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Sci.Electronics.Basics -> Newbie Q. re: solar light/battery
There are 20 messages in this thread.
You are currently looking at messages 1 to 20.
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Author: Kris KriegerDate: 20:05 31-05-08
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Hello, Group,
I'm trying to figure out how to buils a solar light (I have a market for
stained-glass solar lights and, once I create them, I want to be able to
put bright LEDs into them, without relying on finding cheap garden lights
that I then have to disassemble and reassemble...) (note that I'm a crafts
person, not an electronics person =:-o - I just want to do this one very
specific thing...at least for now ;) ).
Anyway, I've been looking at components, and one thing I've noticed is that
ther eare some very compact solar cells, but with much variation between
both Volt and milliAmp values. Since I want to charge a couple of NiMH
batteries, I'm confused as to whether I need to look for higher voltage, or
higher mA - I've looked all over the interent, and bought a couple of basic
books, so the circuit diagrams I've looked at at least now make some sense
to me, but there is nothing that clarifies exactly how to match everything
up so as to end up with a solar-powered light using LEDs. I'd like to use
one to four, but not more than 4, at this point.
I've looked at the circuits on-line, and tried disassembling a light, but
it's no more clear to me how exactly to match it all up, and how to
determine which solar cell to match with which batteries.
A clue would be very much appreciated ;)
TIA!
- Kris
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Author: JeffMDate: 23:25 31-05-08
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Kris Krieger wrote:
>I'm trying to figure out how to [build] a solar light
>(I have a market for stained-glass solar lights and,[...]
>(note that I'm a crafts person, not an electronics person
Like most people who find themselves
attacked from behind by a wild hare,
it appears you haven't actually thought this through.
The first step in a project is writing a specification.
Will the lights come on automatically?
Are you going to use *multiple* LEDs in each one?
Have you selected a LED to use?
Do you understand the arithmetic involved with LEDs?
Once you understand how *those* part work
and can put some actual NUMBERS to your requirements,
then you can move on the *battery* part and the arithmetic there.
On that front, it seems foolish for a complete rookie
to try to *build* something that he can buy as a complete unit.
http://www.google.com/products?q=intitle:Solar+intitle:Battery-Charger&scoring=p&
;price=between&price1=1&num=100
You certainly won't be able to do it cheaper
than the pros who build them in large quantities.
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Author: CDESCDate: 00:27 01-06-08
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"JeffM" <jeffm_@email.com> wrote in message
news:01f59c1b-937c-4934-b7d0-08721fa9f9c5@d19g2000prm.googlegroups.com...
> Kris Krieger wrote:
>>I'm trying to figure out how to [build] a solar light
>>(I have a market for stained-glass solar lights and,[...]
>>(note that I'm a crafts person, not an electronics person
>
> Like most people who find themselves
> attacked from behind by a wild hare,
> it appears you haven't actually thought this through.
> The first step in a project is writing a specification.
Don't take it like if I would think this place is meant for peoples to laugh
their ass off on peoples who literally started their post with "I'm a newbie
and I need help" but I tend to take for this poor guy who, luckilly wasn't
stuck his head down in a wrecked car on the roadside providing the kind of
introduction you gave him.
-- Now to that guy. The best way to learn not to put salt in your eyes is to
know how bad it hurts -- Google your way to some electronic plans on solar
NiCD chargers, light sensors and how to do that switching. You'll get parts
for about $5 to $10 off eBay. Get a few different solar panels, a few
different kinds of leds and do the tests. Doing the maths is cool, but some
peoples did them and they're selling their product to walmart for about 3$
each because it literally sucks. Some think that they can get it right on
paper, never test anything, start the production based on theories and get
poor results.
Do your tests, find the right leds type and quantity for the illumination
you want and start from there.
;-)
>
> Will the lights come on automatically?
> Are you going to use *multiple* LEDs in each one?
> Have you selected a LED to use?
> Do you understand the arithmetic involved with LEDs?
>
> Once you understand how *those* part work
> and can put some actual NUMBERS to your requirements,
> then you can move on the *battery* part and the arithmetic there.
>
> On that front, it seems foolish for a complete rookie
> to try to *build* something that he can buy as a complete unit.
>
http://www.google.com/products?q=intitle:Solar+intitle:Battery-Charger&scoring=p&p
rice=between&price1=1&num=100
> You certainly won't be able to do it cheaper
> than the pros who build them in large quantities.
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Author: Tom BiasiDate: 08:27 01-06-08
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"Kris Krieger" <me@dowmuff.in> wrote in message
news:35KdnSmWPeVeetzVnZ2dnUVZ_qDinZ2d@earthlink.com...
> Hello, Group,
>
> I'm trying to figure out how to buils a solar light (I have a market for
> stained-glass solar lights and, once I create them, I want to be able to
> put bright LEDs into them, without relying on finding cheap garden lights
> that I then have to disassemble and reassemble...) (note that I'm a crafts
> person, not an electronics person =:-o - I just want to do this one very
> specific thing...at least for now ;) ).
>
> Anyway, I've been looking at components, and one thing I've noticed is
> that
> ther eare some very compact solar cells, but with much variation between
> both Volt and milliAmp values. Since I want to charge a couple of NiMH
> batteries, I'm confused as to whether I need to look for higher voltage,
> or
> higher mA - I've looked all over the interent, and bought a couple of
> basic
> books, so the circuit diagrams I've looked at at least now make some sense
> to me, but there is nothing that clarifies exactly how to match everything
> up so as to end up with a solar-powered light using LEDs. I'd like to use
> one to four, but not more than 4, at this point.
>
> I've looked at the circuits on-line, and tried disassembling a light, but
> it's no more clear to me how exactly to match it all up, and how to
> determine which solar cell to match with which batteries.
>
> A clue would be very much appreciated ;)
>
> TIA!
>
> - Kris
>
>
>
>
>
In addition to what was already said,
You stated that you wanted to charge NiMH, do some research, these batteries
do not charge easily.
Tom
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Author: Kris KriegerDate: 11:02 01-06-08
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JeffM <jeffm_@email.com> wrote in
news:01f59c1b-937c-4934-b7d0-08721fa9f9c5@d19g2000prm.googlegroups.com:
> Kris Krieger wrote:
>>I'm trying to figure out how to [build] a solar light
>>(I have a market for stained-glass solar lights and,[...]
>>(note that I'm a crafts person, not an electronics person
>
> Like most people who find themselves
> attacked from behind by a wild hare,
> it appears you haven't actually thought this through.
> The first step in a project is writing a specification.
>
> Will the lights come on automatically?
I thought that was assumed by "solar light"...
> Are you going to use *multiple* LEDs in each one?
Between one and four, as Imentioned, depending upon the various things I
construct, but a general rule that coudl be applied to multiples would be
great ;)
> Have you selected a LED to use?
> Do you understand the arithmetic involved with LEDs?
Yes.
>
> Once you understand how *those* part work
> and can put some actual NUMBERS to your requirements,
> then you can move on the *battery* part and the arithmetic there.
>
> On that front, it seems foolish for a complete rookie
> to try to *build* something that he can buy as a complete unit.
I stated the reason. It's not relevant, tho', why I want to do it - IMO,
it's sufficient that I *do* want to do it.
I mean, why does anyone want to do anything? I make a lot fo my own
things, for several reasons, the main ones in this case being:
(1) *creative freedom* (able to make large or small things, as I choose
and/or as a client wishes and still light them - remember where I said I
do stained glass?); (2) it's not all that straightforward to take apart a
purchased item and keep it intact and in working condition for
transferral to another thing - FYI, I already tried that; (3) it seems
absurdly wasteful to me to continually have to throw away the entire
housing - if I make 100 units, for example, that's 100 complete housings
that go into the trash.
