Flashlight Without Batteries--from the book, "Haywired"

In this project, you will make a flashlight that works without batteries. Even more amazing, you can recharge it in three minutes and it will run for more than 24 hours. Because the ultra capacitors can be recharged thousands of times, you may save the environment from ever receiving an old flashlight in the trash system.

This project is from my book Haywired

Click here to order a copy from the Chicago Review Press.

Parts List

(2) 220 farad capacitors, www.digikey.com, #589-1013-nd
Insulated wire, black and red
Solder
LED, high brightness, www.jameco.com, #217525
12" x 12" acrylic plastic sheet, 1/8" thick
Permanent marker
(2) C clamps
Epoxy
1/4" jack, Radio Shack, #374-280
Metallic tape
SPST rocker switch, Radio Shack, #275-693
Glue
Electrical Tape

Tools List

Wire cutters
Soldering Iron
Scoring knife (for plastic)
Single-hole paper punch
3-volt DC power supply--700 milliamp
Drill
1/4", 1/16", and 3/4" drill bits
Metal straightedge

Step 1: Put capacitors in series

First, solder a wire from the (+) on one capacitor to the (-) on the other capacitor.

Comments

[Schmidty16]

how long does it last

[MikeTheMaker]

It's good for an hour or so at reasonable brightness--but it will continue to produce light for 24 hours or more.

[Schmidty16]

cool man i like

[viswamtvs]

i tried it
very nice

[luxstar]

done.. Here is the link to the 2600 farad flashlight instructable:

http://www.instructables.com/id/2600-Farad-Capacitor-Flashlight/

[MikeTheMaker]

Anyone interested in supercapacitor projects should look at this--and follow the links to suppliers. Luxstar has pointed out the best price for big caps that I have heard of!

[luxstar]

I recently made a supercapacitor flashlight that requires no batteries. I charge it off of a 5 watt solar panel. The larger capacitors of this type are usally quite expensive but the $10.00 2600 farad capacitors are back for now (on home page of Goldmine-Elec plus others on boost cap page).
Here is the link plus the link to instructions, diagrams, and pictures of the flashlight.
http://s247.photobucket.com/albums/gg153/luxstar/
http://www.goldmine-elec.com/

[MikeTheMaker]

Great resource! Thanks for sharing.

[luxstar]

Working on adding the pictures

[BC-45]

How do you charge a capacitor that is rated at 350 farad 2.7 volts any one know cause i don't know is it's safe to charge it wiht a 15 volt power supply.

[D5quar3]

 Digikey stopped selling the ultra capacitors anywhere else I can find them

[EngineeringShock]

www.electroniclessons.com will take you to an ebay store that sells all sorts of them. DC-DC boosters as well.

[Kasaron]

Seems like this needs to be hooked up to an induction generator, to really make it an emergency flashlight.

Anyone know if I have to use an AC/DC rectifier to sort out the charge?

[EngineeringShock]

To charge this circuit using even a good DC crank would take a heck of a long time, and it would result in an extremely sore arm =s

[LazarusTree]

This circuit seems potentially very dangerous to me. I think there needs to be at least one diode between the voltage input and the capacitors to limit electron flow in one direction and with a voltage rating less than the capacitors.

On what you have here, if you reverse the voltage and/or exceed the voltage rating on the caps and this is a potential bomb that will send shards of plastic flying everywhere.

[EngineeringShock]

If his input voltage is 3VDC, then he's not going to over-charge the caps. I'd be more concerned for the input source with no limiting resistors in series with the caps. That's a good way of destroying your wall wart,

[shobanaelango]

Are you suggesting that in any circuits it is better to use a diode between the voltage source and the capacitors? if we should add diodes to prevent from any accidents in a circuit in what all conditions and with what all components should we do that? It would be very kind of you to reply me............

[MikeTheMaker]

If you choose to Use a diode, it should have a higher voltage rating than the capacitors and it should be able to handle as much current as your power supply provides. If you power supply has diodes on the output (and no capacitors beyond the diodes), then you probably don't need an additional diode. Although these capacitors store a lot of energy (for a capacitor), it's less energy than a "aaa" battery.

