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Anelok: the post-factual PCB (2/2)

Werner Almesberger werner at almesberger.net
Sun Feb 12 19:51:40 UTC 2017


The issues the fake PCB helped to identify so far:

1) a clearly visible issue is that the knob is too small to be 
operated with anything much larger than a toothpick. So I've 
given it a bit more room. However, more about this below.

2) the memory card is pushed up by the middle part. For this, let
me explain the stacking:

http://downloads.qi-hardware.com/people/werner/anelok/tmp/fake-pcb/exploded-parts.png

- the cover is a transparent piece that goes over the OLED panel,
  holding it in place and protecting it. The cover is glued to the
  top shell.

- the OLED panel is held laterally by the top shell. It is gently
  pushed against the cover by some elastic material on top of the
  PCB.

- the top shell is the main structure, as described in
  http://lists.en.qi-hardware.com/pipermail/discussion/2017-February/011046.html

- the PCB goes into the top shell

- the middle part goes below the PCB and has openings for the
  memory card header and the rfkill switch. The middle part shields
  the PCB from the outside world when the bottom cover is removed.

- the bottom cover is held with screws, and is removed for battery
  or memory card changes, or when operating the rfkill switch ...

  Hmm, while writing the last sentence, I realized that this makes
  the rfkill switch way too difficult to access. So I guess it has 
  to go back on the outside, where I had it in earlier versions.
  Funny how something that obvious can sit right before your eyes
  for weeks, without you noticing :-)

Anyway, the memory card header sticks through the middle part, and
this middle part provides a "floor" under the memory card. If that
floor is too high, that would interfere with the card. So, to allow
for more tolerances (from 0.15 mm to 0.35 mm), I made the floor
thinner (from 1.0 mm to 0.8 mm).

3) last but not least, I noticed that the USB receptacle, even if 
fake and made of weak plastic, nothing compared to the real metal 
piece, protruding over the edge of the PCB, a) makes it difficult to 
insert the PCB, and b) makes it nearly impossible to remove it again
without applying excessive violence.

So I've added an access channel in the side wall, to give the
receptacle a bit more room. (You can already see this in the exploded
parts picture, above.)

- Werner



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