There are more reasons I want to do it myself, but those are the top 3.
> http://www.google.com/products?q=intitle:Solar+intitle:Battery-Charger&;
> scoring=p&price=between&price1=1&num=100 You certainly won't be able
> to do it cheaper than the pros who build them in large quantities.
>
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Author: Tom BiasiDate: 11:15 01-06-08
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"Kris Krieger" <me@dowmuff.in> wrote in message
news:aPKdnRD8MepgJN_VnZ2dnUVZ_qDinZ2d@earthlink.com...
> JeffM <jeffm_@email.com> wrote in
> news:01f59c1b-937c-4934-b7d0-08721fa9f9c5@d19g2000prm.googlegroups.com:
>
>> Kris Krieger wrote:
>>>I'm trying to figure out how to [build] a solar light
>>>(I have a market for stained-glass solar lights and,[...]
>>>(note that I'm a crafts person, not an electronics person
>>
>> Like most people who find themselves
>> attacked from behind by a wild hare,
>> it appears you haven't actually thought this through.
>> The first step in a project is writing a specification.
>>
>> Will the lights come on automatically?
>
> I thought that was assumed by "solar light"...
>
>
>> Are you going to use *multiple* LEDs in each one?
>
> Between one and four, as Imentioned, depending upon the various things I
> construct, but a general rule that coudl be applied to multiples would be
> great ;)
>
>> Have you selected a LED to use?
>> Do you understand the arithmetic involved with LEDs?
>
> Yes.
>
>>
>> Once you understand how *those* part work
>> and can put some actual NUMBERS to your requirements,
>> then you can move on the *battery* part and the arithmetic there.
>>
>> On that front, it seems foolish for a complete rookie
>> to try to *build* something that he can buy as a complete unit.
>
> I stated the reason. It's not relevant, tho', why I want to do it - IMO,
> it's sufficient that I *do* want to do it.
>
> I mean, why does anyone want to do anything? I make a lot fo my own
> things, for several reasons, the main ones in this case being:
> (1) *creative freedom* (able to make large or small things, as I choose
> and/or as a client wishes and still light them - remember where I said I
> do stained glass?); (2) it's not all that straightforward to take apart a
> purchased item and keep it intact and in working condition for
> transferral to another thing - FYI, I already tried that; (3) it seems
> absurdly wasteful to me to continually have to throw away the entire
> housing - if I make 100 units, for example, that's 100 complete housings
> that go into the trash.
>
> There are more reasons I want to do it myself, but those are the top 3.
>
>
>
>> http://www.google.com/products?q=intitle:Solar+intitle:Battery-Charger&;
>> scoring=p&price=between&price1=1&num=100 You certainly won't be
able
>> to do it cheaper than the pros who build them in large quantities.
>>
>
Kris,
No need to justify why you want to make it yourself.
I make my own beer and bake my own bread. Why, I can buy both cheaper?
Because I like to!
Sometimes people post here for info on how to build something when in fact
what they desire is a finished product and they think that it can be built
cheaper.
It usually cannot be built cheaper, but sometimes it can be built better, at
least a better fit to your application.
May I suggest that you find a commercial product that you like and post the
specs here. The guts can be obtained or constructed to meet you application.
Tom
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Author: Kris KriegerDate: 11:23 01-06-08
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"CDESC" <feedback@realitymedias.com> wrote in
news:pyp0k.98680$yT4.152040@wagner.videotron.net:
>
> "JeffM" <jeffm_@email.com> wrote in message
> news:01f59c1b-937c-4934-b7d0-08721fa9f9c5@d19g2000prm.googlegroups.com.
> ..
>> Kris Krieger wrote:
>>>I'm trying to figure out how to [build] a solar light
>>>(I have a market for stained-glass solar lights and,[...]
>>>(note that I'm a crafts person, not an electronics person
>>
>> Like most people who find themselves
>> attacked from behind by a wild hare,
>> it appears you haven't actually thought this through.
>> The first step in a project is writing a specification.
>
>
> Don't take it like if I would think this place is meant for peoples to
> laugh their ass off on peoples who literally started their post with
> "I'm a newbie and I need help" but I tend to take for this poor guy
> who, luckilly wasn't stuck his head down in a wrecked car on the
> roadside providing the kind of introduction you gave him.
THanks, I've learned (after 50+ years <LOL!> that thre are some people who
are just naysayers who don't erally want to offer information. Maybe they
figure it'd "threaten their status" in some way?, I dunno <shrug>. I
certainly didn't get the whole "wild hare" thing - maybe the OP is a bunny-
brain, dunno <shrug>. As people, naysayers are mostly like fleas -
annoying but otherwise utterly irrelevant.
At any rate:
> -- Now to that guy. The best way to learn not to put salt in your eyes
> is to know how bad it hurts -- Google your way to some electronic
> plans on solar NiCD chargers, light sensors and how to do that
> switching. You'll get parts for about $5 to $10 off eBay. Get a few
> different solar panels, a few different kinds of leds and do the
> tests. Doing the maths is cool, but some peoples did them and they're
> selling their product to walmart for about 3$ each because it
> literally sucks. Some think that they can get it right on paper, never
> test anything, start the production based on theories and get poor
> results.
>
> Do your tests, find the right leds type and quantity for the
> illumination you want and start from there.
>
> ;-)
>
>
Yeah, I do get a bunch of circuit diagrame on-line, and the 2 books I got
are enough of a refresher of what I remember from physics (yes, they *did*
have electricity when I was in University <L!>) THe batteries I got are
Malibu High Capacity NiMh, 1.2 V and 1500 mA, and the package says "Solar
fixture will automatically recharge new batteries; a charger giving a
consistent current of 150 mA for 14 hours may also be used". But I don't
know how that relates to solar cells.
THing is that I need to primarily make the glass parts - that'll be the
income-generator. I want to be able to plop in a simple soalr light,
nothing fancy. I have the formulae for capicitance, resistance, Ohm's law,
and so on, have diassembled on light and looked at the pics of other's
peole's disassemblies of solar garden lights, and so on, so a lot of it is
starting to makes sense (I've been doing this fairly steadily for several
days). But the solar cells - ideally, I'd want the abtteries to charge
quickly - the above-mentioned package info of 14 hours is completely
ridiculous - but I don't know how to match up sell an dbattery voltage and
current. Like, can I use a cell with higher voltage and more than 150 mA?
That sort of thing.
Buying a charger and disassembling it is expensive, and won't give me a
rule I can apply to other units...
>>
>> Will the lights come on automatically?
>> Are you going to use *multiple* LEDs in each one?
>> Have you selected a LED to use?
>> Do you understand the arithmetic involved with LEDs?
>>
>> Once you understand how *those* part work
>> and can put some actual NUMBERS to your requirements,
>> then you can move on the *battery* part and the arithmetic there.
>>
>> On that front, it seems foolish for a complete rookie
>> to try to *build* something that he can buy as a complete unit.
>> http://www.google.com/products?q=intitle:Solar+intitle:Battery-Charger
>> &scoring=p&price=between&price1=1&num=100 You certainly won't
be able
>> to do it cheaper than the pros who build them in large quantities.
>
>
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On Sun, 1 Jun 2008, Kris Krieger wrote:
>> On that front, it seems foolish for a complete rookie
>> to try to *build* something that he can buy as a complete unit.
>
> I stated the reason. It's not relevant, tho', why I want to do it - IMO,
> it's sufficient that I *do* want to do it.