[BC-45]

So how is run time determined by ferrad like if i have a 100uF cap it will last less and if i use 100F it will last longer is these right?

[MikeTheMaker]

Yes, the larger the amount of farads, the longer it will last.

If you can determine the "ohm equivalent" of your load, then the formula, T=RC where T=time (in seconds), R= resistance in ohms and C=capacitance in farads; then T will be approximately how long your capacitors will supply some power to your load. For example, if your load is 1000 ohms and you are using a 1000 microfarad capacitor (1000 X .001 =1) then the power will last about 1 second. This is the reason that you need capacitors with farads (not microfarads) of capacity to power anything for very long.

[Claudio_MV]

Hi, can I make this work with 2 1000 microfarad 200wv capacitors?

[MikeTheMaker]

The capacitors I suggested (in series) are the equivalent of one hundred ten million microfarads--so your capacitors are about 1/10000 of the storage.

That being said, what you have will work--but only for a few seconds.

[alexanderm]

Great Instructable! Thank you for sharing it!
Hopefully, it inspires people to buy your book!

i couldn't help but to think how cool it would be to add some solar cells in that clear case, though!

[Waren-Neutron]

such a great idea or i called invention
it so easy and educational ha....

[spark light]

(removed by author or community request)

[skyhell2009]

Can i use only a 1F capacitors..??

[MikeTheMaker]

1 F will work for a few seconds--enough to experiment with.

[MikeTheMaker]

The suggested capacitors are 220 farad rather than microfarad.

[skyhell2009]

Why we have to use 2 of 220F capacitor in this circuit, not only use 1 capacitor..???

[spark light]

these capacitors are only rated for 2.5 volts, and the led needs more than that to illuminate.

[MikeTheMaker]

You need to use two in series so that the voltage rating will be higher than the voltage required by the white led.

One capacitor (usually rated around 2.2volts) will be damaged if you charge it to a high enough voltage (around 3.5 volts) to light the led.

[spark light]

Oops, sorry. I misread it. Anyway, the caps have been discontinued, and it is pretty hard to find alternatives.

[shobanaelango]

Thank u very much for your response..... I have been doing a project on the topic RPS. So I made one. The specifications for it is (0-12)V. Since it is of variable type I used a LM317 regulator for it. The problem is I'm getting an output voltage range from (1.4-12)V but i should get from (0-12)V. After browsing thro' the Internet i found that diodes can be used in the circuit for that purpose but still, i don't know where to connect the diodes in the circuit to get the result........ I'm looking forward to your reply...........

[ukcuf]

Am I missing something here or are you effectively halving your capacitance by putting them in series One on its own 220 F Two in parallel 440 F Two in series 110 F (in the instructable they're in series?)

[MikeTheMaker]

I'm going in series to boost the voltage--2.5 volts is not enough to operate a white led (unless you add some circuitry, which is certainly a reasonable--though more complex option). It's actually the same power delivery, because doubling the voltage results in 4 times as much power delivered to a fixed (ohm) load.

[arkho]

I don't think so brother, because this led light consumes very minimal power. You can even light up an old school red led with a 1k resistor without charging it.  On the other hand, laptop as we know consumes more power, given the motor in the hard drive, the fan for the CPU and not to mention the back light for the LCD. Now most laptops, especially the new ones has lithium in the battery where the charge is stored that's how it sustains the need for power. However about the lifespan of the battery, I would say that one year is the normal life span of a laptop battery. I should know, 'cause I work for a computer company. :-)

[nani2010]

hey those are only farad capacitors or micro farad.
i got only micro once plz reply that what i sould keep.

[trekman]

I see finding a 200 to 220 F cap is difficult and expensive. What are any substitutes? I don't know anything about how to figure anything out but there should be trade offs in charging time and how long the LED stays on for different size capacitors. Can anyone give some options? Maybe using 3 or 4 of a easier / cheeper cap to get. Gerat Instructable!

[KT Gadget]

Here is a site that does give out some decent size caps. These I saw from Popular Science used in an electric screwdriver that is charged by a usb. Doesn't do big-heavy projects but it is good for short ones.

Only downside to these is the max voltage going through all of them is 5V in series (so 2 max in series). Putting them in parallel pairs, however, you can probably come close to matching to this instructable.

