Monday, September 26, 2016

How a stenomod is assembled

Stenomod, a keyboard for amateur stenography, is for sale. See my last blog post for details.

It's time to start telling the story of the stenomod. I'm gonna do it out of order though. Before I tell how I got here, I want to show where "here" is. I want to show how a stenomod is assembled.



Here you see the two unstuffed printed circuit boards. The left hand board is on a wooden deck used as a template. Those round holes make space for the pins of the key switches to poke through.The first thing to do is to stuff all the switches.


Those aluminum legs make the PCB into a temporary soldering platform. As you'll see, the double length legs on one side allow space for the the diode leads to hang down before being soldered.

Here I'm soldering the switches in.









Next we stuff the box connectors into each board.










And hold them in place with a rubber band while soldering.








The left hand board needs to have the micro-controller soldered in. It's an Arduino Metro Mini, and comes with stake pins which we'll use to connect it to the stenomod board.





I cut the stake pins down to 2 and 6 pin pieces, insert them into the board and place the Arduino board onto them.








A rubber band holds the assembly together while soldering, both top and bottom.




The only things left to solder now are the diodes. Bend them with pliers and insert them, matching the black mark on the diode with the white mark on the board, to get the polarity right.






See how the leads dangle but don't touch the ground? I solder the diodes from the top to avoid having to secure them upside down.









Time to remove the temporary legs and snip off the leads.







The stake pins under the Arduino need to be snipped as well.



Now the finished boards can be put back in the template and the keycaps can be inserted.




That's it for the printed circuit boards.


Next time we'll make a cable to connect the two boards and a wooden deck to mount them on.





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