# My DIY Joule Thief Hurricane Lamp Project: Lots of pics!



## Darvis (Mar 14, 2011)

All,

I wanted to sit down and give a little back to CPF since it’s been so good to me over the past few years; I have learned much here from a lot of real smart folks!!

I have long been dying to dabble in a bit of circuit building, so naturally, I thought I’d start with a pretty easy and fun circuit that we all may know and love: The Joule thief… yes, It’s been discussed here before, and in many other places, so not something really new, but:

The twist is that I took the concept and made it into a AA emergency (hurricane) lamp using parts found in basically any electronics and hardware store (I shopped at the well known major chains). I thought this would be a fun and practical project for the family.

For those that are new to this, like me, the Joule thief is a very simple circuit that essentially boosts the voltage of any AA battery (especially ones that appear to be dead from a remote control or kid’s toy) so that It can power a white or blue (or any) LED that requires a forward voltage (vf) of about 3.3 volts. I did not know this coming into the hobby, but diodes (LEDs) have very specific voltage requirements and will not run when the voltage is too low, hence the need to boost the voltage source.

So, parts, here we go (total cost for this project, btw, assuming you have the tools: ~10-15 bucks)

1.25 inch PVC repair coupler (bigger if you want to use D batteries)








5 gallon bucket lid (for caps and the circuit board) the plastic that these are made out of is super pliable and easy to cut, but is also quite sturdy; a great combo for all sorts of parts.







One switch. I highly recommend the Gardner Bender model GSW-24 push button lamp switch that I got from the major chain hardware retailer. I tried cheaper toggles and they were terrible. These puppies are way over-engineered for this project and come with pre-wired leads. Well worth the 4 bucks.







And here’s a look down the tube at how the switch mounts on the inside:







Some phone wire or cat 3 wire, or any thin gauge solid wire… You’ll need this for winding your coil and all of the rest of the leads

One 2N 3904 transistor (or 4401). Buy a pack of these as the little leads are fussy and I snapped more than a few off, be careful with these!! I mount them and leave them alone!!!

One 1k ohm resistor

One Ferrite Bead for making the coil

One white or blue led with a vf of 3-3.5 volts

AA battery holder

Drill and bits, wire strippers, soldering iron and solder, pliers, wire nippers, electrical tape and/or shrink tubing (found at any hobby or electronics store)

So first things first, I drill a 3/8” hole in the side of the PVC coupler for mounting the switch. Your bit size needs will vary depending on which switch you buy/prefer; but for the model above, this bit works with just a bit of reaming.







Next, I cut some bucket lid to fit inside the coupler ends to make the bottom and top caps







Using a 3/16” drill bit, I drill the Led hole in the upper cap, nearest the switch (a 5mm LED will fit perfectly through this and hold nice and tight with no glue) The skirt on the bottom of the LED will keep it perfectly set in the hole and will not allow it to pop through. You’ll see some better pics of this in a bit.







That prep done, I then make the “circuit board” using another little square piece of lid and a 1/16” drill bit. Not rocket science and you can drill this out any way you like. You’ll see this in a bit.

That prep out of the way, I then go to work on the circuit. Now I’m not going to diagram out the circuit as there is tons of info on the internet about how to craft this little gem and I think half to fun is researching this; but I’ll add some lessons learned here to make things a bit easier. That said, look up “joule thief” and go to the link for the “evil mad scientists.” This particular video was all I really needed and they also have a very detailed toroid winding tutorial with great, detailed pictures. 

First, I highly recommend using a breadboard to get it right the first time; it will save you tons of headaches!!!!
Then, one must wrap the coil, and this is the trickiest part… I have found via trial and error that one needs at least 10 turns to get the right voltage boost. I went with smaller coils at first with fewer wraps and had dim LEDs, took me a while, but I came to this conclusion after some frustrating attempts on the breadboard. Do this part right!!! It pays off big in the end. After you are done, wrap that puppy in some electrical tape because if the wires come loose and cross, it will not work!!!

Next, take your bread board circuit and mount everything up on the board; make sure you leave leads for the battery and LED. I test this once before putting it all together. Here’s that circuit board I mentioned earlier… and a bottom view of the LED mounted through the hole. No shots of this, but all connections are soldered in the back of the board.







Solder it all together in the light. The switch is wired between the negative lead from the battery and the board. The positive lead is wired right to the battery holder. I typically use red for positive and black for negative to keep it all straight. All the extra wire also helps keep things from bouncing around inside. Make sure to put your shrink tubing on first!!! But no worries if you forget, it’s nothing that can’t be fixed with some electrical tape.







