CPO Complete

Yesterday I completed my Code Practice Oscillator previously described here. All appears to work basically as planned, and best of all the option to hook up the headphones output to my computer works a treat.

Doing that, I can readily record the output with Audacity. This provides two possibilities:

  • Being able to record some code, and then listen to it the following day to see if I can read it. A recommended method to evaluate the quality of your code.
  • I can readily see the timing/spacing of the individual elements of my sent code to ensure they’re the correct duration – ie. that my dits are indeed a third of my dahs.

Also with Audacity I could readily see the square wave that is being produced – and the slight distortion at turn on.
Hopefully I’ll provide some more on the use of Audacity soon. But for now I’ve provided a quick sample that I recorded last night. But please, be nice, I’m still learning to send – a ways to go yet! πŸ™‚

I’ve also provided the schematic for the CPO I came up with. As you can see, it’s pretty simple just based around the NE555 IC to generate a square wave. A couple of specifics though:

  • ‘KEY’ is where them morse key connects via a 3.5mm mono headphone socket – it also acts as the switch (which works better than I expected – no audible impact on tone);
  • R1 is for the tone control;
  • R3 is for volume control;
  • S1 provides manual switching between 3.5mm headphones jack and the built in speaker;
  • SP1 is just a basic 0.5W 8 ohm speaker; and
  • Capacitors with decimal values are in uF – ie. 0.1 specifies a 100nF capacitor.

All this was assembled point to point and dead bug style. Then once confirmed working the NE555 was just hot glued onto the inside of the container – you can actually read the chip number on the outside of the container. πŸ™‚

Hopefully on the week-end I might have time to take some photos or maybe even a video – but we’ll see.

VK1IS – CW.wav


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