A small FM transmitter (SMD)
This SMD FM transmitter has an operating frequency of about 80 to 115MHz. Under reasonable circumstances you will be able to receive its signal at a distance of about 200 meters. Although it is low-power, it might be illegal in your part of the planet. Circuit diagram:
 Depending on the electret microphone you use, you might have to tweek R4 to set the gain of the pre-amplifier. Depending on the Q of the LC-part (usually not very good when using off-the-shelf SMD parts) you may also have to re-bias the end stage of the circuit. For the coil you can use a ECM45T Series Inductor . 
You can download the PCB design here (only 2.5Kb). It's a double-sided PCB in CorelDraw 3.0 format (zip compressed).
author: Oscar den Uijl
e-mail: odu@xs4all.nl
web site: http://www.xs4all.nl/~odu/
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