Is that for rectified AC or DC conditions? I tried to simulate this thing but I don't know how to convert a complex rectified waveform to a RMS value. I tested a 120V 100W bulb today on DC and got 350mA at 22 volts DC (63 ohms) and the bulb was just glowing orange.So, using 8 batteries in series (120V system) would put about 24 volts across the bulb for a charge current of
380mA. Using just one battery, the bulb would get almost the full voltage and the current would be about 1 amp, and so the current varies by 3X while the number of batteries varies 8X and the worst case condition is when most all the voltage is across the bulb, which is normal operation for the bulb and it never burns out. But that's for DC conditions. If the input is full wave rectified with several batteries in series, the conduction angle is only a few degrees before anything happens, so it's hard to calculate the RMS current when the diodes conduct for only a short time during the cycle. .
I bought one of those 60 watt LED bulbs at WalMart today for $2.44 and it runs very cool at 8.5 watts real power. But it generates RFI, so I had to move the table lamp farther away from the radio.
BTW: I got a 10 dollar tip for playing piano at Cypress a few weeks ago. I tried to talk her down to 1 dollar, but she refused. .
1.4 billion users at $10 a pop is $14 billion. Distribution costs would mak e it more. No agency, business, charity or government anywhere in the world has that kind of money to spend on tiny 10mW lights. And that's only for a little light, people have a whole lot of other needs. Ie it isn't going to happen, any time in my life at least. If you're trying to solve poverty th at's a duck with 2 legs, 2 wings and a beak missing.
so it can act as fuse as well
3v LED at 10mW = 3.33mA. We need resistance to limit LED current, wire re sistance is well under that. There is no issue.
I don't like 10/0.1, but where it's all fixed & out of reach it will do. En d users can use any wire they please, even 1/0.1. I'm not worrying over a n onissue.
We've spent plenty of time living with the prospective end users. Some of t he main issues are food, clean water, clothing, shoes, education, access to basic justice, medical care, income making opportunities etc. We have othe r nonelectronic projects for some of the other issues. I ask here mainly wh en I'm scratching my head on the electronics.
Electronics is a bit different in that no other organisation is offering el ectronics courses & projects afaik. It also offers a way completely out of poverty for an unknown percentage, and can make a real difference to life i n some respects for most, eg with lighting, sterilisation, security etc. It also enables some to produce & sell useful goods for income.
Radio isn't top of my priority list at the moment, but it will happen. When it is I'm not going to worry too much about listener demographics.
I think you've misunderstood where I'm at completely.
As I explained it only takes less than 1% of people to produce the goods fo r their use to spread. There's a great deal more interest in practical skil ls over there for obvious reasons.
I'm not making sense of that.
es.
obviously
Sure. But they still survive, and only a percentage will have cell life sho rtened.
I've studied garbage for a long old time. I guess you've no idea how dump c ontent varies in different areas.
Yes, I thought I mentioned that. Why don't you email me
Perhaps it would surprise you to know that a perceptage of people appreciat e what they have and take care of it. One can design robust, but no electro nic appliance is bulletproof and we must all accept that.
electronics courses & projects afaik. It also offers a way completely out of
poverty for an unknown percentage, and can make a real difference to
life in some respects for most, eg with lighting, sterilisation,
If you want to save the world, sterilization is the key. Widespread sterilization, even in the first world, would solve most of the world's problems in a generation.
security etc. It also enables some to produce & sell useful goods for income.
Correct. Now try a different exercise. Calculate what it would cost YOU to ship an empty box. That's a product that has a zero dollar cost to sales, but still requires all the usual overhead of packaging, documentation, shipping, handling, procurement, testing, compliance, certification, rent, promotion, CEO/CFO/etc bonus's, bribes to government officials, and all the other expenses NOT directly involved in building the product. It's a very handy way of determining the minimum selling price of a product. For example, if you sell the device for the cost of shipping an empty box, you're giving it away at cost. I actually did that exercise for several companies where I worked in a futile effort to introduce some sanity in their pricing policies and procedures. I failed and somewhat later, so did they. In about 1997, it cost one domestic consumer electronics company $75 to ship an empty box which should give you a clue as to the approximate cost.
