This is a morse code practice oscillator that I built when I was studying to take the code exam. What I found out was that I could send code great, but was going to be tested on receiving, not sending. Any way this project was one of my first construction projects and got me going with building. I hope that maybe it will get someone else building also.
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As you can probably see all the parts for this project were bought from Radio Shack. With the exception of the the key. It is an Ameco key bought from AES. This is my main key that I still use. I'm not really a big morse code fan, but I think I am getting better. I am working on an adapter for using morse code on a 2 meter HT. Hopefully, with the intent of becoming better at it and also helping others to get going with the code. |
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The device consists of a containing box, a 8 ohm 4 inch speaker, the oscillator circuit, and various input output connectors. It was sometime ago that I built this and I am unable to find my parts list for it. Most of it you can infer from the pictures. |
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This really shows the guts of the thing. All components are mounted on the back side of the front panel. On the left you can see the actual oscillator circuit. This is the back of the oscillator circuit, the actual component side is face down. Underneath the the circuit board, all the I/O connectors and switches are mounted through the front panel. As you can see the the circuit board is mounted on standoffs, which hold it above the connectors and switches. On the right side, is the system speaker. Note the conveinent battery holder the speakers magnet makes. |
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This image shows better the mounting of the components. Mainly how the circuit board is mounted over the switches and I/O connectors. |
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This is a schematic of the circuit that I used. It is a 555 timer IC set up as an astable multivibrator. This circuit produces a pulsating DC output at a frequency governed by the relationship of R1, R2, and C1. R1 and R2 are the actual values I used in the circuit. Then I played around with C1 to tailor the tone to one I liked. Basically start C1 around 11nF, then add or subtract capacitance to get the tone you want. Have fun with it! |