[scratchr]

use a supercapacitor (http://en.wikipedia.org/wiki/Electric_double-layer_capacitor)

[Articas]

ah excuse me but WTF DO YOU FIND A 220 FARAD CAPACITOR
but yeh this rules no probs with batteries leaking and quick charge time
i wonder if you could add a car adaptor
 

[andy_ram0ne22]

it works with a capacitor of 160uF -- 330V from a old camera?

[AuzzieGuy42]

No it won't. 1. The voltage is too high.. unless you can get 330V to 3.5V~ then it should be suitable. 2. The capacity is too low.

[scratchr]

Actually the voltage is the max the capacitor can handle, not its output.

[AuzzieGuy42]

Oh, my bad. I'm kind of new to this electronics thing.

[٠ح٠ود63]

Beautiful work,

[eyerobot]

Very nice project!
I always enjoy reading new ways to do things, And this is definitely cutting edge.

[Wasagi]

 Excellent Job!

[pandyaketan]

Instead of charging it with a 3V DC power, how do i charge is with 220 V AC Mains ? I am from India and we have 220V here. Maybe others would like to see 110V battery also...

Chinese batteries nowadays have wall mounted charging pins in them..

My question is: what would be the configuration of the capacitors and how many LEDs...

if someone can post a couple of projects.... that would be nice....

reg
ketan

[stephenniall]

Get a 240 vc ac to 3 v dc Wall wart ! down here in uk we have 240 v mains aswell.

OR buy a 3v dc battery pack and solder the pin on

[Chromatica]

Clever

[napoleonis]

cool project.

[rise_against]

Thats cool.

[WonderWheeler]

I checked the Tecate link, and saw a similar UltraCap, and noticed it was marked "low-resistance". It didn't mention how low. I wonder about standby losses. How fast does the capacitor bank lose power in standby mode I wonder?

[MikeTheMaker]

I'm using some UltraCaps in another application and the voltage drops about 7% in 24 hours. I haven't tried or noted longer periods, so my information is limited.

[WonderWheeler]

That means by my rough calculations, you'd lose 25% in ten days. Not good for a flashlight you might stick in a drawer. Probably'd need a solar cell or two (and enough ambient light and a diode) if you wanted to use it for emergencies.

[Crusher7485]

No, for an emergency light I'd use alkaline batteries. This would be great for a flashlight you use a lot.

[jeremiahthebullfrog]

Wow I thought this technique could only be done with glass. This will make things much easier for me than using a saw.

[flowerrajan]

can i know the time that it works after the charging

[neumanngregor]

I got a pair of 470uF 200v capacitors from a old PC source, are they usable in this project, or will they blow up the led ?

[Colonel88]

uf is too small (I think) I have a 1 Farad capacitor, except it is INcredibly large, like the size of a plastic bottle cap. u should use one of these.

[neumanngregor]

you are right i played with a pair of 2200uF and i get som seconds of power for a red led ... i need some big value capacitor and of the rite value, 1F at 350V is not that good as a 1F at 3V (wiki and googled for that info) :)

[gottaseegottaknow]

theoretically, could you apply this project on a larger scale maybe even on a laptop? I mean, if you're a college student and you run through a full charge cycle just about every day, most laptop batteries would barely last a year or two before becoming virtually useless...

[I_am_Canadian]

Thats the book I won! :-D

[DELETED_rockstarmike000]

(removed by author or community request)

[XOIIO]

Simple, if you solder it the wrong way, or make a short, the capacitors will overheat, exploding and spraying boiling oil everywhere. I've done this at home, ill post a vid soon, the force can be quite powerful, and it hurts your face!

[chuckr44]

There's oil inside capacitors?

[XOIIO]

if they are electrolytic, yes.

[dumpy93]

I have a better solution for a batteryless flashlight. Plug it into a wall it doesn't use batteries that way

[jack zhang]

How much is the value of the capacitors? Could you please introduce the principle ?

[macrumpton]

Cool project! I am not sure why you want to build the case when you could get acrylic tubing or even use pvc if appearance is not paramount. You could even use clear plastic flexible tubing and put the switch inside so you have to squeeze it in a certain area to turn it on.