You're asking the wrong question. The right question is "why don't they have domestic electric power"? If you want to solve more problems than light suitable for reading, you'll need real electric power. Part of the answer is copper theft, lack of clear title to the house, and general lack of all municipal services. There are others. Fix those situations and you might have something worthwhile.
It's good to say something positive about everything, but there are some areas where such positive thinking overlaps a design failure. You're there now.
Ok, so you have some field experience. That's good.
Most 3rd world countries have extremely high unemployment rates. The assumption is that those seeking jobs are qualified to do the work, which means that they already have some training or education. Electronic courses and projects may help, but methinks education in areas with no available jobs is not going to have a big impact.
You might want to ask a 3rd world electronics dealer what is selling and where is the demand. AM, FM, broadcast TV, DBS, cable TV, etc.
Probably true. I have to do quite a bit of guessing as to what you're trying to accomplish, what you have to work with, and what problem are you actually trying to solve.
So, the production skills of 1 person is supporting 100 unskilled people? That doesn't sound right.
You suggested that they use whatever batteries are available. I contend that they're likely to obtain used batteries. You suggested that using over-capacity battery banks would eliminate the need for a charge controller. I contend that this will result in battery failures, leaks, and equipment damage. If you build using junk parts, you're likely to end up with more junk.
An overheated battery does NOT survive. I have the scorch marks on my Formica workbench and home computah table to demonstrate the results. "Charging nickel-based batteries at high temperatures lowers oxygen generation, which reduces charge acceptance. Heat fools the charger into thinking that the battery is fully charged
Notice in Table 1, the range of acceptable charging temperatures. If you overheat the battery, you are probably exceeding the recommended maximum cell temperature.
True, but my experience doesn't matter. It's yours that's important. Hopefully, you're not suggesting that your product be built from components salvaged from the local dump. My comments were about the condition of the electronics found in the dump, which is an indication of how their former owners treated the electronics and what you should expect for your fast charger.
I didn't see anything on the topic. I just reviewed all your posting in this thread and didn't find anything. Article number?
I'll gladly send you email if that's what's necessary to obtain your model, but please note that with email, only the participants learn anything new, while posting the same in a public newsgroup or forum allows everyone to learn and comment.
It would. The problem is that I don't see them. I'm in the repair business and I only see the broken machines. I'm sure there are people out there that are conscientious and careful with their electronics, but from my perspective, they are the exception. The problem is not that some people intentionally damage equipment. It's that they do not have the early childhood education in handling tools, equipment, or electronics properly. We tend to assume that any survivor of the American education system is able to operate, for example, a screwdriver. Yet, I've seen people that literally cannot do so, and have extreme difficulty learning to do so later in life. Handling electronics is part of that. I have a friend who learned to type on a mechanical typewriter. 30 years later, he destroys one computer keyboard per month by punching the keys with the same force as if it were an old style mechanical typewriter. He knows about the problem, knows that it's not a good idea, has tried to learn to type lightly, and utterly failed. I've seen similar problems with other keyboards, controls, and devices. The percentage of people that appreciate what they have, and TRY to take care of it is probably quite high. The percentage of those that succeed is much less.
I assure you that the product liability legal establishment will not accept any form of failure. Even devices that are inherently dangerous come with safety features intended to protect the user from injury, and the manufacturer from litigation. Knowingly admitting to and perpetuating a hazardous product is not considered a good idea in most courts. Claiming that nothing is foolproof is not a usable defense.
Ugh, 1AM. Time to give up. Good luck (again) with your project.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
cial products which rules them all out. $10 a light for 1.4 billion people, do the math and you see why. And that's just for a low power light. The pr omotional blurb for the book, the less said the better.
reliability or a metre or 2 of 10/0.1 I can't imagine too many stealing. L ess than a foot will be external anyway.
Or don't use any wire at all. The unit's more versatile if it can be moved to be used as a flashlight, as a room light, reading light, etc. anyhow.
