FM Transmitter
A portable FM transmitter that can be used to replace a FM microphone. 
Notes:
This simple transmitter operates from a 9V battery as shown above. I personally built this for a purpose. This is how it happened:-"members of my singing group find it difficult to handle a FM mic in Church. The choir sings in acapella form and the congregaTIon expect us to perform well. The old FM mic system was not a perfect soluTIon, so I built this kit and a mixer for the receivers. using three separate transmitter circuits and a mixer on the receiever, the choir voices were perfect and cleanly reproduced. "
From the notes I made experimentally, C3 is vital to the circuit and without it the circuit may become unstable. C4 is in parallel with C5 and presents a moderate load impedance. Finally all transistors are NPN. The circuit works well and has proved reliable.
L1 Details:
In the circuit L1 has 6 turns and has a diameter of 5.5mm and has a length of 4.5mm. Based on the formula for an air cored inductor: 
Using the above values, the inductance of L1 can be calculated. A diameter of 5.5mm = 0.22 inches, the radius is half this value or 0.11 inch, the length is 4.5mm and number of turns, n = 6. This gives L1 a value of: 
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