intercom handsets.
By the way, the circuit does not work without a microphone - power goes through it. It also acts as a current stabilizer.
It is important not to confuse the polarity of the microphone: the negative terminal should ring into the body (that is why I put it in heat shrink, so that God forbid, nothing short-circuits). 
The frequency is adjusted by compressing/stretching the coil turns. In my case, the bug was caught at a frequency of 424.175 MHz. The signal level at such a distance, naturally, goes off scale: .jpg)
If you wind 11 turns on a 2 mm mandrel, the frequency will be approximately 150 MHz. In general, this bug works up to 1 GHz. I didn’t try further, because... nothing to catch.
To test the range, I went outside and walked around the house. Amazingly, in the room where the bug remains, every rustle is clearly audible.
P.S. This tiny bug worked on a half-dead battery for almost 2 weeks! It’s scary to imagine how long it would last on a new one, because the current consumption is only 300 µA. 
In order to organize wiretapping, you can resort to several ways to implement your plan. Electronic tracking devices can be purchased at a store or ordered via the Internet. However, a quality one will cost the consumer a pretty penny. As a rule, cheap Chinese devices quickly fail, and they are not particularly distinguished by practicality. One thing remains - to make a bug with your own hands, especially since this is quite feasible, and the cost of components (in order to manufacture this or that audio surveillance device) is essentially symbolic. However, let's get down to business.
Legal grounds
Of course, you need to understand that special means for listening are the prerogative of the special services. In case of violation of the constitutional rights of the individual and proven guilt in an infringement on the secret of private life, administrative punishment will follow. There are cases when it comes to criminal liability. Therefore, do not "abuse" the manufactured product. It is much wiser to use such a device as an additional security measure or use it to exercise acoustic control over the territory of your own home. For example, a homemade bug for wiretapping will be a great “informant” if you are not sure about the decency of the nanny you hired or want to know what is happening in the classroom at school. But you never know life situations when the use of listening devices becomes a necessity.
Mobile "GSM bug": an incredibly simple solution
In order to make an eavesdropping device from a cell phone, you need a device that supports the "Auto-hook" function, you also need a headset (headphones). The device can be considered the most acceptable for such purposes, since the simplicity and reliability of the telephone allow us to count on the success of the project being implemented. By the way, it is a sign of profitability, the energy consumption of the device is significantly reduced. Believe me, such a do-it-yourself phone bug is an excellent substitute for expensive listening equipment. Moreover, literally everyone can do the simple actions described below. Let's get started.
- Go to the phone menu and enter the "Call mode" section.
- Create your personal mode. All items related to light indication, vibration, volume of the signal melody, screensaver, sound accompaniment of button presses and notification of incoming SMS messages must be deactivated.
- Give the new mode a name.
- Through the main menu, find the “Accessory Settings” section, which usually has two sub-items “headset” and “hearing aid”. In each of them, it is necessary to edit the operating parameters and the question of how to make a bug will be practically solved.
- All "accessory" items must be included. Assign the newly created mode as active and exit the settings.
- Cut off the cord from the headphones and insert the plug into the headset jack.
- The display should show the activated mode.
We use the smartphone for other purposes
When leaving on a business trip or vacation, you can leave at home a kind of watchman, so to speak, a mobile “guard”. And you don’t need to solder anything, and the cell bug is a do-it-yourself converted smartphone. Everything else is just primitive.
- Almost all smartphones are equipped with the "Auto-receiving calls" function.
- In relatively new cellular units, the energy-saving mode technology is implemented. Therefore, taking into account the known good condition of the device, you can count on 5-7 days of your battery.
- It is possible that the phone is connected to the charger, and a special device with a time relay acts as an intermediary between the socket and the charger. An hour a day is a completely acceptable power supply mode (considering the situation described above).
- Turn off the sound notification, light indication and vibration mode in your phone.
- It would not be superfluous to take such an action as installing headphones in the headset jack, since the sound background around the caller will be an unfavorable signal that will determine the location of the spy device.
- Place the device in middle zone living space. Do not forget: the device should not be in a conspicuous place, but it is not a solution either. Place the phone on the mezzanine or fix it on the back of a hanging picture.
A bug for wiretapping: do-it-yourself from "improvised means"
Usually not thrown away. Find a long-forgotten "electronic comrade", because it is from him that you will make an efficiently working sound pickup device. It is worth noting that almost any phone can be converted into an eavesdropping device. However, size plays an important role in the "spy life". Therefore, in such a delicate matter as wiretapping, it is more expedient to use small models of phones.
