• Yesterday I built this 1 transistor transmitter. It works, but when i put my hand near the base wire(10 cm from it), for parasitic capacitance the transmitter instead of transmitting audio signal, acts as a repeater (I am the antenna) and transmits over the tuned radio frequency the audio signal coming from the strongest radio station.
• parasitic capacitance is so high because the base wire is long 10 centimeters and I don't use printed circuit board.
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  HOW CAN I SOLVE THE PROBLEM???

this is my version

 

If is possible without using pcb

 

Hello,

You could use the manhattan style prototyping as descibed in the links of this post:
http://forum.allaboutcircuits.com/t...ps-and-tricks-thread.12878/page-2#post-152539

Bertus

 

ok thank you
but do you think the problem is solved?

 

Hello,

The long wires you are using to connect the parts can act as an antenna and change the frequency of the circuit.
Building the circuit on a steady base short wires will make it more stable in use.

Bertus

 

thank you. I will build it

 

This must be your first oscillator.

Some tuning might help, but your problem is physical, not electrical,,,, yet. Your circuit is occupying to much area, or volume you might call it. Your circuit is too big.

This is the "art" part of electronics. This art is based on a different kind of beauty.

We can show you how to stabilize your circuit.

But you must read and study to see and understand the beauty of it.

 

It's not my first oscillator

i built a hartley and a colpitts but this is my first oscillator that can transmit in the fm band (the others only in the CW band)

Thank you for the advices. where can I study about the beauty of circuits you have talked?

 

"Electronic Communication", Robert L. Shrader, second edition.
Amazon................about $30.