>
But. the relevance of the comment is because of a "cold" post.
People post here all the time, and they leave out details. They ask
for something very specific, but then it turns out that's because they've
based that on a false assumption. Without detail, we have to interpret,
and many times it's not obvious if the poster asking the question knows
what he's doing, or doesn't.
There's nothing wrong with wanting to build rather than buy.
But, lots of times people ask about how to build something because they
don't realize it's available off the shelf. They can still proceed to
build it, but it should be tempered by an awareness that such things
are available.
So someone asks how to build an alarm clock. They want to put it
in a box and use it for some specific purpose. Do they really need
to build one, or can they get by with buying a used clock radio and
stripping out the clock? It really depends on whether their first
goal is getting results or building something. It usually isn't clear
if they've even considered an existing clock radio (and even though
salvaging parts is a time honored thing, the beginner often seems
to overlook scrap electronics as a source of parts, rushing to the
parts store with the list of parts out of the article and paying
premium prices as a result).
And forget about the building versus buying, buying some existing
piece of equipment can often be faster and maybe cheaper means of
getting some parts. If you have to track down a multi-pin IC to
build that clock, the closest and cheapest source will be the clock
radio, and once you've got that, one has to rethink whether it's
really valid to extract the IC and build around it, or just use
the clock radio as a source of a the "clock module".
Sometimes you can't get parts via consumer electronics, because
the parts are too specific and don't show up in such equipment. But
consumer electronics can often be a great source of components
that are hard to track down even if they are commonly used in consumer
electronics equipment.
This is especially so when talking about buying things at rummage or
garage sales. Then the price often drops to almost nothing, which can
really beat buying the parts new.
We had some of those garden lights, they all broke during this winter's
heavey snowfall. So I got a set of solar cells, and some reaonably
bright white LEDs, the nicads and even the circuitry to make them
all work. Maybe it wouldn't be the best choice to buy them to get
the solar cells, but I suddenly have some without having to fuss at
all. If I was building something in single quantities, I would have
to evaluate the ease of getting them that way compared to finding
a place that sells them and will sell to me and the cost of
the full order to get them.
Michael
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Author: Kris KriegerDate: 14:47 01-06-08
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Author: Kris KriegerDate: 15:03 01-06-08
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"Tom Biasi" <tombiasi@optonline.net> wrote in
news:hfadneT_1MaWIN_VnZ2dnUVZ_vednZ2d@giganews.com:
>
> "Kris Krieger" <me@dowmuff.in> wrote in message
> news:aPKdnRD8MepgJN_VnZ2dnUVZ_qDinZ2d@earthlink.com...
>> JeffM <jeffm_@email.com> wrote in
>> news:01f59c1b-937c-4934-b7d0-08721fa9f9c5@d19g2000prm.googlegroups.com
>> :
>>
>>> Kris Krieger wrote:
>>>>I'm trying to figure out how to [build] a solar light
>>>>(I have a market for stained-glass solar lights and,[...]
>>>>(note that I'm a crafts person, not an electronics person
>>>
>>> Like most people who find themselves
>>> attacked from behind by a wild hare,
>>> it appears you haven't actually thought this through.
>>> The first step in a project is writing a specification.
>>>
>>> Will the lights come on automatically?
>>
>> I thought that was assumed by "solar light"...
>>
>>
>>> Are you going to use *multiple* LEDs in each one?
>>
>> Between one and four, as Imentioned, depending upon the various
>> things I construct, but a general rule that coudl be applied to
>> multiples would be great ;)
>>
>>> Have you selected a LED to use?
>>> Do you understand the arithmetic involved with LEDs?
>>
>> Yes.
>>
>>>
>>> Once you understand how *those* part work
>>> and can put some actual NUMBERS to your requirements,
>>> then you can move on the *battery* part and the arithmetic there.
>>>
>>> On that front, it seems foolish for a complete rookie
>>> to try to *build* something that he can buy as a complete unit.
>>
>> I stated the reason. It's not relevant, tho', why I want to do it -
>> IMO, it's sufficient that I *do* want to do it.
>>
>> I mean, why does anyone want to do anything? I make a lot fo my own
>> things, for several reasons, the main ones in this case being:
>> (1) *creative freedom* (able to make large or small things, as I
>> choose and/or as a client wishes and still light them - remember
>> where I said I do stained glass?); (2) it's not all that
>> straightforward to take apart a purchased item and keep it intact and
>> in working condition for transferral to another thing - FYI, I
>> already tried that; (3) it seems absurdly wasteful to me to
>> continually have to throw away the entire housing - if I make 100
>> units, for example, that's 100 complete housings that go into the
>> trash.
>>
>> There are more reasons I want to do it myself, but those are the top
>> 3.
>>
>>
>>
>>> http://www.google.com/products?q=intitle:Solar+intitle:Battery-Charge
>>> r& scoring=p&price=between&price1=1&num=100 You certainly
won't be
>>> able to do it cheaper than the pros who build them in large
>>> quantities.
>>>
>>
>
> Kris,
> No need to justify why you want to make it yourself.
> I make my own beer and bake my own bread. Why, I can buy both cheaper?
> Because I like to!
Oh, I never made it at home but we used to go to a great brew-your-own
place when we lived in Mississauga, ON. One taste is *more* than enough
explanation <LOL!>
> Sometimes people post here for info on how to build something when in
> fact what they desire is a finished product and they think that it can
> be built cheaper.
Oh, OK - no, ther are more soalr lights for sale on-line than you can
shake a proverbial stick at ;), I want to be able to put the lights into
my stained-glass constructs.
> It usually cannot be built cheaper, but sometimes it can be built
> better, at least a better fit to your application.
> May I suggest that you find a commercial product that you like and
> post the specs here. The guts can be obtained or constructed to meet
> you application.
>
> Tom
I'd frankly *really* like to be able to buy just to "guts" so to speak.
I've just had no luck finding such a thing with my searches (prob.
becasue I don't know which search terms to use - "particle physics" is
easy, "buy solar light innards" takes a bit more finesse <G!>)
THe problem with the "find one you like" is "what is available at Wal-
Mart" (becasue I can't afford to pay $22 per experiment). My impression
is that I can't use the 5V "super bright" LEDs because the batteries are
only 1.2V (and size of the widget is a consideration - the stained glass
is supposed to be the focus, not the solar assembly ;) ). There are IIRC
"ultra bright" LEDs that are described as 1.2V and 15mA to 20mA.
I just can't help but feel that there must be *some* sort fo formula, or
set of formulae, to match components, without taking a whole college
course in electronics - yes, I know I'm looking for something of a short
cut, or the "Cliff Notes Guide to Making Solar Lights"...OTOH, that's how
i learn best, i.e., by focusing on a goal, and then looking up what I
need to so as to acheive it. THat's how I taught myself 3D modeling,
Classical Guitar, Russian, and most of the other things I know (learned
ratehr little via formal classes, i.e. school or even University).
I'm still looking up things on-line, and I did find this tutorial just
today:
http://www.instructables.com/id/Solar-Battery-Charging/
THe parts list includes LEDs, so I'm hoping that thsi ekind person who
generously made and uploaded the'charging' tutorial also loaded up a part
about "how to insert the LED stuff into the charging circuit" ;)
But paying who-knows-how-much to find a soalr light Ilike isn't really an
option - I want/need to make some $$, not lose $$...also, as Imight have
mentioned (or not, I've forgotten), if I get around to making a large
stained-glass piece, but haven't learned the concepts/formulae/etc.
necessaryto assemble the lighting, I'll have to go through the whole
process all over again. So it's kind of like that proverb, "Give a man a
fish, and you feed him for a day; teach a man to fish, and you feed him
for life" ;)
Meanwhile, if I find more tutorials, I'll post the links, jsut in case
someone else has similar questions but is too shy to ask ;)
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Author: Tom BiasiDate: 15:25 01-06-08
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"Kris Krieger" <me@dowmuff.in> wrote in message
news:7bednbrykNIBb9_VnZ2dnUVZ_r6rnZ2d@earthlink.com...
