Surveillance Spy Bug Transmitter
Powerful - Stable - Small

Main Features

  • 1.5  miles  (2.4 Km)  range  minimum
  • Sensitive  microphone  with  limiter
  • PLL tuning for exact frequency control
  • Transmits in broadcast quality stereo
  • Can be used to transmit music to a radio
  • Small size a little over a square inch
  • Easy to build with supplied  PC Board
  • Uses readily available SMD components

Spy Bug FM Transmitter - Ultra Small

Spy bugs, FM bugs, long range FM transmitter, miniature transmitters, call them whatever you like but we are sure that you won't find anything like this one anywhere else because we designed it to be better than any other FM bug transmitter that we have seen and you can build it yourself if you have some basic skills.

Click here if you think you might like to build one and see how to get a kit.The transmitter you see here is so small that it can be used as a surveillance bug but it works more like a professional quality FM wireless microphone. It even transmits broadcast quality stereo sound and its range will surprise you. That's why it's called the LONG RANGER™.
This is not a toy.

Read about the range tests. Click here. You will be amazed how far it can transmit.



This transmitter is powerful, stable, sensitive and small.You can use it for covert surveillance or as a baby monitor, this includes your teenagers.
Find out what they get up to when you are not around. the microphone is so sensitive that you could hear a pin drop on the floor.

It can also be wired to plug into your MP3 Player, iPhone, iPod or Android device and transmit  broadcast quality stereo music to an FM receiver. Plug it into an electric guitar, who needs a guitar amplifier?
Use it in your car to listen to the music on your smart phone via your car stereo.
Plug it into your laptop's sound output and listen to the sound on your FM stereo.
Set up a low powered FM Radio station on your campus or neighborhood.

It's not difficult to make an FM transmitter that does all this but the hard part is making it fit into a square inch.
Which is exactly what we have done. It could have been made smaller but because it's a DIY kit we wanted it to still be easy to assemble.

Phase Locked Loop (PLL) Digital Tuning

This device transmits on the FM broadcast band so it can be received on any FM radio.
Today's modern receivers all use digital tuning so it made sense to design our bug to do the same.

Most so called spy bugs, use simple oscillators with a coil and capacitor tank circuit as a frequency determining element. Their frequency is not stable enough. Despite the fact that many of those so called spy shops claim that they sell their products to authorities all over the world, it's hard to believe that such devices can be used for anything more than just learning about electronics.

More useful and professional listening devices derive their carrier frequency from a quartz crystal. Crystals are ideally suited for creating a very precise and stable frequency generator.
This transmitter uses a crystal with a phase locked loop (PLL) and transmits exactly on the frequency desired accurate to one decimal place. (Eg. 107.5Mhz)

Click here to find out how a PLL works.

As the receiver will be tuned exactly to the stable transmit frequency, it will be received further away. The transmitter and receiver will be perfectly matched.
No guessing what frequency the FM transmitter will be on because it will be exactly where you tuned it. No frequency drift due to temperature, battery voltage change or stray capacitace effects.

Compare that to the cheap FM bugs that use a coil and capacitor for tuning and drift even as you are trying to adjust the frequency due to stray capacitance from your hand.
No more screw driver tuning here with this unit, instead you select the exact frequency with wire links.

There is another reason why it's desirable to use a PLL.
If a transmitter were to use just a crystal oscillator it would only be able to transmit on the frequency of the crystal (Or multiples of that frequency). Also on the FM broadcast band where these FM bugs are used the deviation of the transmitter needs to be 75KHz wide as this is the way receivers are designed, wide band FM as it's called.
This is how the nice high fidelity sound is achieved.

Unfortunately it's difficult to get a quartz crystal to move that far so such an FM transmitter would be limited to transmitting narrow band FM as is used on most two way radios.
One drawback with NBFM is that it sounds a bit tinny as it's missing a lot of the audio frequencies.

A Phase Locked Loop circuit gives you all the advantages, stability of a quartz crystal, flexibility of frequency output channels, wide or narrow deviation or any type of modulation required for that matter and with the many different chips available for this purpose you usually get all the other functions built into the chip.
In our case here with the chip we used you get FM stereo, microphone limiting and broadcast quality audio processing in a tiny chip.

Spy Bug Size - Extremely long Range

This bug is powered by 5 to 6 volts DC so it can be used with a couple of 3v coin cells or AA batteries.
It can also be powered from a USB port.
The output power can be varied according to your needs for range and battery life.
Power can be varied from 20mW up to over 100mW
This is done simply by the choice of one component in the output amplifier.
This transmitter is unlike anything else available on the internet, it performs more like a miniature broadcast radio station and has high quality stereo sound with pre-emphasis but it's very small and can easily be hidden.

Wireless Microphone Audio Processing

The microphone amplifier has a built in limiter circuit that attenuates loud sounds such as yelling directly into the microphone but also allows full gain when faint sounds are present. Just like the human ear it adjusts automatically to suit the sounds in the room.
This means that distortion of any sound is kept to a minimum whether it's people talking or a whisper in another room.

Electronic Kit

Available as an electronic kit. Learn about electronics and radio transmitters by building it yourself. Practice your skills at soldering surface mount (SMD) components.

This Build it yourself kit is unlike any other FM bug transmitter available, we designed it to be a high performer, with great range, stability, microphone sensitivity and it's very easy to tune.
To make such a transmitter requires over 50 components but the board has been designed to fit all the components in an area just a little larger than a square inch.

It is an ideal way to learn about surface mount soldering methods and the end result is a freakishly cool and useful device. Even people who are not interested in electronics will want one once they hear it working.

Click here to find out more about this unique electronic kit.

Comes complete with a coprehensive assembly manual that is written in the style of a magazine constructional project. There is a detailed explanation of how the transmitter works and modifications you can make.
The manual is written by a native english speaking engineer so it is easy to understand. 

For a limited time you can buy this FM bug transmitter kit including shipping.

To order this amazing kit at the introductory price of $59.95 please click here .

Warning! Please check the laws in your country before operating this transmitter.
This device is for educational purposes only and the responsibility for operating it remain totally with the person operating it. We are not responsible for what you do with it.



Here is a short Video on the transmitter

© 2024 Radio Spy Bug | Website by eDIY