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A PICAXE-14M2 BASED ELECTRONIC KEYER (Ver.2)

 

Yep, yet another keyer circuit! This one uses the PICAXE-14M2 chip and is programmed in "BASIC". Beware I am not a programmer by profession or as a hobbyist! But the code seems to work OK.  There are three CW modes and a practice mode available. Iambic Mode "A", Iambic Mode B, Bug Mode and a random Morse Code generator for practice in groups of five. Prior to downloading the code, you can make a simple change to the .BAS file and choose letters, numbers or a few punctuation symbols for the practice groups. When the keyer is powered up, you have 2 seconds to either press and hold the Dit paddle for Iambic Mode"A", the Dah paddle for Bug Mode, both the Dit and Dah paddles for the random Morse Code generator or do nothing for 2 seconds and go to Iambic Mode "B". Of course, this can be changed in the code before you download it into the PICAXE chip. Feel free to change anything. Optimize the code, add a new feature if you like. There is heaps of code space left!  The output relay is a bit ""clicky & clanky"". In other words, it sounds like a telegraph keyer somewhat!  I'm not sure if a commercial keyer makes any relay noise, I've never owned one.  Possibly I should of used a reed relay or something of that sort? At some point I may alter the art work to include that type of relay. One downfall of this project, you have to cycle power to change modes. 

 

**** PLEASE READ ****

If you decided to build this keyer, then you've probably etched out a circuit board before. The circuit board artwork was painfully made with MS Paint. Although it was slow going, it was pretty fun. PLEASE NOTE..... it's the required "mirror" image but it's not to scale. The keyer artwork needs to be printed out so the outside dimensions of the artwork are 80mm x 80mm for what ever technique you use to do the transfer to copper.  

 

I personally import the artwork image into Word for Windoz, rescale it to 80mm x 80mm and then copy and paste it 5 more times to the .doc file. I do a test print of the six 80mm x 80mm images to a single piece of A4 paper. Then the scaling is checked again by setting the IC socket, relay and LM7805 onto the A4 paper and over what would be the holes in the copper pads. If the IC socket pins line up to the copper pad holes, all is OK, the scaling is correct. Now your ready for the transfer. I use the special blue plastic transfer sheets sold by Jaycar Electronics and print it out using a laser printer. The blue plastic sheet people say you can use a photo copier to print the image, but I have not tried the copier. Either way, printing to the blue plastic sheet MUST use toner, not ink. I am told that the toner has microscopic pieces of plastic in it and this is what transfers (melts?) from the special blue plastic sheet to the very well prepared bright, shiny and very very clean circuit board copper. I use the wifies iron with a heat setting on "silk" and iron about  four to five minutes to transfer the mirror image from the blue plastic sheet to the copper. I let it cool for a half an hour or more, then slowly peel the plastic off the copper leaving only the black toner on the copper. Some touch up may be required with a printed circuit board pen. Then into the hot ammonium persulphate solution for about 10 minutes of etching. Then the dreaded .7mm and 1mm hole drilling. Then the best part, soldering all the parts on and downloading the code into the PICAXE. 

 

 Just a note, I did read somewhere on the internet that you can laser print to the old overhead projector transparent plastic sheets rather then Jaycar's expensive special blue plastic sheets. I've not tried that yet, but it would save you a few dollars as the special blue plastic sheets are a bit expensive in my opinion. My wifie says that thin clear plastic sheets sold for "scrapbooking" at K-Mart might work too. But again, I haven't tried that yet either.   * Enjoy *

 

The Circuit Board Art Work     The Schematic     The Etched Board     Bill of Materials

 

A Mixture of Code

 

Mode A Code     Mode A Code w/Sound     Mode A Code w/Auto-Spacing     Mode A Code w/Auto-Spacing and Sound

 

Mode B Code     Mode B Code w/Auto-Spacing 

 

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