Share
Pin
Tweet
Send
Share
Send
This is perhaps the most popular simple and common radio bug or radio microphone circuit. A minimum of detail and a minimum of time is required to build this baby. Due to the use of a microphone from Chinese products, the sensitivity of this device is very high. This bug is not whimsical in manufacturing, not demanding on a power source. Of course, along with the obvious advantages of this circuit, there are drawbacks, the main one, in my opinion, is a large frequency drift when changing the power supply, but when this radio microphone is powered by batteries, this parameter is not critical.
![](http://img.uaft2404.org/img/sdela-2019/radiomikrofon-radiozhuchok.jpg)
This radio beetle works according to the capacitive three-ton scheme. The oscillation circuit is tuned to a frequency of 90 MHz. But with ease you can choose any frequency from the interval 30 - 120 MHz.
![](http://img.uaft2404.org/img/sdela-2019/radiomikrofon-radiozhuchok-2.jpg)
Transistor KT660B. The coil is a frame with a diameter of 7mm, see the rest for the rest.
The transistor can be any, even low-frequency.
With good parts, the bug starts working immediately. It is only required to select the desired frequency.
![](http://img.uaft2404.org/img/sdela-2019/radiomikrofon-radiozhuchok-3.jpg)
It is very simple to determine the operation of a bug without a receiver. To do this, measure the current consumption, and then short-circuit the oscillating circuit, if the current consumption has changed, then the device is working.
The antenna is connected to the collector of the transistor, it can burn to be a piece of wire up to a meter long. It is better to connect the antenna through a 10-15 pF capacitor.
I forgot to draw, the power is connected to the capacitor C1, the top pin is in the plus circuit. Power supply 1.5 - 15 volts.
Share
Pin
Tweet
Send
Share
Send