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

Rigel Christian rigelc at gmail.com
Wed Dec 24 01:03:39 UTC 2008


nitpick:

luxeons are not the brightest LEDs available. the CREE XR-E emitters are
currently the leaders in the lumens-per-watt category.

On Tue, Dec 23, 2008 at 4:52 PM, Christie Dudley <longobord at gmail.com>wrote:

> 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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>
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