[ItsTheHobbs]

I have everything I need, I'm bored, and I want a rechargeable flashlight. Off I go to make this!

[dombeef]

Did you make this?

[ItsTheHobbs]

No, I realized I don't have the jack...

[Wesley666]

try a USB plug, would make a good USB project.

[ItsTheHobbs]

That's a good idea too.

[dombeef]

Oh OK

[dombeef]

You could change the jack with a nine volt battery adapter

[ItsTheHobbs]

Oh yeah... I have one of those, cool. I'll definitely make this when I have some time in between homework.

[TZENOV]

It's Working. I made something similar !!!!!!!! (The main problem is that the light is gone too fast for about a minute,a minute and a half.So I take and put two resistors one in the begin and one in the end->the voltage is 9V.)

[MikeTheMaker]

Great! Sounds like you're off to a good start.

[Wesley666]

If the values of the capacitors are 220 F then where do you get them. If they are 220 uF then you should try 10 000 uF caps.

[verdastel]

I guess the author meant to write 220 uF instead of 220 F. As far as i know, the size of 1 F capacitor equals a coca cola's bottle (and extremely expensive).

[Wesley666]

this should be tryed with 10000 farad caps, would work better then.

[Wesley666]

ya thats what I thought, and 1 farads are used in car audio mostly, i think.

[verdastel]

Umm, i change my supposition. I think he really means 220F. I checked the Digikey website and they produce capacitors with values up to 5000F. I apologize to the author for having doubted him with my limited knowledge :)

[Wesley666]

wow. my bad.

[ReCreate]

how long does it stay on per charge?

[ElementAngel29]

hey guys i am new to this - so i was wondering how important it is to use a 3volt charger - all i can find is a 3.7 volt -350 ma- will this work or do i have to buy a 3 volt charger. thanks -

[thecookiemonster]

voted 4 u! very cool idea and a good instructable!!!

[thepaul1993]

How long does it last for?

[Learndy]

That's impressive! Using two capacitors of 220F each in series you get 110F at double voltage. If you use a bright white LED (e.g. Digi-Key #C503B-WAN-CCACB151-ND or #C503B-WAN-CCACB231-ND) sucking 20mA you need about 1.5 hours to discharge the cap by 1 V!

I am currently working on a regulated Joule Thief circuit. With such a circuit we could run an (almost) arbitrary number of LEDs on a single 1.7V cap with contant brightness while the cap is discharging.
--
Airspace V - international hangar flying!
http://www.airspace-v.com/ggadgets for tools & toys

[MikeTheMaker]

I hope you post your circuit when you get it done--I think a lot of people will be interested.

[Learndy]

Yeah... here we go. Sorry for the delay. Have been out of lab for a few days. Let's go step by step:

I have attached an image showing the schematic of a step up converter also known as boost converter. Similar circuits are used in numerous joule-thief projects. This circuit runs on a single battery and delivers 6 V with two bright white LEDs. Oh, I forgot: We run without batteries. However, with this circuit you can use a single low voltage capacitor charged to 2.5 V or so until it is discharged to 1 V or even less. And at the same brightness - no matter how charged your capacitor is! Okay, you have to pay a price. The power efficiency is less than 100%. My first prototype has about 50%. Don't worry, this is improvable. And you probably get even more from a capacitor charge than without circuit...

All parts can be ordered at major electronics stores like Mouser, Digi-Key, Farnell. I ordered mine at Digi-Key at a total price of some EUR 2.-- (< $3.--). The The inductor L1+L2 is self-wrapped. I used .3 mm(12 mil) enamelled copper wire. How it is done:
o Wrap a small piece of paper on a AA battery.
o Fix it with scotch tape. Paper to paper, the battery remains movable.
o Cut 6 m (20 ft) of the wire.
o Fold it once that you get 3 m (10 ft) of double lead wire.
o Cut it at the fold in two wires of 3 m (10 ft).
o Mark both ends of one wire. Simple knots are fine.
o Wrap both wires together around the paper. No regularity needed, but keep it narrow.
o Fix the wires by knotting, glueing - be creative!
o Remove paint from the ends of the wires. (First burn it, then scratch it.)
o Find opposite ends of the wires. Hope you have fixed them not too thoroughly:
o Connect the wires to get a coil that is wrapped in one direction all the way and has a tap in the middle.
o Remove the battery.
o Fix the wire! Otherwise it yould slip from the paper wrap.It should stay in shape.

