SIMPLE AUDIO TRANSMITTER

Send

This transmitter showed good quality of the transmitted music, so I recommend starting with this scheme.
As practice has shown, an assembled generator on one transistor cannot, stand in one place, without an additional cascade, the frequency constantly goes out when a hand is brought up or applies voltage. I used the transmitter within the same room, so I did not, they will use an additional cascade. As you can see, two transistors are used in this generator, which allows you to leave the frequency stable. Varikap excluded from the scheme, in my opinion, did not play a significant role.

Supply voltage 6 volts. Consumption current 0.2 amperes. The range is 88-107 MHz.
The frequency goes down when it supplies voltages up to 3.7 volts, therefore I recommend that you include a voltage regulator for 5 volts "7805" in the circuit, such stabilizers are on the FM transmitters, on the board from the DVD. The diode set to increase the voltage.

The LED also helps keep the generator more stable. This generator does not respond to foreign objects or when raising a hand, unless of course we hold onto the antenna. A transformer for a voltage of 9 v, ampere 0.2 is used in the power supply. Diodes IN4007, you can of course IN4004, IN4001. 3300 uF electrolyte. And be sure to shunt each diode with a 10n capacitor, otherwise it will be nasty to flash.
Between the case and the plus, you also need to hook the 10n capacitor.

The length of the antenna is about 35 cm, the distance to a mobile phone with obstacles is 60 m. Still, you do not need to connect a spiral antenna, worsens the efficiency, range, wideband and if you plug it into a wall socket, then the background from alternating voltage will appear. Those who used such antennas were deeply mistaken. GOOD LUCK TO ALL RADIO FANS AND LOVERS.