Morse Code Practice Oscillator

This is a Morse code practice oscillator I built.  The first homebrew project I ever built was a code buzzer like this, but unfortunately I no longer have it.  I found plans for a similar project in the August 2003 issue of WorldRadio in an article entitled "Simple Code Key For The Beginner" by Howie Krausse W5OM.  Howie constructed a CW oscillator into an Altoids box with a straight key mounted on the lid.   I constructed mine in the same way. The circuit is a simple oscillator circuit based on a 555 timer IC.  There are only a few components needed to construct it.  Parts list: IC1- 555 timer R1 - 150k R2 - 1K C1 - 10 uF electrolytic C2 - .01 uF ceramic disc Speaker 9V battery clip

Lowering the value of R1 will lower the pitch of the tone.  A 150K potentiometer can be substituted to adjust the pitch.  I used three 300K resistors in parallel.  I used two because I didn't have a 150K resistor on hand, and used the third one to lower the pitch even further from what it originally was.  The oscillator puts out a square wave, so it will sound better and less raspy with higher pitches than lower ones.  A pot is the best way to find a comfortable pitch.  I cut the key out of a piece of PC board and mounted it to the lid with a couple of screws & nuts.  I added a couple more layers of PC board to provide a gap between the key lever and the contact screw, which was insulated from the lid by means of a plastic washer.  A rubber cabinet foot attached to the key lever acts as a knob.  The board & speaker were attached to the inside of the tin by double-sided foam tape.  The Altoids box was given a coating of dark blue metallic paint.

The simplicity of this project makes it perfect for the new ham just getting into homebrewing.  It will also act as a handy tool to practice CW skills.

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