This was the hard stuff. Get all other parts and solder them together. I managed to connect them on a 16 whole PCB yesterday. Okay, I'm cheating. I connected C1 to the supply wires directly... Anyway, if you have some space you can use a larger PCB or even a breadboard for testing and experimenting.

You see two LEDs in the schematic. That's how I built it. However, if supply voltage is lower than the spcified voltage of all LEDs connected serially you should be able to use 1 to 4 or more LEDs. However, take care of the voltage resrtictions of transistors, diode, and capacitors. There is also an option of parallel connecting several LED series but this is too much for tonight.

Oh, why experimenting with this circuit? You can try different number of LEDs. You can change R2. The current through the LEDs should be somewhere near .7V / R2. With 47 Ohm you should be safe for almost all LED types. Try to reduce it a little to get more light. You can also try different coils. These days reasonable ferrite beads are not that easy to get. However, using one might increase efficiency.

And now for something completely different. There is another option to add some circuit. I ordered a few 20F capacitors for first experiments. No, I haven't started yet. Will do that tomorrow or on Wednesday... Why? Well, I read the data sheet and it says that the charge current limit is 500 mA. Exceeding this limit might harm the capacitor. Reducing capacity and even in a way you won't like for such an expensive device like gas production, fire, or explosion. I have developed a circuit to gracefully charge a capacitor regarding its current limit and voltage limit. The bad news i that I have to visit the local electronics shop to get a few parts. First testing, then publishing. Stay tuned.

You are still online? Great! There is an important message: VDD is negative voltage and GND is positive voltage in the circuit since we are using PNP transistors! Wrong connection won't work and might damage capacitors in the circuit.

Thats it for today. Quite some stuff. I should make it an instructable of its on since I also have an interesting mounting idea...

[MikeTheMaker]

Very nice--and a lot of work! Thanks for sharing. Obtaining a steady output from the discharging ultra capacitors is necessary for most devices. You've done a great job in getting us to think about this challenge.

[isacco]

This project is very useful and it seems great to me. A complete charge in a few minutes could represent a major technical breakthrough. Are you aware of any drawbacks? Do the capacitors provide a quite constant voltage as batteries do? If yes, possible applications for portable devices are easily foreseen. Do you know if this capacitor-based battery could be adequate for electronic devices, such as MP3 players or mobile phones? Congratulations

[MikeTheMaker]

There are two or three drawbacks. As you suspected, the capacitors do not provide a constant voltage, but discharge pretty much in a straight line (voltage down 50% when charge is 50% gone). That would take extra circuitry to maintain a constant voltage. The capacitors are more expensive than batteries and heavier than batteries for the same output capacity. On the positive side, the capacitors can be "recharged" hundreds of thousands of times and they will accept a charge very rapidly. Applications that aren't too voltage sensitive (like cordless screwdrivers--there is such a commercial product) will be first out of the gate. Manufacturing improvements and "quantity of scale" may make them much more competitive in the near future. Technically, the things you suggest are possible, but cost will keep them off the market for a while. I like your idea of using them for mobile phones--there will be a lot of dollars there when someone overcomes the cost issue (Go for it--it might be your ticket to riches!)

[isacco]

After my previous post I explored the web and I discovered that there is lot of Research & Development investment on this.

http://www.worldandi.com/subscribers/feature_detail.asp?num=23938
http://www.ultracapacitors.org/
http://web.mit.edu/newsoffice/2006/batteries-0208.html

This proves that your Instructable is at the cutting edge of technology!

[ReCreate]

erm...no its actually...50s technology Thats when capacitors first appeared(around that time)

[ElementAngel29]

hey um digikey doesnt continue the 220 microfarad capacitor - anyone know if like radioshack has them or something-- or does it have to be 220 ?

