[Noisebridge-discuss] An introduction, and a plea for help with electrical systems

[Christie Dudley]

>
> comments interspersed below.


So I'll do the same! :)


> On Tue, 2008-12-23 at 15:04 -0800, Christie Dudley wrote:
> > batteries to run them.  While the Luxeon packaging is pretty
> > attractive for fixed installations, it's not something I recommend an
> > artist drop that kind of money on.
>
> what is the purpose of the luxeon devices?
> what is meant by "display light"?


Luxeons are just high-end "name brand" LEDs.  "The brightest available"

one of the possible downsides
> of buying from scrapheaps and other such (e.g. ebay)
> is that you can't get enough of a particular thing
> to make a design cost-effective:


You obviously haven't shopped for LEDs on Ebay!  I've found exactly the same
part from exactly the same supplier every time I've gone to look for more.
It's not a "scrap heap" at all, so much as a channel for getting stuff out
of China.  I'd encourage you to check it out before disparaging it!


>   also, what's the reflectivity of the concrete
> (or whatever material used for the columns)? is
> it possible to add pigments and/or reflective
> sediments to improve the reflectivity of the
> columns?


Oooh!  Neat idea! I know someone who added a pearl pigment to a concrete
finish to give it a fancy glow.  It takes some skill to get right, though.

  great idea! even though this runs counter to the
> don't-buy-onesy-twoesy ideas (above), it works
> because getting lots of 12VDC batteries is easy and
> it doesn't matter their capacity, just that their
> form-factor is within the space limits.


Yeah.  I imagine you could use lantern batteries as well.  If different
columns have different power needs, then we can probably work around that.

> Although I'd be a bit concerned about fitting them inside a 5" column.
> > They really should sit flat.  You could potentially use smaller
> > batteries if you got the power requirements down, but that's really
> > dependent on how much illumination you'll need, and how it's
> > distributed.  Lighting design probably should be something that
> > involves sitting down with drawings, etc. etc.
>
>    more good points. batteries should be upright.
> there are sealed batteries, but although they
> don't (normally) allow seepage, their internals
> are essentially the same as unsealed batteries:
> the chemical solution is in a cell that should
> be normally oriented (upright).
>   again, you can stack multiple small batteries
> within the columns' internal cavities, and the
> batteries can be different sizes as long as
> they're all the same voltage.


eeek!  That concerns me.  I wouldn't "mix and match" battery types.  I guess
you're a lot more confident with dealing with problems of uneven drainage
and issues as one wears down and others in the array are still going.  I'm
assuming you've dealt with this a lot in the past?  I'd be interested in
talking with you about the circuitry involved.  (Power diodes leading into
the array, etc. etc.?)

At this point I'm assuming these are going to be charged elsewhere.  A puny
solar panel could be used for each column, but how much could you really get
out of that?  Would it be worth the cost?  Convenience suggests the fewer
number of batteries per column, the easier it is to swap them out.  (And the
higher amp-hr/lb., the less to lug about.)

also, if batteries are used, you should know
> the temperature extremes, both hot and cold,
> in which they'll be working. that will have a
> bearing on power draw and recharging.


Yeah.  Here's where experience counts for a lot on playa.  I really wouldn't
go with anything that some other project in the past hasn't used. The playa
is a harsh environment, and this matters.

  seems the most important data point to nail
> down is the luminosity: how lit do the columns
> need to be to be seen from how far away? from
> that it seems you can figure power requirements.


Yep.  Lighting design must be done before the power can be calculated.

Christie

-- 
You can't learn what you think you already know.
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