Re: Prob. a very basic Q re: capacitors

Joerg <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote in
news:nUJjk.34245$ZE5.880@xxxxxxxxxxxxxxxxxxxx:

Kris Krieger wrote:
Joerg <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote in
news:MsHjk.15101$cW3.10285@xxxxxxxxxxxxxxxxxxxx:

Rich Grise wrote:
On Mon, 28 Jul 2008 12:09:13 -0500, Kris Krieger wrote:

How is the flow of power out of a charged capacitor be controlled?
I've been loking at whatever circuit diagrams I can fond that use
supercapacitors as an energy source, and I'm not clear on whether
control is via the resistors, or transistors.
Supercaps are NOT an energy "source" - they'd be a storage medium,
at best, and they even suck at that.

A battery can store millions of times as much energy as a cap.

But it'll die of exhaustion pretty soon. a lot of stuff gets thrown
in the trash because the rechargeables are nearly dead and too
expensive to replace. Adding Cadmium and other goodies to the
landfills.


Yup, that aspect of them really bothers me. Plus, I personally have
a probably-irrational level of sheer annpoyance at ahving to replace
things all the time - light bulbs, batteries, and other stuff as well
;) I have this admittedly-bizarre notion that everything should last
for at least ten years <L!> Yeah, I know it's goofy, but there it is
;)


Same here. And the stuff I design usually _does_ last much longer than
10 years. Heck, the very first ultrasound machine I helped design over
20 years ago is still used and often traded:
http://www.steineredv.de/med/51/435/

Yikes!

And I'm here pouring over "how to make a bright solar light", heh.

Cool stuff, tho'. I'm not one who's particularly fascinated with using
things like iPhones, but in other regards, technology is fascinating - not
even teh uses, to me, as much as the creative thought-processes used in
first perceiving that somethign can be done, and then going through the
whole design process of how to do it. IT kind of blows me away so to
speak.


Another where I designed parts of in the early 90's is the same.
Talked to the CEO recently and he said that they still service a lot
of them. The only things that "break" is a worn out monitor and the
occasional power supply damage after lightning struck or something.
Kind of makes me glad.

YEah, I can see how it could be very satisfying to do something that people
use, and esp. something that helps makes people's lives better, over a
prolonged period of time :)


I am still using some tools in the lab that I built as a kid over 30
years ago, such as these:
http://www.analogconsultants.com/ng/images/oak2.jpg
For some reason none of this ever needed fixing.

Interesting stuff.
Not a big fan of "designed-in obsolescence", eh? ;)


At any rate, I'll design e bodies of my stained-glass tunits so that
the Solar "stuff" (it'll all be in/attached to the top/"lid") can be
removed, so that, if/when it dies, the main body of the stained-glass
piece can still be used as a candleholder or some other form of
decor. But I like the idea of a long-lived power source, so teh
capacitor-as-"battery" idea also appeals to me aesthetically in a
weird sort of wayI don't know how to explain.

But that's why I was wondering about "flow control". I still have
waaaay more knowledge-*gaps*, than knowledge, so I'm probably
thinking of this totally wrong, but if electricity is analagous to
waterh, with Volts as "water pressure" and current as "flow rate
(amount of water that goes through over a given period of time", I'm
trying to figure out whetehr/how somethign analagous to a "valve" can
be applied to the capacitor so that the energy is only allowed out
slowly, rather than pouring out all at once.

THat probably sounds woefully ignorant, and I still have a very long
way to gho in my learning, but I still think tht the "capacitor
rather than battery" idea is just too *nifty keen* <LOL!> to ignore
;) And I think it'd be just soooooo cool if I could actually pull
any of this off <L!>


I don't know much about super caps but I've heard that many of them
also have a tendency not to last forever.

I've read "10 years", although but that might just be "up tp 10 yrs" - I'm
not by any stretch of the imagine among the "cognoscenti"!, and I just
started reading about this idea withing the past few days, after coming
across it completely by accident.

To get the most energy from
them you'll need a switcher that can almost squeeze the last electrons
out even if the voltage dips below a volt. It also avoids the power
waste of any linear circuit.

Also, many super caps are meant for low current RAM backup, meaning
the Ri is way too high for any serious other use.


THanks for teh input - yes, the battery-powered systems are definitely
"tried and true", meaning, regardless of whatever additional bits I might
add on if I decide to try to get better brightness than average, the
fundamentals would remain the same, and they've proven to be eminently
workable. So that's what I'll be concentrating on, since the problems
associated with getting capacitors to "behave" so to speak like batteries
require more knowledge (and intuitive understanding) than I'll be able to
scquire, at least acquire in time to try to get some of these things made
by the Christmas shopping season.

OTOH, if I can actually get that figured out, who knows what could then
loom up out of the dark fog like some Frankenstein monster <LOL!>




.

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