Battery-less LED flashlight

[SonicalFlair127]

Another question

sweet, thanks for the info.

i went out to try to find some enamel wire, but no stores carry them. All they have is rubber insulated wire. The guy at home depot told me to strip the wire and use some gloss finish ( used for wood ) and make my own. Would this work? even if i did 2 coats?

 

[SonicalFlair127]

instead of a capacitor, would i be able to charge up this small battery?

**broken link removed**

i think it'll be easier than finding a huge cap capacitor.. not sure though

 

[Nostrafus]

Sorry for the delay in the first reply.

Okay, you can get enamel coated solid copper wire (Not the kind with braids) from radio shack https://www.radioshack.com/product....name=CTLG_011_010_004_000&product_id=278-1345, that's where I purchase all of mine, and it's less than $5 for 3 spools, for a total of 315 feet/96 meters of wire. You can use the smallest (Red, 30ga.)

And the guy at home depot, yes it could work, so long as you got solid copper wire, if it's braided, the braids will affect the electromagnet, because it's not a solid coil, with a stable direction.

Also any rechargeable battery will work, just make sure your metal wire that you strip the enamel from isn't contacting any of the case (if you've decided to use a metal case), or you'll get more power leakage than normal since it the electricity travels through more metal than normal (the coils).

 

[skiller]

anyone know how or where can I found a site with about how to make a led torch like in eletronics classes
how they teach you how it works, how to make it, a diagram and stuff...
I am doing an assignment on it and I have to research it but I can't found anything after hours and hours of work
only thing is the price and stuff i found... nothing good enough....
pls help!

 

[skiller]

anyone know how or where can I found a site with about how to make a led torch like in eletronics classes
how they teach you how it works, how to make it, a diagram and stuff...
I am doing an assignment on it and I have to research it but I can't found anything after hours and hours of work
only thing is the price and stuff i found... nothing good enough....
pls help!

 

[tansis]

**broken link removed**
Is a good place to start the site is dedicated to led flashlights
use site search with the word "circuit" ----->
**broken link removed**


**broken link removed**
http://www.solorb.com/elect/solarcirc/solarfl

www.elektor-electronics.co.uk
in the november 2002 edition, this design is hard to beat.

 

[skiller]

thanks alot man that was alot of help!

I didn't try the word circuit lol
should of done that!

thanks

 

[Manihigh]

Rip a stepping motor out of a VCR for a rotating crank/jenny. If you want to go for the crank idea. Better than shaking I must agree. There are at least a couple of schematics floating aroung the net that use this method to power a 'batteryless' incandescent torch. If they'll light a bulb then they'll light a LED ( unless it is a very low power microincandescent of course.!)

Salvage man--> SAVE THE EARTH FROM TOXIC TECHNO WASTE

 

[skiller]

It's okey, I already done the project using recycle stuff... hahaha which was my best idea I ever had. and some suggestions made by friend which made it cool

 

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[ziggy53]

Battery and capacitor LED flashlight.

Similar to this discussion, I would like to build a high-power LED light for a Boy Scout trailer. We have tried battery powered lights, but somebody always leaves it on and discharges the batteries.

I would like to charge a capacitor with a battery using a momentary contact switch. When the switch is open, all the power would come from the capacitor. When the cap is fully discharged, the light goes off automatically.

I can get a 10 farad, 16V cap for $2.50, and I think the rest of the circuit would be the same as an LED light.

Ideas? Warnings? Problems?

Thanks,

ziggy53

 

[williB]

Re: Battery and capacitor LED flashlight.

Similar to this discussion, I would like to build a high-power LED light for a Boy Scout trailer. We have tried battery powered lights, but somebody always leaves it on and discharges the batteries.

I would like to charge a capacitor with a battery using a momentary contact switch. When the switch is open, all the power would come from the capacitor. When the cap is fully discharged, the light goes off automatically.

I can get a 10 farad, 16V cap for $2.50, and I think the rest of the circuit would be the same as an LED light.

Ideas? Warnings? Problems?

Thanks,

ziggy53

10 farads ??
i think you must be missing a decimal point somewhere..

 

[Dr.EM]

This might sound loony, but this is what I thought. A 100v capacitor rated at 470mf is easy to come by, at a fair price, and is compact. As someone mentioned earlier, a high voltage cap is more size to power effective. I'm thinking, say 6 of these connected in parralel, charged to 100v then powering the LED through big resistors, well, it'd last a long time, and even with leakage currents, it'd stay charged for weeks, right?
Don't know how exactly to safely charge it, and of course, it would contain a potentially fatal amount of energy, but with care it would make a useful torch in that it wouldn't leak, no battery changing, quick charging time etc.

