Radio microphone - radio chip

This is perhaps the most popular simple and common radio or radio microphone scheme. A minimum of detail and a minimum of time is required to build this baby. Thanks to the use of a microphone from Chinese products, the sensitivity of this device is very high. This scout is not whimsical to manufacture, not picky about the power source. Of course, along with the obvious advantages of this scheme, there are drawbacks, the main one, in my opinion, is the large frequency drift when the power is changed, but when powering this radio microphone from batteries this parameter is not critical.
This radio works according to the capacitive three-ton scheme. The oscillatory circuit is tuned to 90 MHz. But with ease you can choose any frequency from the interval of 30 - 120 MHz.  
TransistorKT660B.Thecoilis7mmindiameter,therestisinthephoto.
Thetransistorcanbeany,evenlow-frequency.&Nbsp;
Withgoodparts,thebugstartsworkingimmediately.Youonlyneedtoselectthedesiredfrequency.
Definingtheworkofabugwithoutareceiverisverysimple.Todothis,measurethecurrentconsumption,andthenshorttheoscillatingcircuit,ifthecurrentconsumptionhaschanged,thedeviceisworking.
Theantennaisconnectedtothecollectorofthetransistor,itcanbeapieceofwireuptoameterlong.Itisbettertoconnecttheantennathroughacapacitorof10-15pF.
Iforgottodraw,thepowerisconnectedtothecapacitorC1theupperterminalisapluscircuit.Food1.5   - 15 volts.


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