[MikeTheMaker]

It doesn't have to be 220, Mouser electronics, mouser.com has a 150 farad unit, available (which they will sell in quantities of one or more) for around $28. The part number is 647-JJC0E157MELC DigiKey has a 200 farad unit available, but they are wanting nearly $50. for it (which is way too much). The Tecate group has better pricing, but they have a minimum quantity of 4 on many of their units (you can get four 350 farad units for $100--$25. each) if you can find someone to share. http://www.tecategroup.com/ultracapacitors/productfinder.php

[frollard]

Thats an amazing project - I want your book! Wont that LED need a current limiting resistor, or dc-dc led driver? those caps are a direct short circuit thru that led. I'm surprised it doesn't explode :D

[MikeTheMaker]

As long as the voltage is low enough (under about 4 volts), the LED is fine. A dc-dc driver would be a good idea, but I was going for simplicity.

[frollard]

but the supercaps in series can charge to ~6 volts :S You have to be really careful, the miliamps jump from the usable 20 to approx 80 at an overvoltage of only .5 If you're dropping 50 bucks for supercaps, a 3 dollar driver board would be a good plan :D

[MikeTheMaker]

The particular supercaps I used are rated at 2.3 volts each--so I was more worried about putting too much voltage on them than the LED. I couldn't find the driver boards (without tearing apart a solar light) or building my own. Do you know of a source for driver boards at around 3 dollars?

[Scott_Tx]

dealextreme.com is where I get current regulators for my flashlight mods

[cirano]

would you mind putting up the SKU at dealextreme? Thanks

[Scott_Tx]

There's several of them depending on the amps needed and volatage input

[MikeTheMaker]

Thanks, I'll check them out.

[frollard]

Scott beat me to it - they're slow to ship, but they have some top notch rare items :D

[chuckr44]

I can tell you the store-bought shake lights I bought are crap. They do use capacitors, but they take a lot of shaking to recharge them. And after 5-7 days the charge is completely gone. So it's not true that caps retain their charge for a long time. However, if I can get some high-quality caps, and fix up my shake light, perhaps also with a rotary charger, then I might use that light more often.

[MikeTheMaker]

You are right--there is a leakage factor on caps (which I'm sure varies depending on cap construction)--so that has to be considered when designing capacitor powered devices.

[Dr.Bill]

I just saw the Tecate website. The caps the have are balanced they say so there is no need for external regulation. Did I get that right? Am I to understand there is no need for current limiting or is the circuit just to protect the caps. If you get a big enough cap bank and a wind generator you could power your house without batteries. Or maybe from Lightening Bolts!! YEAH THATS IT!! I LIKE LIGHTENING!!!!!!!!!!!!

[ewilhelm]

Ha! When I was running Squid Labs, prior to Instructables, we once got a proposal to design lightning-powered electricity plants. The potential client said that he was sure there was a tremendous amount of energy in each lightning bolt, and that if we could just figure out a way to capture and distribute that energy, we could both be rich (he was willing to split all future profits related to his "idea" in return for our work actually developing the system).

[MikeTheMaker]

Ben Franklin (never known as Mr. Safety) came up with a system to let him know about upcoming electrical storms (so he could go out and play). Known as Franklin's Bells, this is probably not advisable around buildings or people you ever want to see again. However, using an old tube type computer monitor (or your old analog tube tv), you can simulate Mr. Franklin's work. Look at
http://video.search.yahoo.com/video/play?p=franklin+bells&ei=UTF-8&fr=yfp-t-501&fr2=tab-web&tnr=21&vid=0001146035835
to see how this can work. Search "Franklins Bells" for more information.

[Dr.Bill]

There is a battery pile that was made in the 1700's. It had a brass ball hanging on a bar at the top from a silk thread down between 2 brass bells that would just ring all the time. Well, it's still ringing today and it is part of a collection belonging to Yale University. Cool Huh ?

[eeeXsmart]

nice instrutable! i have 680 uf, 200 WV capacitors. could i use them in your instructable? or could i use them in a circuit with 5 volt regulator? please help.

[MikeTheMaker]

I'm afraid that 680 uF just doesn't store enough energy to do this project. As Alex suggests below, charging them with 200 volts is risky. It takes at least 1 farad to get a few seconds of illumination.