> "Tom Biasi" <tombiasi@optonline.net> wrote in
> news:hfadneT_1MaWIN_VnZ2dnUVZ_vednZ2d@giganews.com:
>
>>
>> "Kris Krieger" <me@dowmuff.in> wrote in message
>> news:aPKdnRD8MepgJN_VnZ2dnUVZ_qDinZ2d@earthlink.com...
>>> JeffM <jeffm_@email.com> wrote in
>>> news:01f59c1b-937c-4934-b7d0-08721fa9f9c5@d19g2000prm.googlegroups.com
>>> :
>>>
>>>> Kris Krieger wrote:
>>>>>I'm trying to figure out how to [build] a solar light
>>>>>(I have a market for stained-glass solar lights and,[...]
>>>>>(note that I'm a crafts person, not an electronics person
>>>>
>>>> Like most people who find themselves
>>>> attacked from behind by a wild hare,
>>>> it appears you haven't actually thought this through.
>>>> The first step in a project is writing a specification.
>>>>
>>>> Will the lights come on automatically?
>>>
>>> I thought that was assumed by "solar light"...
>>>
>>>
>>>> Are you going to use *multiple* LEDs in each one?
>>>
>>> Between one and four, as Imentioned, depending upon the various
>>> things I construct, but a general rule that coudl be applied to
>>> multiples would be great ;)
>>>
>>>> Have you selected a LED to use?
>>>> Do you understand the arithmetic involved with LEDs?
>>>
>>> Yes.
>>>
>>>>
>>>> Once you understand how *those* part work
>>>> and can put some actual NUMBERS to your requirements,
>>>> then you can move on the *battery* part and the arithmetic there.
>>>>
>>>> On that front, it seems foolish for a complete rookie
>>>> to try to *build* something that he can buy as a complete unit.
>>>
>>> I stated the reason. It's not relevant, tho', why I want to do it -
>>> IMO, it's sufficient that I *do* want to do it.
>>>
>>> I mean, why does anyone want to do anything? I make a lot fo my own
>>> things, for several reasons, the main ones in this case being:
>>> (1) *creative freedom* (able to make large or small things, as I
>>> choose and/or as a client wishes and still light them - remember
>>> where I said I do stained glass?); (2) it's not all that
>>> straightforward to take apart a purchased item and keep it intact and
>>> in working condition for transferral to another thing - FYI, I
>>> already tried that; (3) it seems absurdly wasteful to me to
>>> continually have to throw away the entire housing - if I make 100
>>> units, for example, that's 100 complete housings that go into the
>>> trash.
>>>
>>> There are more reasons I want to do it myself, but those are the top
>>> 3.
>>>
>>>
>>>
>>>> http://www.google.com/products?q=intitle:Solar+intitle:Battery-Charge
>>>> r& scoring=p&price=between&price1=1&num=100 You
certainly won't be
>>>> able to do it cheaper than the pros who build them in large
>>>> quantities.
>>>>
>>>
>>
>> Kris,
>> No need to justify why you want to make it yourself.
>> I make my own beer and bake my own bread. Why, I can buy both cheaper?
>> Because I like to!
>
> Oh, I never made it at home but we used to go to a great brew-your-own
> place when we lived in Mississauga, ON. One taste is *more* than enough
> explanation <LOL!>
>
>> Sometimes people post here for info on how to build something when in
>> fact what they desire is a finished product and they think that it can
>> be built cheaper.
>
> Oh, OK - no, ther are more soalr lights for sale on-line than you can
> shake a proverbial stick at ;), I want to be able to put the lights into
> my stained-glass constructs.
>
>> It usually cannot be built cheaper, but sometimes it can be built
>> better, at least a better fit to your application.
>> May I suggest that you find a commercial product that you like and
>> post the specs here. The guts can be obtained or constructed to meet
>> you application.
>>
>> Tom
>
> I'd frankly *really* like to be able to buy just to "guts" so to speak.
> I've just had no luck finding such a thing with my searches (prob.
> becasue I don't know which search terms to use - "particle physics" is
> easy, "buy solar light innards" takes a bit more finesse <G!>)
>
> THe problem with the "find one you like" is "what is available at
Wal-
> Mart" (becasue I can't afford to pay $22 per experiment). My impression
> is that I can't use the 5V "super bright" LEDs because the batteries are
> only 1.2V (and size of the widget is a consideration - the stained glass
> is supposed to be the focus, not the solar assembly ;) ). There are IIRC
> "ultra bright" LEDs that are described as 1.2V and 15mA to 20mA.
>
> I just can't help but feel that there must be *some* sort fo formula, or
> set of formulae, to match components, without taking a whole college
> course in electronics - yes, I know I'm looking for something of a short
> cut, or the "Cliff Notes Guide to Making Solar Lights"...OTOH, that's how
> i learn best, i.e., by focusing on a goal, and then looking up what I
> need to so as to acheive it. THat's how I taught myself 3D modeling,
> Classical Guitar, Russian, and most of the other things I know (learned
> ratehr little via formal classes, i.e. school or even University).
>
> I'm still looking up things on-line, and I did find this tutorial just
> today:
> http://www.instructables.com/id/Solar-Battery-Charging/
>
> THe parts list includes LEDs, so I'm hoping that thsi ekind person who
> generously made and uploaded the'charging' tutorial also loaded up a part
> about "how to insert the LED stuff into the charging circuit" ;)
>
> But paying who-knows-how-much to find a soalr light Ilike isn't really an
> option - I want/need to make some $$, not lose $$...also, as Imight have
> mentioned (or not, I've forgotten), if I get around to making a large
> stained-glass piece, but haven't learned the concepts/formulae/etc.
> necessaryto assemble the lighting, I'll have to go through the whole
> process all over again. So it's kind of like that proverb, "Give a man a
> fish, and you feed him for a day; teach a man to fish, and you feed him
> for life" ;)
>
> Meanwhile, if I find more tutorials, I'll post the links, jsut in case
> someone else has similar questions but is too shy to ask ;)
>
>
>
Ok Kris,
One place to start would be to determine how much illumination you need.
Find LEDs that can give you that.
What voltage and current do you need to power the LEDs for the period of
time that you would like?
What battery can supply this?
What solar arrangement can charge the battery in the time that you want?
In short, design the project.
Tom
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Author: Kris KriegerDate: 15:31 01-06-08
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Michael Black <et472@ncf.ca> wrote in
news:Pine.LNX.4.64.0806011152470.27894@darkstar.example.org:
> On Sun, 1 Jun 2008, Kris Krieger wrote:
>
>>> On that front, it seems foolish for a complete rookie
>>> to try to *build* something that he can buy as a complete unit.
>>
>> I stated the reason. It's not relevant, tho', why I want to do it -
>> IMO, it's sufficient that I *do* want to do it.
>>
> But. the relevance of the comment is because of a "cold" post.
OK, but that whole bit about "attacked by a hare" (IOW, obvious
implication being "idiot") was silly. I've tutored a whole heck of a lot
of people in various subjects I do know, and the first thing I always
tell them is "There are no stupid questions"; the second thing I tell
everyone is "Nobody is born knowing everything - or anything at all, for
that matter - information always comes from someplace".
