[MPlayer-dev-eng] Opportunity for list members (w/ attach)

[Jeff Gladnick]

Jan Knutar wrote:
> On Wednesday 22 September 2004 00:09, Jeff Gladnick wrote:
> 
>>1) Power will be supplied from li-ion batteries.
>>
>>2) would it really consume that much more power if the CheckForPeople() 
>>subroutine ran once every 30 seconds?
> 
> 
> Well, if it involves waking up the system, powering up USB bus for camera,
> etc, it might. I'm no expert though. To me, a hobbyist, I can think of a numerous
> ways off the top of my head to spend less than 3 bucks per unit for some photocell-
> like detection. Not including fancy presentation and installation, of course.

Well lets say the system is already on, but power is completely cut to 
the LCD.  Basically I want a box that can be popped in and out as 
quickly as possible.  We had some other ideas, laser from wall to wall, 
pressure sensor, etc.  However, the camera is already built into the 
system and I figure that would be cheaper in the long run.  I am still 
open to other ideas.

> 
> In a gondola you'd also have the problem of intensive background light interfering
> from all the pretty scenery :) Can be worked around in clever software of course...
> Maybe just coupling the "activation" with a sensor for gondola-at-station and a
> gondola-door-opened sensor would work, assuming it has a door, and that the door
> wouldn't be needlessly opened, etc.

Unfortunately the gondola door opens every time it reaches the station, 
whether people get in or not, so thats out.  I hadn't considered 
extremely bright relfections from mountains.  I am hoping that black on 
white contrast will be enough that it can be seen even in extremely 
direct sunlight.

> 
> Of course, whether a ready-made already existing unit complete with camera and all
> would be cheaper to develop and debug software for, to work in these conditions,
> than interfacing and writing some software for a simple hardware sensor, I can't really
> tell.

I will have to wait for my bid's to get back :)

> 
> 
>>3) The controlled environment is the inside of a gondola, as in a ski 
>>resort gondola.  So controlled, yes, power access, no.  Any ideas for 
>>howto detect that a person has entered the gondola in the cheapest 
>>fashion possible are welcome!
> 
> 
> If starting from scratch I would probably myself use hardware sensors for
> the door and/or pressure switches for the seats.
> 
> Also, why Li-Ion? Would a large lead-acid on top of the gondole not be cheaper,
> or is Li-ion cheaper in the long run or what? I don't have any quotes for battery
> systems available, but atleast on hunch I would assume bog-standard car betteries
> are cheaper.
> 

Li-ion has the best size to power ration, especially compared to 
lead-acid.  Also, how many cycles can you get out of lead acid?  Does 
anyone know?  They are also extremely heavy and may have some tramway 
board issues about added weight.