General flow diagram
- Disassemble your phone.
- Remove the screen and remove all LEDs (keyboard backlight - leave one for visual control).
- Solder the power button.
- Install the device - "Auto-accept a call", because the bug with its "hands" must pick up the phone.
- Replace the microphone with a more sensitive (electret) one.
- Build up the antenna (regular copper wire 15-20 cm).
- Solder battery and fix it on top of the keyboard pad (elastic band, adhesive tape).
- You check the functionality.
The optocoupler shown in the diagram can be replaced with a KT315 type transistor or Western counterparts C9018, C9014. In this case, the capacitor is removed, and the resistor is set with a resistance value of 2.2 k.
miniature bug
You can make an FM transmitter with your own hands. Enough simple circuit will allow you to receive a signal in the radio frequency range of 88-92 MHz. You should not immediately run to the store and buy parts, you may have faulty electrical equipment, from the board of which you can dismantle the necessary components.
You will need:
- Bipolar transistor - 2N3904 or its equivalent.
- Resistors - 4.7 and 330 kOhm.
- Capacitors - 4.7 pF, 1 and 22 nF.
- Trimmer capacitor, nominal value 30 pF.
- Loop coil - winding diameter 6 mm, eight-turn, wire 0.5 mm.
- The material for the board is foil fiberglass.
- Battery type "Krona" at 9 watts.
- (the most sensitive is used in tape recorders).
We collect the FM bug for wiretapping
- First of all, a tuning capacitor is soldered (middle of the board). The transistor is mounted on the left.
- Moving to the bottom, we install (from left to right) capacitors: the first is 4.7 pF, the second is 1 nF.
- Now solder the resistors.
- After - a 22 nF capacitor and a frameless coil.
- The construction is completed by a wire - an antenna, installation of a microphone and soldering of the battery.
In conclusion
Now it is not a secret for you how to make a bug out of your phone and what is needed for this. The variants of GSM and radio products presented in this information review are only a part of the many electronic samples available, through which high-quality acoustic control can be established. However, it should be noted that practicality and quality are achieved through the application of the above recommendations. However, perhaps there will be a "craftsman" who will come up with a more rational way to realize the excellent performance of his inventions of the listening type. In the meantime, we will use what we have. Listen carefully!
What was published some time ago, quite serious results were obtained. At 10.5 volts and 24 mA, one hundred meters at idle mobile phone with FM. This is the same distance for a Degen digital receiver, but with a folded telescopic antenna. On the Chinese FM receiver - the Mamba scanner, it takes confidently at 100 meters. The sensitivity of the microphone is very high, but this was not an easy task, I spent two days setting up, setting modes... Although the generator itself started up without any problems, I noticed one thing - the current consumption by the generator also depends on the feedback capacitor. I had to reduce its capacity, with installation it turned out to be 2 pf. Here the capacitance can be seen added by the installation itself, two parallel tracks of 2-3 picofarads were added. The electronic bug's circuit design and parameters turned out to be the same as the author's, with the exception of some values and the method of biasing the amplification stage. Acoustic sensitivity is not bad, about 5-8 meters, which cannot be said up close. In short, I was a little dissatisfied with the sound.
Therefore, experiments were continued, the sensitivity was high, but too much, and I did not add AGC, so as not to complicate the circuit. I just decided to modulate the RF generator differently. The low-frequency amplifier remained standard, only a varicap-capacitor chain was added to the master oscillator. 100% FM modulation is now available.
Now the microphone sensitivity is even very high! The varicap capacity turned out to be much more than enough; with a C6 capacity of 15 pf, a mid-tone conversation in the next room can be easily heard. Acoustic sensitivity was several times higher than that of a similar version, it was decided to reduce the capacitance, so it stopped at 3 pf. I tried with different varicaps, KV109-122 there is not much difference, a weak level - you increase the C6 capacity, a strong level - you decrease it. In this embodiment, the acoustic overload from strong sounds (conversation close to the microphone) turned out to be more acceptable.
The printed circuit board was slightly redesigned, with the same dimensions. The board came out 40x18 mm. I didn’t change the circuit data, and the frequency even roughly matched. I almost did not notice the frequency drift - I freely took it in my hands, any manipulation with the antenna, but of course not in the master circuit. Naturally, if placed in a screen, it will be no worse than quartz. Below are photos of several variants of bugs with varicap modulation:
And here is another option for converting an electronic bug.