Radio and light -- interesting idea. Those may be very helpful. When prop erty is not safe, when public officials commit injustice rather than assure just ice, when the laws take from some and give to others, this is what keeps people poor.
How does a society bootstrap & break out of that cycle? Doing so has been the rare exception in world history; despotism, lawlessness, and poverty is the rule--examples are everywhere, e.g. Mexico.
America broke out by a unique history--distant colonies of necessity creati ng self-rule, long experience at that, then uniting, intentionally, under a thoughtfully innovative, agreed plan secured by a written document.
France's attempt at following led to three generations of bloodbaths, coups , dictators, emperors, and civil war. So, freedom is not for the inexperienc ed or for the faint of heart.
Not sure, but letting people read and hear about their own, and other societies' examples, this seems useful, peaceful, maybe even enabling.
oing payments. Any time you bring that kind of model in the cost goes up, u p and up, because suddenly you're also paying for someone's business & prof it.
I like the idea of *all* models being possible, including payments. Let th e people experiment and decide what works for them. Different individuals wi ll prefer different methods, models, prices, and payments.
r batteries they can get. In most cases that's going to be ones with far mo re capacity than is essential, since those are the cheapest locally availab le options. The upside is we can abandon any form of charge control, it's n o longer needed. Thus unit cost drops, not increases.
to check battery temp while they charge & stop if it heats up.
I really don't understand Jeff's worry about EoC and overcharge. One minut e of 4C isn't going to heat anything very much, especially if you're putting
A fixture wastes too much light, something poor people can't afford. For micro-power super-cheap lights to be useful they have to be directional, concentrating the light to where it's needed.
Check out this absurdly wasteful illustration of an earlier effort--
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The light is blasting most of its output at the ceiling, walls, and into the poor little girl's face. Shining directly on the book would yield better illumination and better reading conditions with a tiny fraction of the power requirement. Lower power means cheaper, smaller, less solar panel, etc., by a factor of ten or better.
(main article...
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I strongly agree with you. Even very poor people living on $2/a day can pony up a day or two's wages for something they truly want and value. And doing so means they're invested in the thing they bought, and encourages sellers and makers to bring new products to market.
Yep, you're dead-right, and that approach quickly turns whatever's handed out into trash (ready for NT's recycling ;-).
From the article I linked, "In Ethiopia, [...] the World Bank, the Government of Ethiopia and Lighting Africa established a US$20 million financing facility for off-grid solutions. Within 18 months, the scheme enabled more than 300,000 quality-verified solar lighting products to be imported, providing one million Ethiopians with access to electric light."
$20 million for 300,000 lights works out to $66 a light! Genius!
Right, except government-funded projects have to pay their bills too. All that money has to eventually come from (and be repaid by) the people being 'helped.' And in poor, corrupt nations, the rulers aren't interested in anything that doesn't personally benefit themselves.
The solution to poverty *has* to come from the people themselves, organizing themselves into a functional civil society. Air-dropping fish simply won't ever do it. Businesses will never form if they're looted by officials, or can't depend on stable, enforceable contracts, laws, and conditions long enough to justify their risk-taking and investments.
Bill's an outstanding ragtime / stride / boogie-woogie piano player--he's cookin' with gas. Known for random acts of public performance. Great to listen to.
What it costs us to ship an empty box has little to do with minimum sale co sts in the developing world. Every component of the 2 is quite different. D ead lightbulbs are perhaps a fair indication of their minimum product price , about 2.5 US cents.
Take a typical developing country example we saw:
You can if you want. I'm more into things that have a chance of working
:) Only if you take my comment and extrapolate incorrectly.
Where in the world are there zero jobs? Where in the world do you have to g et a job to make income? The point is just not valid.
Folks buying those things are not the people I'm aiming at.
1 person produces goods for many unskilled customers, in this case lighting
no
when they're available and usable yes.
Chucked out batteries fail, that's not news. Crude charging produces more f ailures, that's not news. Equipment damage from leaks is trivial in this ca se, it's designed to be.
Hmm, it worked for me for many years. Electronics is one of those areas whe re a huge amount of good usable material is lying around for the taking, ev en in the developing world. That's one of its attractions for over there.
shortened.