 

[JohnBrown]

Dr. EM wrote:

powering the LED through big resistors

Big resistors will waste all that power as heat.

 

[Nigel Goodwin]

As someone mentioned earlier, a high voltage cap is more size to power effective. I'm thinking, say 6 of these connected in parralel, charged to 100v then powering the LED through big resistors, well, it'd last a long time, and even with leakage currents, it'd stay charged for weeks, right?

As already mentioned, feeding 100V to LED's is wasting almost all the stored energy - assuming the LED drop is 3V, you're wasting 97% - hardly efficient.

Also, 6 of these would only give you 2820uF - not a very impressive storage facility!. Plus electrolytics are generally leaky devices, they probably would self discharge reasonable quickly.

As the original suggestion was for using a 'super capacitor', that seems a far better bet - they are designed for this very purpose, providing standby power for low current applications. The 10,000,000uF suggested makes your 2820uF look rather sick :lol:

 

[ziggy53]

Re: Battery and capacitor LED flashlight.

10 farads ??
i think you must be missing a decimal point somewhere..

You are so right. I saw 10,000 uF and thought that was 10 Farad. I was only off by a factor of 1000?

Is there any problem with charging the cap directly from a battery bank? Should I limit the charging current?

I've had an electrolytic power cap (ripple) go off/blow up in a computer power supply when I was about two feet away from the open case and that's a real waker-upper. I don't want that to happen to a Boy Scout.

Should I really consider just a regular battery power supply and just put a 555 timer in the regulator circuit to shut down after so many cycles?

Thanks,

ziggy53

 

[audioguru]

Of course you can get a 10 Farad supercap. They are rather expensive and need a fairly low charging current. Let's calculate how long it will power a 350mA Lumiled:
1) Charge the cap to 12V. Use a 27 ohm/10W or 15W resistor to limit the LED current to 315mA.
2) The LED will continue dimming until the supercap's voltage drops to 3.5V. So an RC of 27 times 10 is 270 seconds.

The dimming of the LED would be a big problem, but at least gives a warning. You could replace the LED's current limiting resistor with a current source, then the LED's brightness would remain high until it quickly fails at the end.

 

[ziggy53]

AudioGuru,

That's a pretty compelling reason to use a conventional battery source.

OK, I'm off to build a timed power supply, with a momentary contact switch and latching circuit until the timer says, "off". A little more complicated than I was hoping. I don't suppose such a circuit already exists?

Thanks,

ziggy53

Of course you can get a 10 Farad supercap. They are rather expensive and need a fairly low charging current. Let's calculate how long it will power a 350mA Lumiled:
1) Charge the cap to 12V. Use a 27 ohm/10W or 15W resistor to limit the LED current to 315mA.
2) The LED will continue dimming until the supercap's voltage drops to 3.5V. So an RC of 27 times 10 is 270 seconds.

The dimming of the LED would be a big problem, but at least gives a warning. You could replace the LED's current limiting resistor with a current source, then the LED's brightness would remain high until it quickly fails at the end.

 

[northernflame]

Hi.

I agree that your will need a some form of rechargable battery in the circuit
design.

Now. There are already several shakelites out there that have a new design in thier circuitry.

Some have two coin type rechargable lithium batteries (simular to the coin batteries used in computers but rechargable.

The difference in the new shakelite (battery type) is the capacitors.

Some have a full size capacitor (varying uf), and others have a cheap variating capacitors. from what i could read through the semi clear plastic of the larger flashlight the capacitor looks like a 50uf 10v. However i could be wrong , it's hard to read.

The smaller capacitor type does not have the ability to drive the led bulb all that well and tends to drive the light spectrum more to the blue end.

The full size capacitor version of the shake light (the flashlight is a bit larger) has a much brighter beam, and last litteraly for hours on end even with a 1 min shaking.

Lithium cells do not over time drain all that much.

The only claim i can not make is the 10mm LED you mentioned. most of the shakelites use either 3 or 5 mm led's also the shakelites use a magnifying glass like lens to focus the led's beam. For the larger and brighter shakelight it's ok, however for the cheaper shakelite it realy makes a mess of the beam.

Normaly i build led flashlights that use rechargable AAA, AA, C and D cell

I would also be interested in the performance ratings of a real full size capacitor shakelight with a 10mm led.


Thanks

 

[justDIY]

I don't know if you found a source for supercaps yet, or if you're still looking, but I ran across some at MPJA (flordia, usa)

https://www.mpja.com/directview.asp?product=15990+CR

perhaps an array of those 2x2 (series and parallel) to get a respectable voltage and then drive an led array (say 3x 3v white leds)