Lack of knowledge is nothing to be ashamed of, as long as one seeks to
continually learn new things ;)
>
> People post here all the time, and they leave out details.
Which is why I specified "I'm a newbie" and "I'm primarily a stained-
glass/crafts person, not an electronics person." Idid take physics 101
and 102 (at Rutgers U. - I was a science major), but that was a long time
ago, and it never included any of the type of work needed to build
electronic widgets.
> They ask
> for something very specific, but then it turns out that's because
> they've based that on a false assumption. Without detail, we have to
> interpret, and many times it's not obvious if the poster asking the
> question knows what he's doing, or doesn't.
>
> There's nothing wrong with wanting to build rather than buy.
Oh, I know! I make a lot of my own things, from bits of furniture, to
lamps, to drapes of all things, to a whole variety of other things. I
don't feel any need for support/approval/(not sure of the right word) to
do any of that; I just do what I do ;)
Mostly, I just hammer away at things until I "get" them, but this time, I
figured I'd do the "smart" thing and try to pose some questions.
Overall, I think I'm learning to prefer my old method...
>
> But, lots of times people ask about how to build something because
> they don't realize it's available off the shelf. They can still
> proceed to build it, but it should be tempered by an awareness that
> such things are available.
>
> So someone asks how to build an alarm clock. They want to put it
> in a box and use it for some specific purpose. Do they really need
> to build one, or can they get by with buying a used clock radio and
> stripping out the clock? It really depends on whether their first
> goal is getting results or building something. It usually isn't clear
> if they've even considered an existing clock radio (and even though
> salvaging parts is a time honored thing, the beginner often seems
> to overlook scrap electronics as a source of parts, rushing to the
> parts store with the list of parts out of the article and paying
> premium prices as a result).
>
> And forget about the building versus buying, buying some existing
> piece of equipment can often be faster and maybe cheaper means of
> getting some parts. If you have to track down a multi-pin IC to
> build that clock, the closest and cheapest source will be the clock
> radio, and once you've got that, one has to rethink whether it's
> really valid to extract the IC and build around it, or just use
> the clock radio as a source of a the "clock module".
>
> Sometimes you can't get parts via consumer electronics, because
> the parts are too specific and don't show up in such equipment. But
> consumer electronics can often be a great source of components
> that are hard to track down even if they are commonly used in consumer
> electronics equipment.
>
> This is especially so when talking about buying things at rummage or
> garage sales. Then the price often drops to almost nothing, which can
> really beat buying the parts new.
>
> We had some of those garden lights, they all broke during this
> winter's heavey snowfall. So I got a set of solar cells, and some
> reaonably bright white LEDs, the nicads and even the circuitry to make
> them all work. Maybe it wouldn't be the best choice to buy them to
> get the solar cells, but I suddenly have some without having to fuss
> at all. If I was building something in single quantities, I would
> have to evaluate the ease of getting them that way compared to finding
> a place that sells them and will sell to me and the cost of
> the full order to get them.
>
> Michael
>
While all of that is true, it's also tru that you cannot always find a
solar light for the oft-quoted proverbial five bucks - most esp. not one
that's worth a tinker's damn - the cheap one's I've seen are precisely
that, cheap, as in, crap - I don't want to sabotage my possible business
from the outset by using some cheap POS that will break down after a
couple months, like the cheap (and crappy) solar lights I bought
recently. If I'm going to bust my hump making (and charge an appropriate
price for) hand-crafted artful stained glass items, I want to put in a
solar component that will be long-lived.
A solar light isn't exotic, and I found sources all the parts on-line
already. As above, yes, I most certainly do *wish* I could just buy the
"innards" without the housing, most especially if I could find a
*relible* source, because, if my idea takes off, I might end up making a
lot of the items. Getting a couple cheap things on eBay is not what I
consider a reliable source. OTOH, once I can figure out how to match the
solar cell(s), abttery(or batteries), LED(s), and so on, IOW, once i knwo
the *components*, and how tehy match up, I'll know what to shop for, and
be able to find a source.
So, yup, buying the individual parts, I make a solar light for $18 to $22
bucks, as best as I can currently figure. And sure, ther are some cheap
POS ones out there I might be able to disassemble (tho' the cheap POS
thing I disassempled the other day was such a cheap POS that all the
components fell apart during the process). But "the absolute cheapest"
isn't the point, given what I want to do, as I'd described in my original
post.
But I'm still looking online and waiting for another book to arrive.
Eventually I'll figure it out...
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Author: Tom BiasiDate: 15:51 01-06-08
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Author: Kris KriegerDate: 17:41 01-06-08
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"Tom Biasi" <tombiasi@optonline.net> wrote in
news:AZidnZWHCu4jat_VnZ2dnUVZ_hqdnZ2d@giganews.com:
>
> "Kris Krieger" <me@dowmuff.in> wrote in message
> news:7bednbrykNIBb9_VnZ2dnUVZ_r6rnZ2d@earthlink.com...
>> "Tom Biasi" <tombiasi@optonline.net> wrote in
>> news:hfadneT_1MaWIN_VnZ2dnUVZ_vednZ2d@giganews.com:
>>
>>>
>>> "Kris Krieger" <me@dowmuff.in> wrote in message
>>> news:aPKdnRD8MepgJN_VnZ2dnUVZ_qDinZ2d@earthlink.com...
>>>> JeffM <jeffm_@email.com> wrote in
>>>> news:01f59c1b-937c-4934-b7d0-08721fa9f9c5@d19g2000prm.googlegroups.c
>>>> om
>>>> :
>>>>
>>>>> Kris Krieger wrote:
>>>>>>I'm trying to figure out how to [build] a solar light
>>>>>>(I have a market for stained-glass solar lights and,[...]
>>>>>>(note that I'm a crafts person, not an electronics person
>>>>>
>>>>> Like most people who find themselves
>>>>> attacked from behind by a wild hare,
>>>>> it appears you haven't actually thought this through.
>>>>> The first step in a project is writing a specification.
>>>>>
>>>>> Will the lights come on automatically?
>>>>
>>>> I thought that was assumed by "solar light"...
>>>>
>>>>
>>>>> Are you going to use *multiple* LEDs in each one?
>>>>
>>>> Between one and four, as Imentioned, depending upon the various
>>>> things I construct, but a general rule that coudl be applied to
>>>> multiples would be great ;)
>>>>
>>>>> Have you selected a LED to use?
>>>>> Do you understand the arithmetic involved with LEDs?
>>>>
>>>> Yes.
>>>>
>>>>>
>>>>> Once you understand how *those* part work
>>>>> and can put some actual NUMBERS to your requirements,
>>>>> then you can move on the *battery* part and the arithmetic there.
>>>>>
>>>>> On that front, it seems foolish for a complete rookie
>>>>> to try to *build* something that he can buy as a complete unit.
>>>>
>>>> I stated the reason. It's not relevant, tho', why I want to do it
>>>> - IMO, it's sufficient that I *do* want to do it.
>>>>
>>>> I mean, why does anyone want to do anything? I make a lot fo my
>>>> own things, for several reasons, the main ones in this case being:
>>>> (1) *creative freedom* (able to make large or small things, as I
>>>> choose and/or as a client wishes and still light them - remember
>>>> where I said I do stained glass?); (2) it's not all that
>>>> straightforward to take apart a purchased item and keep it intact
>>>> and in working condition for transferral to another thing - FYI, I
>>>> already tried that; (3) it seems absurdly wasteful to me to
>>>> continually have to throw away the entire housing - if I make 100
>>>> units, for example, that's 100 complete housings that go into the
>>>> trash.
