K3NG Keyer complete

I finally build K3NG’s Arduino CW Keyer and put it in a nice box. Here’s how it looks:

K3NG Arduino keyer, complete

That’s a SparkFun Arduino Project Enclosure with two buttons (one command, one macro), a CW speed control potentiometer, and a simple 3.5mm audio jack for keying the transmitter.

Enclosure base, showing piezo and potentiometer

I’ve glued a cheapo piezo (UHU All Purpose glue is my piezo glue of choice; cyanoacrylate is too brittle) onto the base, and cut a hole in the side for the speed pot. The piezo gives a clear enough side tone that I can copy CW (or Hellschreiber, as before) with audio output into Fldigi. The beeper’s got a fierce third harmonic, but that’s part of its charm. K3NG has a more complex speaker circuit, but this is simple and self-contained.

Enclosure lid, with buttons and resistors

Two momentary switches ($2 from Active Surplus) make up the control interface.

Arduino+Protoboard, and the magic of a 2N2222 switch

The clever bit is an Arduino Duemilanove Uno (my oldest board; it deserves a proper useful home which doesn’t seem to have the serial startup problems my Duemilanove had) with an Adafruit Proto Shield on top. The only “clever” componentry on that is a solitary 2N2222 switching transistor.

It works pretty well. The only thing that doesn’t seem to be stable is the memory button; it seems to choose randomly from any of the first four memories, so I might accidentally send an SK when I meant a CQ. For now, until I work out what’s wrong, I’ll stick to keyboard input of the macros.

K3NG Arduino Keyer

I’m pretty amazed that the above image is even vaguely readable. It’s Hellschreiber, generated by Anthony K3NG Good’s Arduino CW Keyer. What you’re seeing, though, is Hellschreiber from the keyer’s sidetone generator being fed through a piezo glued to a paper cup (and not just any paper cup) being picked up by Fldigi on my laptop’s microphone. This isn’t what you’d call a quality signal path, and it’s a tribute to the mode’s robustness that it can be made out at all.

Anthony has packed an absurd amount into this keyer. There isn’t enough memory on a stock 32K Arduino for all the features to be enabled. I’m planning to use it as a CW keyer alongside Fldigi as the decoder. Despite all the features that can be built in, I’d just be using it as a serial to Morse converter, with perhaps a couple of memory keys for calling CQ and the like.

I do have a slight problem with it while it’s breadboarded, though. The wiring’s so sensitive that the control circuit triggers if I put my hand near it, let alone touch the command button. I’ll have to do something about that. I can’t breadboard for toffee.