How long at how many C got you scorched? Limiting i with a resistor is chea p & simple.
Short charges require oversize cells to get enough charge in. If you don't like that approach, you're only left with 3 other options:
Let them crank away for 14 hours each day
Put an unaffordable controller in so they can crank for 30 minutes a day
Use a grossly unaffordable supercap so no-one ever builds or uses the pr oduct. I say no to those
Of course I am. Where else do you get components when you have no money? Th ere's masses of good parts dumped in much of the world. It's a valuable eas ily mined vein of resources, there free for the using in lots of places.
In any large number of people you get all sorts. Over here people too often don't respect products partly because their benefits are largely trivial, and can pretty much be taken for granted. When your little light enables yo ur kids to learn to read or avoid the risk of being horribly burned it's a different story.
you lost me
As a repairer you see a filtered subset of people
maybe your legal system is different. Here you need 2 layers of safety agai nst injury. 2 is enough.
some do, some don't, some are required, some aren't.
It's not hard to have enough resistance to keep the current below potential injury levels. Calm down lad.
As a point of debate only, companies do what you describe widely here. They 're called cars, power tools, sewing machines, shears, hedgetrimmers, sciss ors, knives, sporting goods, light bulbs, carpets, electrical systems, fire places, houses, the list of things that can be made safer but aren't goes o n & on.
it wasn't offered as a legal defence against liability. It's a simple state ment of reality. If you're criticising obvious facts, something's gone adri ft.
The very poor live on 8p a day, about 12 cents. $2 is well above the range I'm looking to cater for.
Partly it needs to come from outside, from those of us with the luxury of being able to spend the time working out what technologies can actually work for these people. They're too busy working to trawl the net & experiment.
Functionality comes first in the third world. Anything else is added initial cost and added running costs to no good end.
Depends on the fixture. One of the simplest is some aluminised pie tray plastic and an LED on 1mm single core twisted together so it can light a clip board which carries the batteries on the reverse. Task lighting to allow a child to read and do homework being one route out of poverty.
Designed by marketing men implemented by bozos.
I think you have to get the build cost well down and simplify.
But for 3mA or even 10mA LED lamp then three primary cells and a modest resistor are the minimalist solution. Multiple taps to allow semi dead discarded batteries to be used would be the other solution.
I think the least bad option is more along the lines of how things were done in the UK prior to the national grid. Basically have a few guys with battery chargers who service a load of other folk with rechargable batteries. The charger can then be optimised rather than minimalist.
Exploit the intrinsic voltage drop of the LED and primitive 12v SLA as the power source - they are more robust and likely to survive in the field and will drive 3 white LEDs in series with a diode and a current limiting resistor for a very long time. Choice of resistor optional to provide task lighting or night light functionality.
The battery self discharge is broadly comparable with 10uA which is more than enough to make the LED provide light in the pitch dark for the dark adapted eye.
It tends to line the pockets of corrupt politicians without ever being turned into actual products. Look how much "reconstruction" money the US sank into Iraq with essentially nothing to show for it...
Depends how good they are. As a calibration point in the first world you
which translated to $7-10 depending on how you do the exchange rate.
Cellular is there already various phones in the $10 range exist and imports of usable discarded handsets from the first world are common.
They may be out of reach of your target market but they are there.
oh yes. Nothing is done that doesn't need to be, or doesn't profit them.
r
,
I like that idea. If we lost the pie dish & scraped the LED rough, the ligh t distribution over a page might be ok. I'll have to try it.
1mm wires would snap after so many bends. Flex wouldn't hold the LED in pla ce. Some solution needed.
pony
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I'm liking that too
Mind you, taps means the LED would be overcurrented by people seeking more light, and die an early death. A switched mode circuit would handle all tha t automatically, but is more cost & much more skill requirement. Maybe ther e's a place for both.
That brings a lot of labour cost, but maybe. How does the energy distributo r get their electricity?
Yes, except that SLAs are way unaffordable. It'll need to be NiMH. I don't see a way to make reuse of discarded Li cellphone batteries safe.
