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MORSE OSCILLATOR.  
Everyone will tell you, the Morse code can not be learned with the eyes,  
but with the ears.  
I propose to you, a small oscillator BF (Low Frequency),  
for the learning of the manipulation and the initiation to the listening ... to be even.  
Much more pleasant to listen to than a simple vibrator and closer to the CW programs  
that you can listen to because this montage generates an adjustable tone,  
restored by a small speaker.  
Easy to use, it is autonomous and can be powered from 5 to 16 volts DC.  
A 9 volt battery will do the trick.  
 
Principle:  
This oscillator is made around an integrated circuit NE 555,  
that we are going to wire as an oscillator of square signals.  
It is he who will charge directly into the speaker,  
for which we will choose an impedance of hundreds of ohms.  
A manipulator, interposed on the + of the power supply, will act as a switch.  
Depending on our ear, we will adjust the tone of the BF  
by retouching the adjustable potentiometer.  
You can replace the latter by an adjustable potentiometer with a button.  
 
The realization:  
This assembly presents no particular difficulty,  
except the presence of 4 polarized components,  
(2 diodes and 2 capacitors) whose polarity must not be reversed and NE 555,  
that it will of course be necessary to implement in a good way.  
To avoid any risk of deterioration, it will not weld directly on the plate,  
but it will be plugged into a small base.