The change mainly affected the low-frequency part of the beetle. Large amplifications are not always needed, so it was decided to remove the bass amplifier altogether, and see what happens. But that was not the case! Sensitivity turned out to be enough, the entire room is well audible. Even a certain acoustic test was formed - a quartz electromechanical watch, the audibility is excellent.
Here, do not forget that the sensitivity will directly affect the quality of the microphone itself (it is advisable to try several copies). Output power, microphone sensitivity, transmission frequency - coincided with the first version of the electronic bug.
Naturally, the fee has decreased somewhat, and the microphone acoustic overload is already completely absent: it is very loud near, but there is not even a hint of distortion. From the brand of the varicap and from the capacitance of the capacitor C6, the bug simply turned into a radio microphone. The sensitivity of the microphone dropped significantly, the circuit was freely handled by hand. It turned out pure speech, 30-50 cm. And most importantly, there is no noise - there is silence in the receiver, listening to the room is a pleasure! Experiments were conducted by -igRoman-
On the Internet, you can find a huge number of radio bug schemes. Some circuits are too complex and require tuning, others include scarce radio components, and still others do not work at all!
I bring to your attention a diagram of a bug that can be assembled by both an experienced radio amateur and a beginner in this business.
Let's take a look at this diagram:
Ignore the dotted line for now.
To make a bug, we need the following parts:
- VT1 - kt315 with any letter index (if you want to increase the range of the bug, it is better to use a microwave transistor, for example kt325 or kt368, the imported transistor s9018 is perfect);
- C1, C4 – 47…68nf;
- C2, C3 - 10pf;
- R1 - 33 kOhm;
- R2 - 100 Ohm;
- Oscillatory circuit L1 - 8 turns of copper wire with a diameter of 0.3 ... 0.5 mm on a rod from a helium pen, wind carefully, turn to turn (I soldered the finished coil from a broken radio).
- M1 - electret or condenser microphone.
In order to save space, I used the right microphone (found in an old mobile phone). Despite his size, he proved to be very sensitive.
All parts, except for the L2 choke and microphone, are shown in the following picture:
To make L2, we need a match and a very thin wire:
We measure one and a half centimeters of a match, bite them off - this piece will serve as the core of the throttle. Next, we take the wire and wind a hundred turns. We fix the conclusions of the resulting coil, clean it from varnish, tinker. That's it, the L2 choke is ready!
When all the parts are assembled, you can begin to manufacture the printed circuit board.
To do this, we need a piece of textolite 35x15mm and the solution itself, in which we will etch the board (I used hydrogen peroxide + citric acid). We make a drawing of a printed circuit board (I drew under the s9018 transistor)
and transfer it to textolite.
We put the board in the solution and wait until the excess copper disappears.
After the board is etched, we take it out, rinse it with running water, remove the varnish and tin it:
Next, solder the parts in accordance with the diagram. Attention, when mounting parts on the board, do not overheat them, otherwise they will fail! Be especially careful with the installation of VT1.
I want to say a few words about connecting the antenna, the signal is fed to it from the emitter of the transistor, which makes the operating frequency of the bug more stable.
Assembled circuit:
The bug can be powered in the range from 1.5 to 9 volts.
Any of these batteries will work to power the circuit. I used an AAA battery for a more compact bug. You can also use a 3 volt "tablet".
If you feed the circuit from a crown (9 volts), then you should include a 100 ohm resistor R3 in the circuit.
Carefully solder the battery to the bug. An insulated wire 30 cm long can be used as an antenna, but practice has shown that its absence will not greatly affect the reception range of the circuit. Everything, the bug is ready!
Now we turn on the radio and look for the frequency of our bug. The signal from it can be caught at a frequency in the range of 88-108 MHz. I have this frequency was 92.2 MHz. If the bug "does not get in touch", then try to push the turns of the L1 coil - this should help solve the problem.
With a supply voltage of 1.5 volts, the receiving range is 30 meters, if you increase the voltage to 3 volts, then the receiving range will increase to 100 meters.
This circuit also has another application - an audio transmitter. Let's say you need to output sound from your phone to a tape recorder, but the latter does not have an audio input function. No problem! In this situation, this scheme is very useful. Almost all tape recorders have a radio reception function (FM radio), and we will use it. Remember the dotted line on the bug diagram? We exclude microphone M1 from the circuit, connect capacitor C5 to a capacitance of 10 microfarads, connect a 3.5mm “mini-jack” plug to the negative of the capacitor and the negative of the power supply (minus the “jack” to the common, left / right to the negative of the capacitor) and transmit sound from the phone to any radio receiver within the range of the transmitter! At correct installation details, the circuit starts working immediately.