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all designed to die soon. It still doesn't cost $66 to produce something re liable.
Cellphone service, internet etc has its uses but just doesn't tick the boxe s. I'm looking for technologies that serve a useful purpose, provide the pe ople involved a means to make money, can be made with roadside junk, are af fordable to a substantial percentage of those in poverty, and use parts & c ircuitry that's likely to still be doable in 50 years time.
The LED itself has sufficient directivity. Thirty degrees might be nicer t han the more-common standard 20 degree units, but either is fine.
For fixture, I'd suggest a headlight. That points the light wherever the user looks. Or hang it on a string from the ceiling, 50-100cm over the stu dy table.
These people have some flaws, are too pricey, but have some creative usage ideas--
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pony
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Solar garden lights are already under a dollar, retail. That's pretty attractive.
But, a secondary NiMH 'AA' costs only double what three 'AA' primary cells cost, yet has >200x the useful illumination lifespan. IOW, it's much cheap er.
If you over-size the cell and only run it to, e.g., 10% depth-of-discharge, a single NiMH cell can give many years of service.
I like and suggested that model too. A 10mW light could be personal and so lar- charged. A more powerful light--a different product--could use different storage, cost more, and be charged by a passing car, or some budding entrepreneur with a large solar panel, bike-generator or windmill, as a for-pay service.
ed out
Yes. It gets to my premise that, at bottom, the people themselves have to create a functional civil society. Unless property and investment and gains are protected, no one will bother trying. It wouldn't make sense to.
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10mW-range solar-charged garden lights are sold for roughly a dollar, retai l. That could potentially benefit roughly 66 times as many people on the same budget as the $66 lights. (In fact many, many more , since disproportionately more people can afford a $1 device compared vs. a $66 device.)
I couldn't find the creative ideas. They do units at high prices, but also ones down to $4.30 if you buy 60 - but no specs. I daresay they're seriously low end, probably much like garden lights repackaged.
Yes. I can see theft being a real problem with them.
exactly, there are some good upsides. Whatever the DOD, 10x the capacity means 1/10th the cycles. And AA & AAA NiMH are the most available types.
The flipside is that often poor people can only set up home in areas where no such protections exist.
Later I'll look at more powerful options, 10mW isn't quite the ultimate light after all. But first something cheap.
An article about harvesting the circuit (as a Joule Thief):
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And you can buy 100 pieces for $9 with free US shipping:
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When Microchip first introduced their nanopower PICs, they showed a circuit running on a "grapefruit battery", but it didn't have quite enough voltage to work reliably, so it took two grapefruits. That's another idea for a power source, especially in tropical areas, but it may be a waste of edible fruit, and the fruit may not be safe to eat after using it as a battery, depending on the metal used as electrodes.
The grapefruit battery was also used to demonstrate the TI MSP430:
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Or you can use potatoes and copper/zinc electrodes for about 0.8 V/cell:
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That driver IC solves the problem of overdriving the LED and also gives much better efficiency than a dropping resistor. The inductor is probably not critical and could be made from some re-used transformer wire wrapped around a chunk of iron, or ferrite from an old computer PSU, which may also be a good source of other components to re-use. Labor intensive to remove, clean up, and test components, but might be a good job to do so and then sell the components.
o The light has a ring stand that stores inside the lens. o There's a hanger / stand - with a plastic adapter that screws into an Edison socket, for support - the stand permits aiming the light for use, and for charging - hanger also allows hangs from string, nails, or branches o Two brightnesses, and auto-off in daytime. o Water resistant o tough ABS case
AFAICT they full-cycle the NiMH daily, limiting life to ~1.5yrs, give or take.
The IC is a nice option - I'm tempted to look at modding a garden light to improve its performance. The rest is already there. I know in principle I c ould design a new light using the 5252, but it's a lot of technical complic ation plus a part they probably won't be able to get.
For something simpler, longer running, more power options and similar price I like the idea of spending more on the cells, and can then cut right back on the electronics. A resistor is then plenty, 1 for charge control, 1 for the LED.
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