>>>>
>>>> There are more reasons I want to do it myself, but those are the
>>>> top 3.
>>>>
>>>>
>>>>
>>>>> http://www.google.com/products?q=intitle:Solar+intitle:Battery-Char
>>>>> ge r& scoring=p&price=between&price1=1&num=100 You
certainly won't
>>>>> be able to do it cheaper than the pros who build them in large
>>>>> quantities.
>>>>>
>>>>
>>>
>>> Kris,
>>> No need to justify why you want to make it yourself.
>>> I make my own beer and bake my own bread. Why, I can buy both
>>> cheaper? Because I like to!
>>
>> Oh, I never made it at home but we used to go to a great
>> brew-your-own place when we lived in Mississauga, ON. One taste is
>> *more* than enough explanation <LOL!>
>>
>>> Sometimes people post here for info on how to build something when
>>> in fact what they desire is a finished product and they think that
>>> it can be built cheaper.
>>
>> Oh, OK - no, ther are more soalr lights for sale on-line than you can
>> shake a proverbial stick at ;), I want to be able to put the lights
>> into my stained-glass constructs.
>>
>>> It usually cannot be built cheaper, but sometimes it can be built
>>> better, at least a better fit to your application.
>>> May I suggest that you find a commercial product that you like and
>>> post the specs here. The guts can be obtained or constructed to meet
>>> you application.
>>>
>>> Tom
>>
>> I'd frankly *really* like to be able to buy just to "guts" so to
>> speak. I've just had no luck finding such a thing with my searches
>> (prob. becasue I don't know which search terms to use - "particle
>> physics" is easy, "buy solar light innards" takes a bit more
finesse
>> <G!>)
>>
>> THe problem with the "find one you like" is "what is available
at
>> Wal- Mart" (becasue I can't afford to pay $22 per experiment). My
>> impression is that I can't use the 5V "super bright" LEDs because the
>> batteries are only 1.2V (and size of the widget is a consideration -
>> the stained glass is supposed to be the focus, not the solar assembly
>> ;) ). There are IIRC "ultra bright" LEDs that are described as 1.2V
>> and 15mA to 20mA.
>>
>> I just can't help but feel that there must be *some* sort fo formula,
>> or set of formulae, to match components, without taking a whole
>> college course in electronics - yes, I know I'm looking for something
>> of a short cut, or the "Cliff Notes Guide to Making Solar
>> Lights"...OTOH, that's how i learn best, i.e., by focusing on a goal,
>> and then looking up what I need to so as to acheive it. THat's how I
>> taught myself 3D modeling, Classical Guitar, Russian, and most of the
>> other things I know (learned ratehr little via formal classes, i.e.
>> school or even University).
>>
>> I'm still looking up things on-line, and I did find this tutorial
>> just today:
>> http://www.instructables.com/id/Solar-Battery-Charging/
>>
>> THe parts list includes LEDs, so I'm hoping that thsi ekind person
>> who generously made and uploaded the'charging' tutorial also loaded
>> up a part about "how to insert the LED stuff into the charging
>> circuit" ;)
>>
>> But paying who-knows-how-much to find a soalr light Ilike isn't
>> really an option - I want/need to make some $$, not lose $$...also,
>> as Imight have mentioned (or not, I've forgotten), if I get around to
>> making a large stained-glass piece, but haven't learned the
>> concepts/formulae/etc. necessaryto assemble the lighting, I'll have
>> to go through the whole process all over again. So it's kind of like
>> that proverb, "Give a man a fish, and you feed him for a day; teach a
>> man to fish, and you feed him for life" ;)
>>
>> Meanwhile, if I find more tutorials, I'll post the links, jsut in
>> case someone else has similar questions but is too shy to ask ;)
>>
>>
>>
>
> Ok Kris,
> One place to start would be to determine how much illumination you
> need. Find LEDs that can give you that.
> What voltage and current do you need to power the LEDs for the period
> of time that you would like?
> What battery can supply this?
> What solar arrangement can charge the battery in the time that you
> want? In short, design the project.
> Tom
>
As mentioned, since the batteries are 1.2V and 1500mA, I assumet aht (1)
it's simplest to stick with a 1.2V LED which, if rted at 15mA, should
stay lit for the night.
I don't know what solar arrangement ebst acheives the charging; as
mentioned, I don't knwo whetehr I need to match the voltage of the solar
cellto the battery, what maximum mA the SC should have, or if it has too
many, how to damp charging once the battery is charged.
Again, tho', I'm slowly answering my own questions adn *will* eventually
figure it out. I also decided against posting any links, it seems that
the info would be far too elementary for this NG.
As per my other post, sorry to have been a bother.
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Author: Kris KriegerDate: 17:41 01-06-08
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"Tom Biasi" <tombiasi@optonline.net> wrote in
news:Yd-dnQBiscg2YN_VnZ2dnUVZ_qvinZ2d@giganews.com:
>
> "Kris Krieger" <me@dowmuff.in> wrote in message
> news:jtadnZ4sbrOzZN_VnZ2dnUVZ_t_inZ2d@earthlink.com...
>> Michael Black <et472@ncf.ca> wrote in
>> news:Pine.LNX.4.64.0806011152470.27894@darkstar.example.org:
>> OK, but that whole bit about "attacked by a hare" (IOW, obvious
>> implication being "idiot") was silly.
> SNIP>>>
>
> I have said much in all the sub paragraphs of this thread but need to
> say this:
> Perhaps you are not from the USA.
> The reference to the hare is not to imply that you are an idiot.
> It is a cleaver play on words to imply that you had an impulsive idea.
> Tom
>
>
>
I'm from the USA but I never heard anything about hares except for "hare-
brained", and the mockery that Pres. Carter got re: the rabbit incident.
Guess I lived in the wrong part of the US or perhaps the wrong side of the
tracks (or petroleum cracking plant as 't'were).
In any event, I seem to be slowly working out the answers to my questions
myself.
Sorry for having been a bother.
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Author: Peter BennettDate: 20:09 01-06-08
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On Sun, 01 Jun 2008 16:41:10 -0500, Kris Krieger <me@dowmuff.in>
wrote:
<much snippage>
>
>As mentioned, since the batteries are 1.2V and 1500mA, I assumet aht (1)
>it's simplest to stick with a 1.2V LED which, if rted at 15mA, should
>stay lit for the night.
The voltage across a lit LED depends primarily on the LED's colour -
red LEDs are about 1.7 volts, yellow 1.9 volts and green 2.1 volts.
Blue and white LEDs are 3.3 - 3.6 volts, I believe. (a white LED is
really a blue led with white phosphor, since a single LED chip can
only produce a single colour.) If you see an LED rated at 1.2 volts,
it will be infra-red - probably not much use to you (and it won't
work reliably off a 1.2 volt battery anyway, as the battery voltage
will drop as it discharges.
You will have to connect two or more batteries in series to operate
the LEDs, or have some electronics to step the 1.2 volts up to
something that will run the LEDs.
Since the voltage across an LED is determined by its chemistry/colour,
LEDs are normally run from a higher voltage than their rating, with a
series resistor to limit the current.
>
>I don't know what solar arrangement ebst acheives the charging; as
>mentioned, I don't knwo whetehr I need to match the voltage of the solar
>cellto the battery, what maximum mA the SC should have, or if it has too
>many, how to damp charging once the battery is charged.
