When learning Morse code (referred to as CW in ham radio circles) a practice oscillator can be helpful. It lets you practice your sending without transmitting. Also, if can be useful if you are wanting to practice sending/receiving CW with another ham through a Skype channel without waiting for propagation conditions. A voice channel like Skype also allows immediate voice feedback for effective Elmering.
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We shelled out $10US on eBay and a few days later we got the practice oscillator pictured above in kit form from Electroresales with some good instructions. After about 30 minutes we had a working (and very loud if you crank the volume) practice oscillator. We made one small mod by adding a JST connector in parallel to the power barrel jack. This made it easier (for us anyway) to connect a 9VDC battery without having to find the right size barrel jack connector to supply the power.
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The result:
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