You can use these products for a variety of purposes: from listening to rooms and to wireless sound transmission.
And this is where my article comes to an end, good luck to everyone in the repetition!
", and can also be assembled after quite complex structures such as "Wasp" or "Bumblebee". In general, the article is designed for beginner "Beetle Makers" who have collected and launched at least the first beetle. So here it is. I want to offer you one of the options for a single transistor beetle with good characteristics, compared to conventional schemes. Of course, the scheme is not original and there is nothing unusual in it. And what to collect this diagram you must at least be able to hold a soldering iron in your hands and distinguish between a resistor and a transistor. that is, have at least a little experience working with a soldering iron. If something is not clear in the diagram, then I strongly recommend that you first collect the "First Beetle", and now read everything that is written in the first message, including links. This will not make things worse, but knowledge will increase.
So let's return to our beetle.
The bug has the following characteristics:
Supply voltage: 0.8-1.7 V* (One(!) 1.5 V battery)
Sensitivity: 7-10M**
Range: 50-400M***
Current consumption: 1.5-2 mA
Operating frequency: VHF(88-108MHz) or 180-200MHz****
Notes:
* The bug is designed to be powered by one battery with a nominal voltage of 1.5V; higher voltage can lead to an uncontrolled increase in current consumption until the transistor fails!
** Sensitivity depends on the microphone used; with a Chinese microphone with a diameter of ~3 mm there are no complaints about the sensitivity; a quiet conversation can be heard well.
*** The range very much depends on the characteristics of the receiving device (receiver) used. On a Chinese two-button scanner it will be about 50M, and on a normal receiver it will be 200M. We managed to get 400M to a receiver based on CXA1691 with a non-standard switching circuit. The frequency was 180 MHz. You won't get that range on the FM band. At the same time, reception on 400M was good, if you don’t take into account that you have to stand in one place, move a little to the left or right and the signal disappears.
**** This article gives two versions of the bug for different frequencies, while the circuit diagram of the device does not differ, only the winding data of the L1 coil changes.
So here it is. Let's get acquainted with the scheme of this beetle. Here she is.
As you can see, the circuit does not contain complex components or non-standard values. All parts can be easily purchased or removed from unnecessary equipment. To increase efficiency, a choke is included in the emitter circuit of the transistor. With this switching on, the output power of the generator increases and there is no low-frequency feedback. Therefore, the sensitivity of the microphone is comparable to two transistor beetles. It is advisable to select a transistor with the highest hFE, although any high-frequency transistor will do. A correctly assembled circuit begins to work immediately after power is applied. Resistor R1 can be used to select the required current consumption and output power. The connection with the antenna is made small, which somewhat reduces the output power, but increases stability. The beetle is made on a double-sided printed circuit board measuring 20x20mm on which all components are placed. SMD 0805 parts. However, conventional lead elements can also be used. If the board is double-sided, then the second side must be connected to the minus, preferably in several places. I installed the transistor S9018, but you can use SMD. The transistor can be replaced with KT368 or BFR93. I removed the choke from the Chinese scanner receiver. I also recommend that you take it from there. It is advisable to take parts such as according to the diagram, for example, it is not advisable to take 15 pF instead of 12 pF, although it is acceptable. Resistors with a deviation of no more than 10-15%. It is better to collect beetles on SMD. There will be better stability. You can, of course, assemble it using DIP, but it is desirable that they be made of good quality, especially the capacitors. Do not use red capacitors under any circumstances. Your bug's frequency will fluctuate greatly as the ambient temperature changes when using these capacitors. If you assemble a beetle like this (at the bottom of the page), then don’t be surprised that the beetle does not work, or works poorly.
The coil is wound on a mandrel with a diameter of 3 mm with a 0.5 mm wire and contains 6 turns for the FM range. Then the coil must be stretched as in the photo.
For the range of 180-200 MHz, the coil should be wound with a 0.5 mm wire on a 3 mm mandrel; the coil will contain 3 turns.
PCB drawing: 
I cut the board with a regular cutter.
Photos of beetles: 
Closer. 
Yes, by the way, when using good batteries, the beetle can work stably for about a month. I tested for about a month. Then I just got tired of waiting and I took it off and measured the voltage on the battery - 1.2V. So he could work for another month. At the same time, microphone sensitivity and range remained the same. And the frequency drift was about 150 kHz.
