Simple Miniature FM Transmitter 

it works very well and it is very simple to build, even for amateurs.

 When using small wire antenna and 3V power the range is 50m.

The coil has 10 turns on a 3 mm diameter and is wound with 0.3 mm copper wire (29 AWG).

The microphone is an electret type.

Transmitting frequency is changed by stretching or compressing the coil.

Furthermore, we can change the frequency by changing C2 capacitor (10pF capacitor with a frequency of about 88MHz, with 8.2pF 95Mhz and 6.8pF 104Mhz).

Further tuning to the correct frequency is done through the coil. Transmitter can be powered by 3V button battery.  

500mW FM / VHF Transmitter Amplifier / Booster

High performance low noise 500mW amplifier / booster for all low power FM transmitters such as BA1404, BH1417, BH1415, 433MHz transmitter modules, etc.

The amplifier chip is an integrated circuit containing multiple transistor stages and all other parts conveniently within a single small package.

Boosting your FM transmitter has never been easier and the output signal can also directly drive 2n4427 or 2n3866 transistors for 1W or 5W of RF output power.  

Gollum's Crystal Receiver