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This miniature transmitter is easy to construct and it’s transmissions can be picked up on any standard FM radio. It has a range of up to 1/4-mile (400 meters) or more, depending on the line-of-sight, obstructions by large buildings, etc. It is great for room monitoring, baby listening, nature research, etc.
L1 is 8 to 10 turns of 22 gauge hookup wire close wound around a non-conductive 1/4-inch diamter form, such as a pencil.
C4 is a small, screw-adjustable, trimmer capacitor. Read the rest of this Electronic Schematic entry here»

Here is another mini circuit project. This is a Mini Amplifier that have a simple tone control. Here is the Scheamatics

Mini Amplifier

You can comment here if get something wrong with this electronic schematic design

Here is a small project about FM receiver that you can built with a little cost. The schematic below

This is a very simple kind of receiver. The dificult point is to get the inductor coil, i think there a no electronic store that sell this coil. so you must make it by yourself

Below i have finished develop a mini fm transmitter that work fine at frequency 88 – 108 MHz. This is a simple FM Transmitter that can be used in a small city (2-4 Km). Here is the schematics

mini fm transmitter

if you could not understand please feel free to comment here