Battery-free flash light

[5614]

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.

[YT2095]

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.

[5614]

the 1F was £80, thats loads, what can someone do with it?

[Guest shalesh]

tellme from 1st that it has a very common part.

[YT2095]

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

[Lance]

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.

[boris_73]

im sorry to say but one has all ready been built you wind it up like the wind up radio i think it was a british inventor who made it

[Lance]

I'm not trying to invent anything. It was just a normal project like any other.

 

http://www.thinkgeek.com/gadgets/lights/5a9f/

[5614]

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]

[Lance]

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.

[5614]

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.

[YT2095]

DON`T use a resistor, you want to maximise the little amount of power you have, not waste it!

[5614]

thats what i said in post #10 but:

 

A LED is simply a diode. Without the resistor the cap would completely discharge through the LED in a fraction of a second

(in post #11)

[YT2095]

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.

[5614]

.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?

[YT2095]

it`s the "turn on" point for Silicon based semi conductors with Typical PN junctions. that includes LEDs.

 

but there are levels of hysterisis whereby the "switch off" point may be below the .7v

[Lance]

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...

[YT2095]

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

[MolecularMan14]

http://www.kopes.com/affiliates/egadgets/magnet-magic-battery-free-flashlight.htm

[YT2095]

I`ll bet it makes the Myopic neigbors talk about you while you`re shaking it though! )

[psi20]

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

[psi20]

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.

[YT2095]

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).

[Lance]

Radio shack sells nice spools of magnet wire. It comes in a bag with three different gauges. Red green and orange enamel I think.

[psi20]

Alright, thanks.

Why's the tube containing the magnet have to be plastic, an insulator?

And Lance, how long did it take to wind the coils? Did you have to tape the coil to the pen tube to make it stay on?