components: a game of "what if"

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components: a game of "what if"

Werner Almesberger
We all know gta02-core hasn't made much progress lately. The main
reason was that the next steps depend on what components we will be
able to use, which is still uncertain.

I also have to admit that some of the delays weren't entirely
unwelcome for me personally, because I had all the reconstruction
work going on at my new home/office/lab and wouldn't have been able
to get much done anyway. This ordeal still isn't finished, but
interferences have decreased to a tolerable level.

To bring life to the project again, how about a little game of "what
if" ? Specifically, "what if we can source the components we need on
our own ?"

If we try to do this, what would change ?

- we'll need to buy a larger varietey of components, costing money
  for the purchase and for shipping, (*)

- we'll need to find ways to obtain components the usual
  distributors don't have or that require a large minimum order,

- the logistics for shipping and customs get more complicated, due
  to an increased number of shipments and sources,

- for those parts that are custom designs made for Openmoko, we'll
  either have to find substitutes, or we'll be limited to what is
  already in our possession,

(*) Component donations may be an option as well, but the overhead
    of getting a large number of suppliers to make such donations
    may be in no useful proportion to the actual values involved.

When the gta02-core project started, I didn't expect this approach to
be viable. A few things have changed since then, which make me more
optimistic. Among them:

- parts of the projected cost have disappeared, e.g., SMT, and there
  may be more. This allows money to be spent on other items, without
  driving the cost for the prototypes through the roof.

- for various suppliers from whom we probably need direct assistance,
  I wouldn't even have known where to start asking for help.
  Meanwhile, people I know have developed contacts there that may be
  useful.

- the search for replacements for parts already gone from FIC's
  stock went better than I had expected. In particular, we were able
  to find very close substitutes for various electromechanical
  components I had been doubtful about.

So I'm not promising this will work, but it's at least worth a try.

- Werner

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Re: components: a game of "what if"

Patryk Benderz
[cut]
> If we try to do this, what would change ?
Hi Werner,
I would add one more point of doubt here: do you have enough storage
space to keep all these components, Sean will send you? Or will you ask
him to send components directly to university (of san Paulo?) which has
this SMT line?
[cut]

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Patryk "LeadMan" Benderz
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Re: components: a game of "what if"

Werner Almesberger
Patryk Benderz wrote:
> I would add one more point of doubt here: do you have enough storage
> space to keep all these components, Sean will send you? Or will you ask
> him to send components directly to university (of san Paulo?) which has
> this SMT line?

Oh, storage space is by far the least of my worries :-) Components
usually come on strips of tape. This tape is usually wound on a
reel, which is what the SMT machines (pick and place) need.

A common reel size for small parts is 9.2 mm wide with a 180 mm
diameter. Let's round this up to 20 x 20 x 1 cm. That's a volume of
about 0.4 liter. So all the about 80 electrical components on our
FIC/Openmoko wish list, including some that need wider reels,
should fit in a volume of less than 50 liters.

Since the reels would be almost empty (a reel can hold hundreds if
not thousands of components while we need only a few of most of the
parts), also the weight would be low, probably less than 100 g per
reel. So roughly 8 kg for all the components.

Case parts, LCM, etc., eat a bit more space, maybe 0.5-1 liters for
everything that goes into a single device. So that would be another
10-20 liters of volume and maybe 4 kg of weight.

I think I could quite comfortably stow away parts for about ten
times the number of FreeRunners produced to date at my home without
feeling overly crowded ;-)

But I don't want any stuff sent to me. That wouldn't make sense.
First of all, it would be a royal pain to get any of this through
customs. Then there would be a 50+% customs fee. And then I would
have to get it all to Sao Paulo - same continent but different
country, with its own not so easy customs system.

No, all the parts would ideally go straight to the SMT line.

- Werner

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