[Sandisk1duo]

680uf, is pretty low...

don't charge them with 200v! ^{although they can withstand uch more then that, it's dangerous}
_{you'll need high capacity capacitors}

[brokengun]

Are you sure this thing can run for over 24 hours? Judging by how much the led is drawing (20 mA) and the energy available in the capacitor... my calculations give me a maximum of about 7 hours... Are your capacitors wired in series or parallel? It is kind of unclear in the picture.

[MikeTheMaker]

They are in series. Your calculations are probably correct, but the current used by the LED drops as the voltage of the capacitor decreases. If (as some of the other people have suggested) there was circuitry to hold the voltage up (and current draw and light level also held up), then your 7 hour period would probably be about right. After two or three hours, the flashlight is more like a "night light," but it will continue to glow for more than two days.

[Kiteman]

This is an excellent project - well worth the feature.

[santy22]

can i get this capacitors form something? like a power supply of an old PC?

[MikeTheMaker]

I have seen some 1 farad 5 volt "memory backup" capacitors in old PC's, but I'm not sure where you might find the larger ones (used). Anybody seen supercaps in a product?

[mr. blue]

wow. i feel so dumb, i would of never of thought of that.

[parafoil]

About how much did you spend? Thanks in advance...

[MikeTheMaker]

Most of the expense is in the capacitors, about $50.00 for the pair. The rest is a few dollars, depending on what you happen to have around the garage.

[artemff]

I didn't quite get an idea of connecting the capacitors in series.
If one wants to increase the capacity, one has to connect them in parallel:
http://www.allaboutcircuits.com/vol_1/chpt_13/4.html

Second thing that bothers me is the using if an external battery. It would be more useful to have any small "generator" to pump energy to the capacitors.
Coil with moving core and diode rectifier is the first that comes to mind.

Good luck with your experiments :)

[MikeTheMaker]

I went in series to boost the voltage (each cap was only good for 2.3 volts) and I wanted more voltage to run the white LED direct (without other circuitry). You are correct that my capacitance gets cut in half when I put two in series. Charging the capacitors takes a pretty strong energy source because--in two or three minutes--you are putting in the energy that comes out over several hours. I'm going to Maker Faire with a human powered generator and a "big" bank of capacitors--if you can get out there, come by and check it out.

[fwjs28]

that looks pretty sweet....how long does the light work?

[MikeTheMaker]

It shines brightly for two or three hours--but shines enough to be a night light for 36 hours or longer.

[PKM]

Holy ****, you can get 220F capacitors? I kind of want to get five so I can have a kilofarad- there's a certain geek pride in breaking a new unit like the terabyte or the petaflop :) I make a 220F capacitor at 3V almost exactly 10,000J, which is 3,333 amp seconds or about 925 mAh. Given an average NiMH AAA battery has 900mAh, that makes one of these capacitors roughly equivalent to two NiMH AAA batteries! And it recharges in a couple of minutes! I need to get a couple of these for my MP3 player... we live in the future :)

[MikeTheMaker]

Try out this place:
http://www.tecategroup.com/ultracapacitors/productfinder.php
I purchased some really large capacitors for another project.

[fwjs28]

Whoa...that sounded like geek jargon flying at me at over 9,700,300.284 miles a milisecond!...lol...so im just gonna shake my head up and down and act like i understand...

[PKM]

Hehehe sorry, I have a tendency to work out stuff like this to make it clearer in my own head (but possibly less clear in everyone else's :P). If you ignore the "show your working" part in the middle, I just figured out that each one of these capacitors can hold the same amount of energy as two rechargeable AAA batteries, which is pretty impressive for a capacitor.

_{yeah ignore the bit about kilofarads as well..}

[fwjs28]

wow! thats awesome

[luxstar]

I recently made a supercapacitor flashlight that requires no batteries. I charge it off of a 5 watt solar panel. The larger capacitors of this type are usally quite expensive but the $10.00 2600 farad capacitors are back for now (on home page of Goldmine-Elec plus others on boost cap page).
Here is the link plus the link to instructions, diagrams, and pictures of the flashlight.
http://s247.photobucket.com/albums/gg153/luxstar/
http://www.goldmine-elec.com/