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Battery-free flash light


Lance

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its 20 - 24V DC actually. i just checked, sold in maplins, i can tell you the exact address, but go to http://www.maplin.co.uk/ search 'capacitor' and near-ish the top there 1farad capcitor, click that, then go the FAQ for V rating.

 

it says it: Improves crispness of bass

and is:

For demanding in-car systems

 

is there anything which i could use this for?

 

oh, yeah, it cost £80 [uk money] and thats a lot.

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big enough? i once saw a 1F capacitor, but i couldnt think what do use if for.... what can you use massive things like that for?

I had several 3.5f caps, it`s no big deal, you may as well use Ni-Cads!

Yeah, I was disappointed too :((

 

they used them as backup power for the BIOS in a few old PC makes. 5 volt rating.

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  • 3 weeks later...

Lance I`ve been thinking about this project of yours, the tube, I hope it`s plastic and not any type of metal, also as well as having a spring at each end, make sure the ends are open enough to allow the air either side of the magnet escape easily.

 

that`s it so far :)

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Lance I`ve been thinking about this project of yours' date=' the tube, I hope it`s plastic and not any type of metal, also as well as having a spring at each end, make sure the ends are open enough to allow the air either side of the magnet escape easily.

 

that`s it so far :)[/quote']

 

Well thanks for the thought! The tube is plastic but there are no holes in the ends. Ill drill some holes in them and see how it works out.

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how does this work?

like is the loops [around the magnet] connected in parallel with the capacitor?

wont you need a polarised capacitor or a diode, because the shaking effect would create an AC current.

and then is the LED connected in parallel to the capacitor?

what rating is the capacitor? [in decent ones, such as the one linked in the above post]

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how does this work?

like is the loops [around the magnet] connected in parallel with the capacitor?

wont you need a polarised capacitor or a diode' date=' because the shaking effect would create an AC current.

and then is the LED connected in parallel to the capacitor?

what rating is the capacitor? [in decent ones, such as the one linked in the above post']

 

I posted a schematic I drew in post #1. The cap is charged through a bridge rectifier.

 

I have no idea what the rating is on the think geek light because buying it would detract from the point of building it.

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ooohhhhh yeah. omg soz, i forgot it was this post with the drawing... oops! i wasnt expecting you to know, but are we talking just a 100uf cap or some mega 3.5f cap?

pressumably you only want a small resistor, to protect the LED, but no much else, you could buy a hyperbright LED, to make a low powered torch.

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it shouldn`t, it`ll charge to .7 of a volt before any use of it comes into play. and if the charger cct isn`t sufficient, using a resistor won`t help much either.

it should be able to work without the cap, the cap`s there only as a buffer/reservoir between magnet slides.

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.7V is the turn on point of a transistor, does it apply to a cap as well????

does anyone know the kinda voltage that the 'shaking' will produce. as in, if you shook it violently, it could produce a high voltage and damage the LED, we made assumption that it wouldnt be too powerful, but a lot of winds, powerful magnet, lots of shaking, who knows?

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Well, I drew the schematic before I tested it. If I had known that the power output would be so low I would not have included the cap or the resistor. I probably dont even need the bridge. I dont think I need to worry about high voltage...

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you can Halve the bridge losses though :)))

 

atm, you`re losing 1.4 volts with a fullwave rectifier. why not center tap your coil, use that as - and then ony 2 diodes (one off each coil end) to make a full wave :)

that way you`re not losing as much :)

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  • 3 months later...

I read the thread and now I want to make one too. Hey YT, why does the tube need to be plastic?

I researched about this and got some info.

One volt is produced when 100,000,000 "lines of force" per second are cut by the wire.

Stronger magnet = more voltage

faster motion = more voltage

more coil turns = more voltage

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I'm new to engineering stuff. Where did you get the coils from? I have something from Radioshack called a "Rosin Core Solder." Is that what you use? There's a warning on it for cancer and stuff. It sounds pretty dangerous and I don't want to use it if that's not even the right stuff to use.

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solder`s no good for 2 reasons, 1 it`s not insulated. 2 it`s a poor conductor.

 

the typical coil material is enamelled Copper wire, sometimes called Magnet wire (as seen in the windings of a transformer).

 

often red/orange color and sometimes Green or Blue (but those colors are mostly seen in small toy DC motors).

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