>
>Again, tho', I'm slowly answering my own questions adn *will* eventually
>figure it out. I also decided against posting any links, it seems that
>the info would be far too elementary for this NG.
>
>As per my other post, sorry to have been a bother.
--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
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Author: John FieldsDate: 09:36 02-06-08
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On Sun, 01 Jun 2008 16:41:23 -0500, Kris Krieger <me@dowmuff.in>
wrote:
>"Tom Biasi" <tombiasi@optonline.net> wrote in
>news:Yd-dnQBiscg2YN_VnZ2dnUVZ_qvinZ2d@giganews.com:
>
>>
>> "Kris Krieger" <me@dowmuff.in> wrote in message
>> news:jtadnZ4sbrOzZN_VnZ2dnUVZ_t_inZ2d@earthlink.com...
>>> Michael Black <et472@ncf.ca> wrote in
>>> news:Pine.LNX.4.64.0806011152470.27894@darkstar.example.org:
>>> OK, but that whole bit about "attacked by a hare" (IOW, obvious
>>> implication being "idiot") was silly.
>> SNIP>>>
>>
>> I have said much in all the sub paragraphs of this thread but need to
>> say this:
>> Perhaps you are not from the USA.
>> The reference to the hare is not to imply that you are an idiot.
>> It is a cleaver play on words to imply that you had an impulsive idea.
>> Tom
>>
>>
>>
>
>I'm from the USA but I never heard anything about hares except for "hare-
>brained", and the mockery that Pres. Carter got re: the rabbit incident.
>Guess I lived in the wrong part of the US or perhaps the wrong side of the
>tracks (or petroleum cracking plant as 't'were).
>
>In any event, I seem to be slowly working out the answers to my questions
>myself.
>
>Sorry for having been a bother.
---
No bother at all. :)
The 'hare' crack was, I believe, a misspelled attempt at implying a
"wild _hair_ up your ass", and this _is_ sci.electronics.basics, where
you're right: There are no stupid questions here.
As far as the rest of it goes, first you have the LEDs, and assuming
they're common, garden-variety white, then they'll have a forward
voltage (Vf) of about 4V max at a forward current of 20mA.
Next are the cells, which will output 1.2V and, being rated at
1500mAH, will output 20mA for:
mAH 1500mAH
T = ----- = --------- = 20 hours
mA 20mA
Until the cell discharges to its terminal voltage, 1.0 to 1.1 volt.
Finally, there's the photovoltaic (PV) panel, which is rated to supply
some current into a load with some voltage across the load.
That load resistance can be determined from:
E
R = ---
I
Where R is the load resistance, in ohms,
E is the voltage across the load, in volts, and
I is the current through the load, in amperes.
Since the LEDs have a Vf(max) of 4V, then you'll need at least four
NiMh cells to build a 4.8V battery which can drive the LEDs.
For the single LED case" (View in Courier)
VBAT
/
+---------+
|+ |
[NiMH] |
| [Rs]
[NiMH] |
| |
[NiMH] |A
| [LED]
[NiMH] |
|- |
+---------+
and Rs will be equal to:
VBAT - Vf(min) 4.8V - 3.5V
Rs = ---------------- = ------------- = 65 ohms
If 0.02A
Note that Vf(min) was used for the LED's forward voltage.
The reason for that is to keep the current through the LED from
exceeding 20mA if its Vf is less than the maximum specified on the
data sheet.
Another caveat is that NiMH cells, when fully charged, will output
about 1.4V for a while, until they settle down to 1.2V, so it would be
possible for Vbat to be 5.6V initially.
Under those conditions, Rs should be equal to:
VBAT(max) - Vf(min) 5.6V - 3.5V
Rs = --------------------- = ------------- = 105 ohms
If 0.02A
100 ohms is a standard 5% value and would force the initial current,
under worst case conditions, through the LED to be:
VBAT(max) - Vf(min) 5.6V - 3.5V
If = --------------------- = ------------- = 0.021 amperes
Rs 100R
which would be fine, and the resistor would dissipate:
P = EI
=(VBAT(max) - Vf(min)) * If = 2.1V * 0.021A = 44 milliwatts
A standard 100 ohm +/- 5% 1/4 watt carbon film resistor would be fine.
More later on today...
JF
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Author: Kris KriegerDate: 11:48 02-06-08
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John Fields <jfields@austininstruments.com> wrote in
news:qpt744l7of2gbjc08f7bpsg2k5u89ngdg8@4ax.com:
Helpful Info
AND
Peter Bennett <peterbb@somewhere.invalid> wrote in
news:44e64459q1p7vrbnfqc8s9outmjgfjvha2@news.supernews.com:
VERY helpful info that answered a lot of my questions!
*Thank You!* to you both. I was about to unsubscribe and figured I'd do
one last check-in.
Your information, esp. John's excellent post!, helped clarify, and give a
cohesive framework to, the umpteen different sources I've gathered and
printed out regarding the circuits and components. I've been looking up
info online for several days, and cut'n'pasting images and text into Word
(the Jurassic version <g!>) to create a printed reference that I can
scribble on (and whose pages I can spred over the floor so as to compare
them).
So I'll print out both you rposts and go over it all, together with my
various other references. I've become pigheadedly determined to learn to
do this, one way or another ;)
Thanks again to both of you!
Now off to do some comparative reading -
- Kris
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Author: John FieldsDate: 18:34 02-06-08
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On Mon, 02 Jun 2008 08:36:57 -0500, John Fields
<jfields@austininstruments.com> wrote:
>On Sun, 01 Jun 2008 16:41:23 -0500, Kris Krieger <me@dowmuff.in>
>wrote:
>
>>"Tom Biasi" <tombiasi@optonline.net> wrote in
>>news:Yd-dnQBiscg2YN_VnZ2dnUVZ_qvinZ2d@giganews.com:
>>
>>>
>>> "Kris Krieger" <me@dowmuff.in> wrote in message
>>> news:jtadnZ4sbrOzZN_VnZ2dnUVZ_t_inZ2d@earthlink.com...
>>>> Michael Black <et472@ncf.ca> wrote in
>>>> news:Pine.LNX.4.64.0806011152470.27894@darkstar.example.org:
>>>> OK, but that whole bit about "attacked by a hare" (IOW,
obvious
>>>> implication being "idiot") was silly.
>>> SNIP>>>
>>>
>>> I have said much in all the sub paragraphs of this thread but need to
>>> say this:
>>> Perhaps you are not from the USA.
>>> The reference to the hare is not to imply that you are an idiot.
>>> It is a cleaver play on words to imply that you had an impulsive idea.
>>> Tom
>>>
>>>
>>>
>>
>>I'm from the USA but I never heard anything about hares except for "hare-
>>brained", and the mockery that Pres. Carter got re: the rabbit incident.
>>Guess I lived in the wrong part of the US or perhaps the wrong side of the
>>tracks (or petroleum cracking plant as 't'were).
>>
>>In any event, I seem to be slowly working out the answers to my questions
>>myself.
>>
>>Sorry for having been a bother.
>
>---
>No bother at all. :)
>
>The 'hare' crack was, I believe, a misspelled attempt at implying a
>"wild _hair_ up your ass", and this _is_ sci.electronics.basics, where
>you're right: There are no stupid questions here.
>
>
>As far as the rest of it goes, first you have the LEDs, and assuming
>they're common, garden-variety white, then they'll have a forward
>voltage (Vf) of about 4V max at a forward current of 20mA.
>
>Next are the cells, which will output 1.2V and, being rated at
>1500mAH, will output 20mA for:
>
> mAH 1500mAH
> T = ----- = --------- = 20 hours
> mA 20mA
>
>Until the cell discharges to its terminal voltage, 1.0 to 1.1 volt.
