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RE: Finally a cheap possible wearable solution?

Sounds like you need a switching regulator.  They take in a range of =
voltage (say 9-18V) and give you a good voltage out (say 12V, many can =
do a 5V and 12V) with a little bit of ripple that can be cleaned up with =
a couple caps.  Many companies make them, such as Acon, Datel, etc.

- Jason W Fox
- Electronics Engineer
- (202) 404-3736
- SPG, ENEWS, Code 5707
- Tactical Electronic Warfare Division, Naval Research Lab
- Washington, DC

-----Original Message-----
From: Jeremy [mailto:]
Sent: Monday, February 24, 2003 14:07=20
To: 
Subject: RE: Finaly a cheap possible wearable solution?

I was thinking about this this morning and I was
think that I would have to build some sort of voltage
"regulator", but I am not expert on batteries. even with
the 12v power supply... (which I assume is expecting 12
volts dc input) I would have to regulate the power from
the bats. I can't remember the information from my basic
electrical course.

I am going to do the same thing as you.. I am going to
start puchasing my parts run the puppy off AC till I get
linux working. I will probably get it all together in a
project box of some sort then worry about DC power.

I will post my parts list after work tonight.

-----Original Message-----
From: ben [mailto:]
Sent: Monday, February 24, 2003 9:44 AM
To: ; Konstantin V.
Subject: Re: Finaly a cheap possible wearable solution?

This is exactly what I'm currently working on (
http://wearables.blu.org/wear-hard-03/20039141.html ).  The biggest =
issue
I've encountered is powering the unit in a convenent fashion.

Even though it's very light compared to most ATX (or even most other
mini-ITX) systems, it's still a lot more power hungry than most of the
wearable projects I've seen evidence of actual being made usable.  A =
sample
system, with an Eden processor, a laptop HD, and slimline CD will =
consume
enough power, even while idle, that it will probably drain a 12v battery =
(10
1.2v C cells of 4000mAH or so) in a lot less that 5 hours, particularly =
if
you're also powering a display.  I haven't been able to find good power
consumption figures on the Epia M, or the C3 processors (not Eden), but =
I
suspect they would significantly increase power consumption.

The only way I've found that would theoretically power a the system for
about
6 hours (my goal), is using heavy SLA batteries (5-10 lbs to make it =
that
long, depending on your system's requirements).  These are also simpler =
to
charge, because you can safely keep them topped off.  I have yet to look
into
Li-Ion, but it might be a happy medium, with lower weight, and the =
ability
to
run a parallel circuit (lacking in NiCad & NiMH batteries).

As was mentioned in a reply to my post, most 12v power supplies are
expecting
a constant 12v, no more or less, which could give mean your system cuts =
out
before your batteries are fully discharged (since voltage drops as the
charge
diminishes), further diminishing battery run-time.  You could work =
around
this by using a system like the one described here
http://wearables.blu.org/wear-hard-03/20039093.html , which integrates a
charger, but you'd have to regulate the voltages yourself.

I've already begun ordering some components to build my system, although =
I'm
going to concentrate on getting it assembled and running off AC power,
before
I attempt any of my battery designs.

Please keep me updated with your progress.  I will continue to post mine =
to
this list, assuming it's of interest to anyone here (the size & weight =
I'm
working with make it more of a luggable than a wearable).

-ben

On Sunday 23 February 2003 14:23, Konstantin V. wrote:
> Hi guys/gals. Im very interested in the wearable computing and for =
some
> time I was interested in reading about it, because pc104 parts are =
kind of
> costy and unavailable were I live (Mexico).
>
> I kind of interested in building a wearable for myself but it needs to =
be
a
> cheap solution or mid range. Interestingly enough EPIA's mothereboards =
and
> particulary the Eden 5000 model looks kind of apealing for a wearable,
with
> footprint of 170x170 mm it is very small and its sells for a merely =
100
> USD, Integrating 500 MHz Cyrix CPU VGA/TV-OUT/LAN/Sound/USB and more. =
I
> think Linux runs well enough on this mobo but Im not totaly shure, the
main
> website is offline and I cant access it www.viavpsd.com , there is =
other
> sites like http://www.viaarena.com which discusses Via's Mini-ITX
> plataform. One link to Epia M series which is not the EPIA 5000 that =
I'm
> talking about but you can apritiate the size of Mini-ITX format
> http://www.viaarena.com/?PageID=3D187 I mean compare the functionality =
of
> EPIA 5000 board to an existing PC104 or SBC board and then compare =
prices.
> Im not into embedded and dont need a watchdog or data adquisition, =
just a
> fun little system to carry around with PIM/Word processing/maybe video
> capture(but that later)
>
> Now the TV-out NTSC/PAL is important because a cheap Head Mounted =
Display
> could be a Kopin CyberDisplay320, a monocolor 320x240 display costing
about
> 60 USD wich could be driven by a Motorola chip part number MCVVQ111, =
the
> documentation for the this display driver is explains how to build a
> prototype board and this way integrating it into a very nice and cheap
Head
> Mounted Display. Here is a link to a MageForge article about a covert
> CyberDisplay in sunglasses , courtecy of Mircea
>
https://securehost34.hrwebservices.net/~magefor/cgi-bin/view/Main/SunGlas=
se
>s (The issue here is to get the MCVVQ111, I havent seen it on sale
anywhere)
>
> I know it is low resolution and monocolor but I think it is a viabe
> solution and it will be light and cheap, also low power consuming, and =
at
> last but not least it is very very covertable.
>
> Thiking about power consuming, here is a mini power supply from
> http://www.mini-box.com/pw-60.htm wich is a very small power supply =
unit
> that fits directly in EPIA motherboard (u can download a video of the
> mounting process wich is simple but ilustrative), the supply uses 12 =
DC
> input and regulates the normal ATX psu outputs, proving 1 connector =
for a
> HD + 1 connector for Floppy and a small 5 volts connector.
>
> Now if anyone would calculate the amount of power drained by this
> motherboard +  (put usual hardware that goes in the mobo like notebook =
HD
+
> Memstick ) +  HMD + Input devices (Twiddler or mouse or maybe a PDA
> keyboard)  and evaluate how many battery packs (Li-Ion) would be =
needed to
> power the whole system for a reasonable amount of time, dont know, =
maybe 5
> hours continuosly. Would it be 'wearable' ?
>
> What do you think about it?
>
>
>
>
> ---------------------------------
> Do you Yahoo!?
> Yahoo! Tax Center - forms, calculators, tips, and more

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