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A PICAXE-14M2 BASED ELECTRONIC KEYER (Ver.3)

 

YEP, ANOTHER KEYER

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 four CW eletronic keyer modes, a keyer practice mode with output only to the speaker and seven CW practice modes. 

 

Available Iambic keyer Modes are, Iambic Mode A, Iambic Mode A w/auto spacing, Iambic mode B and Iambic Mode B w/auto spacing. The keyer practice mode only sends an output "Tone" to the speaker. The CW practice modes are random Morse Code generators for practice in groups of five. The traditional stuff like, Letters, Numbers or Punctuation. Or a combination of all of them. Basically the technique of using the 1 pole 12 position switch with twelve 1K resistors in series enable you to have 12 menus, so to speak. This is heaps better then the previous Version 2 model which only had 4.

 

Of course, 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!  You might want to remove the "link" and silence the relay if you are only using the MOSFET to key your rig.  Next project I will alter the art work to use a reed relay that is very quiet.

 

**** PLEASE READ ****

If you decided to build this keyer, then you've probably etched out a circuit board before. The circuit board art work 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 art work needs to be printed out so the outside dimensions of the art work are 80mm x 80mm for what ever technique you use to do the transfer to copper.

 

TRANSFER THE IMAGE TO PHOTO PAPER

I personally import the art work .BMP 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 in the holes that would be the copper pads, then all is OK. The scaling is correct.

 

Now your ready for the transfer. I personally DO NOT use the special BLUE plastic "Press and Peel" transfer sheets sold by Jaycar Electronics anymore.  What I have found as the key to 100 percent art work transfer in the backyard circuit board process.... "DO NOT PEEL". I personally use standard high gloss A4 computer photo paper and transfer the correctly "scaled and mirrored" image file to the high gloss paper with a good quality laser printer. It must be a laser printer and NOT an inkjet printer. I am told that the laser toner has microscopic pieces of plastic in it and this is what melts and transfers the toner from the photo paper to the very well prepared bright, shiny and very very clean circuit board copper.

 

CLEAN CLEAN CLEAN THE COPPER!

 I personally use 400 grit wet and dry sand paper under water in the laundry sink and sand the dirty, tarnished and oxidized copper until it is bright and shinny. I then dry it off with a paper towel. Sometimes I even wipe the copper down with alcohol just to make sure there is nothing left on the copper.

 

TRANSFER THE IMAGE TO COPPER

Next, I pre-heat my cheap $20 dollar laminator for about 20 to 30 minutes. While this is happening, I set the prepared copper board on top of the laminator to pre-heat the copper. Next, I set the glossy photo paper with image facing down onto the shiny copper and run it through the hot laminator about 10 - 12 times. I try not to send the copper through the laminator in the same spot. I always move it to another position on the laminator rollers. My theory is, the rollers will be hotter since the rollers did not transfer heat to the photo paper and copper circuit board on the previous pass. Beware, the image may not stick to the copper the first pass through the hot laminator, so when it comes out the back of the laminator, do not let the paper move before sending it through for the second time. The image should be obviously sticking by the second or third pass or the laminator is not hot enough.

 

I now let the board cool for a half hour or more. Then I ever so carefully separate the smooth backing off the glossy photo paper. Do not let the image pull up from the copper. I have found that removing this smooth backing material off the glossy photo and exposing the coarse or rough paper in between the smooth backing and high gloss front of the photo paper sure helps as stated below.

 

Next I heat up a kettle of water to about 80 degrees C. Place the copper board in the laundry sink and pour the hot water in, but not directly on the paper and copper. The smooth backing material having been removed from the glossy photo paper helps lets the hot water get into the gloss photo paper and "water logs" it and releases the toner image from the high gloss side of the photo paper. The glossy photo paper should lift and float away from the copper after 10 minutes or so and will leave all of the toner image on the copper. NO PEELING! If you don't or can't remove the smooth backing, it can take hours for the photo paper to lift and float away. One time it took 2 days for a large complex image to float away!!! So, it's up to you.

 

ETCHING

I use Ammonium Persulphate for etching. Etching takes about 10-15 minutes to remove all the unprotected copper. One of the key points here is to keep the solution above 75 degrees C. I do this by boiling up a full kettle of seriously hot water.  I use use two old plastic Ice Cream tubs with the top tub having about 5mm of very hot water and the appropriate amount of Ammonium Persulphate. The bottom tub is filled to about 3/4, or about 50mm high. The top tub basically floats on top of a reservoir of hot water to keep the top 5mm of solution from dropping below 75C for as log as possible.

 

DRILLING THO HOLES

I use a cheap $99 dollar drill press and .8 mm, 1.0 mm and a 1.2 mm drill bits to drill the appropriate holes. To deburr the holes on the top side of the board, I twisting a 3mm bit with my fingers into each hole. This knocks off all the burrs.

 

AND LAST...

The best part, soldering all the parts on and downloading the code into the PICAXE microcontroller chip.

 

 

The BASIC Code        The Circuit Board Art Work        The Schematic        The Bill of Materials

 

 

Version 3 - Top View

 

 

Version - Front View

 

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