>
>Finally, there's the photovoltaic (PV) panel, which is rated to supply
>some current into a load with some voltage across the load.
>
>That load resistance can be determined from:
>
> E
> R = ---
> I
>
>Where R is the load resistance, in ohms,
> E is the voltage across the load, in volts, and
> I is the current through the load, in amperes.
>
>
>Since the LEDs have a Vf(max) of 4V, then you'll need at least four
>NiMh cells to build a 4.8V battery which can drive the LEDs.
>
>For the single LED case" (View in Courier)
>
> VBAT
> /
> +---------+
> |+ |
> [NiMH] |
> | [Rs]
> [NiMH] |
> | |
> [NiMH] |A
> | [LED]
> [NiMH] |
> |- |
> +---------+
>
>and Rs will be equal to:
>
> VBAT - Vf(min) 4.8V - 3.5V
> Rs = ---------------- = ------------- = 65 ohms
> If 0.02A
>
>Note that Vf(min) was used for the LED's forward voltage.
>
>The reason for that is to keep the current through the LED from
>exceeding 20mA if its Vf is less than the maximum specified on the
>data sheet.
>
>Another caveat is that NiMH cells, when fully charged, will output
>about 1.4V for a while, until they settle down to 1.2V, so it would be
>possible for Vbat to be 5.6V initially.
>
>Under those conditions, Rs should be equal to:
>
> VBAT(max) - Vf(min) 5.6V - 3.5V
> Rs = --------------------- = ------------- = 105 ohms
> If 0.02A
>
>100 ohms is a standard 5% value and would force the initial current,
>under worst case conditions, through the LED to be:
>
>
> VBAT(max) - Vf(min) 5.6V - 3.5V
> If = --------------------- = ------------- = 0.021 amperes
> Rs 100R
>
>
>which would be fine, and the resistor would dissipate:
>
>
> P = EI
>
> =(VBAT(max) - Vf(min)) * If = 2.1V * 0.021A = 44 milliwatts
>
>
>A standard 100 ohm +/- 5% 1/4 watt carbon film resistor would be fine.
>
>More later on today...
---
The next thing to consider is how many LEDs you want to use and how
you want to drive them.
Instead of using discretes to build a linear constant-current
regulator (and wasting battery power (and probably money) in the
process) I suggest you go the route of an integrated LED driver such
as:
http://focus.ti.com/lit/ds/symlink/tps61061.pdf
or
http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1094,P37356,D24889
Either will allow you to drive the number of LEDs you need, and
driving 4 LEDs at about 80% efficiency means that the LEDs will be
dissipating:
P = IE = If * Vf = 0.02A * (4 * 3.5V) = 0.280 watts.
If you chose to use three 1500mAh NiMH cells that'll give you:
W = 3.6V * 1.5AH = 5.4 watt-hours
available to drive the LEDs, but you're going to waste 20% of that in
the driver, so you have left, to drive the LEDs:
W = 0.8 * 5.4WH = 4.32 watt hours,
which means that the LEDs will illuminate for:
4.32WH
T = -------- ~ 15.43 hours
0.28W
until the battery voltage falls to 3V.
I think most NiMh batteries are rated at 0.2C in order to get their
full capacity during discharge, so a 1500mAh battery should be
discharged at 300mA or less in order to get the full 1.5Ah out of the
battery.
Since the 4 LED array is dissipating 0.28 watt and the LED driver is
80% efficient, the battery must supply:
0.28W
P = ------- = 0.35 watts
0.8
into the driver.
Then, since the battery is providing 3.6 volts to the driver, and the
driver is dissipating 0.35 watts, The current into the driver must be:
P 0.35W
I = --- = ------- = 0.0972 amperes = 97.2mA,
E 3.6V
which is well below the battery's 0.2C limit of 300mA.
That means that with 4 LEDs in series and 20mA going through them they
should stay lit for at least 15-3/4 hours until the battery voltage
falls to 3V.
In order to keep from damaging the battery, the battery should be
disconnected from the driver when its (the battery's) voltage falls to
3V.
More on that tomorrow, and also on how to charge the battery properly
from a PV array.
JF
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Author: Kris KriegerDate: 01:16 03-06-08
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John Fields <jfields@austininstruments.com> wrote in
news:2nq844llenim5vb0vmmoc5c43ehnap0fmr@4ax.com:
[...]
>
> ---
> The next thing to consider is how many LEDs you want to use and how
> you want to drive them.
>
> Instead of using discretes to build a linear constant-current
> regulator (and wasting battery power (and probably money) in the
> process) I suggest you go the route of an integrated LED driver such
> as:
>
> http://focus.ti.com/lit/ds/symlink/tps61061.pdf
>
> or
>
> http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1094,P3
> 7356,D24889
I saw some of those on-line while searching LEDs, but to be honest, I don't
understand how to use them. OTOH, given what you describe about the
efficiency, I'll give it a closer look. I saved the two links, thanks, so
I can look for more info.
>
> Either will allow you to drive the number of LEDs you need, and
> driving 4 LEDs at about 80% efficiency means that the LEDs will be
> dissipating:
>
> P = IE = If * Vf = 0.02A * (4 * 3.5V) = 0.280 watts.
>
> If you chose to use three 1500mAh NiMH cells that'll give you:
>
> W = 3.6V * 1.5AH = 5.4 watt-hours
>
> available to drive the LEDs, but you're going to waste 20% of that in
> the driver, so you have left, to drive the LEDs:
>
> W = 0.8 * 5.4WH = 4.32 watt hours,
>
> which means that the LEDs will illuminate for:
>
> 4.32WH
> T = -------- ~ 15.43 hours
> 0.28W
>
> until the battery voltage falls to 3V.
Oh! Ok. I didn't realize that.
>
> I think most NiMh batteries are rated at 0.2C
I didn't know what that means, but did a search and found this page - in
case it'll help someone else, here is the link:
http://www.thomas-distributing.com/maha-educate-batteries.htm
The Info about what "C" means is near the bottom, but the page had a lot fo
otehr info that I didn't know, so IMO at least, it's pretty
useful/informative. And now I know what ".2C" means ;)
I've printed out the rest and will go over the paper copy along with my
other references.
Your explanations are very helpful, Thanks again!
Meanwhile, I'm looking up info on "LED drivers" to get moer information and
a better understanding. This might be of use to other beginners (I'm going
through it slowly):
http://led.linear1.org/what-is-an-led-driver/
> in order to get their
> full capacity during discharge, so a 1500mAh battery should be
> discharged at 300mA or less in order to get the full 1.5Ah out of the
> battery.
>
> Since the 4 LED array is dissipating 0.28 watt and the LED driver is
> 80% efficient, the battery must supply:
>
> 0.28W
> P = ------- = 0.35 watts
> 0.8
>
> into the driver.
>
> Then, since the battery is providing 3.6 volts to the driver, and the
> driver is dissipating 0.35 watts, The current into the driver must be:
>
> P 0.35W
> I = --- = ------- = 0.0972 amperes = 97.2mA,
> E 3.6V
>
> which is well below the battery's 0.2C limit of 300mA.
>
> That means that with 4 LEDs in series and 20mA going through them they
> should stay lit for at least 15-3/4 hours until the battery voltage
> falls to 3V.
>
> In order to keep from damaging the battery, the battery should be
> disconnected from the driver when its (the battery's) voltage falls to
> 3V.
>
> More on that tomorrow, and also on how to charge the battery properly
> from a PV array.
>
> JF
>
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