It’s a tight fit! Just sort of stuff it all in there and use care when shoving the coil on down in. I actually try very hard to kind of make things fit nicely and not twist the leads. Wrapping the whole circuit board up in electrical tape helps a lot, you’ll just have to fiddle with it.

















Here’s a view of the battery/bottom end:







Once it’s all together, click and enjoy!!!







I used PVC end caps at first on the top, but quickly settled on the end cap that comes with the coupler and bucket lid piece as the recessed LED works better… no annoying shine in the eyes since this thing really needs to ceiling bounce anyway.

Another thing is that some will say the Joule Thief will take a AA down to .30 volts, but I only get to about .70v- Might be the smallish coil, but I’m not complaining as this thing seems to run forever off a fresh AA.

My eyeball integrated sphere calculations put this powerhouse at about 5-10 lumens, surprisingly bright in pitch black with dark adapted eyes. Heat from the LED (HA!) is not an issue and things got real kooky when I built the big “triple” which I actually recommend one shoots for. It’s really the best in terms of output and is super easy to do, just wire three LEDs in parallel, no magic needed. I drilled a triangle hole pattern and put it all together. 

Build your first light as a single to get it right (you’ll want to build lots of these once you get going anyway) then build the triple for real world use. The output difference is noticeable and any beam artifacts from the cheap LEDs tend to go away with the triple.







I also ordered some higher quality higher output LEDs online and will see what they can do…

My kids love these things and decorate them with all kinds of stickers and such, I’m going figure out how to add some GITD epoxy to mine for that “find it in the night” feature. Hope you all enjoy them as much as I do. Please feel free to PM me with any questions or if I need to clarify anything in this thread.

Please also post pictures of your builds (if you build that is); I’m eager to see what other mods/ideas people come up with.

Darvis

Update: A couple of things I've tried in the last day since this post...

Got some real nice basic ferrite beads from a website called kits and parts; so if you're wondering where to source these, this would be the place. I went with the FT50-43 beads and was able to get 9-10 wraps on the toroid. All brightness was the same vs. my other beads and a straight 123A

Also received and tried some great 15 and 30 degree 5mm LEDS that were 18,000 MCD from Super Bright LEDs. the 15 degree ones are a little blue, but not too bad. Going to mount the 30 degree ones in the triple and see how it goes, but these are definitely the brightest I've tried yet and worth getting for this project


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## Darvis (Mar 14, 2011)

Mods: I should have posted this in the homemade flashlight section, sorry about that. Please move as necessary.

Regards,
Darvis

EDIT: Thanks!!!


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## PCC (Mar 15, 2011)

That's a nice little light. You've encouraged me to try my hand at making my own Joule Thief lights.


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## Darvis (Mar 15, 2011)

PCC said:


> That's a nice little light. You've encouraged me to try my hand at making my own Joule Thief lights.


 
Thanks, It's come in handy more than a few times over the last week. Let me know if the steps above help/work for you and if I need to clarify or elaborate on anything. I'm interested to see what you come up with, so post it here when you're done and good luck!!


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## bstrickler (Mar 15, 2011)

You can actually make a Joule thief with only 2 components now.

http://www.mouser.com/Search/Produc...TAvirtualkey52230000virtualkey522-ZXSC380FHTA
http://www.mouser.com/ProductDetail...=sGAEpiMZZMsVJzu5wKIZCbTeDXLH31lgzP16QE4Fnjg=

You might need a power LED, though, because it's putting out about 50 mA at 1v input.

I'm definitely ordering a couple of those next time I order from mouser, and havin a little fun.

~Brian


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## PCC (Mar 15, 2011)

Will do. Thanks for the instructive post.


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## Kestrel (Mar 15, 2011)

I love your "triple" - My Moddoo dropins are jealous.


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## Darvis (Mar 15, 2011)

bstrickler said:


> You can actually make a Joule thief with only 2 components now.
> 
> http://www.mouser.com/Search/Produc...TAvirtualkey52230000virtualkey522-ZXSC380FHTA
> http://www.mouser.com/ProductDetail...=sGAEpiMZZMsVJzu5wKIZCbTeDXLH31lgzP16QE4Fnjg=
> ...


 
Now that is way cool. If I understand the spec sheet correctly, it looks like mA can be set via inductor selection? That would really make things easy, though, just buy a pre-made inductor and this and go to town!! Thanks for the heads up, I think I'm going to buy a few myself and play around with them.


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## bstrickler (Mar 15, 2011)

Darvis said:


> Now that is way cool. If I understand the spec sheet correctly, it looks like mA can be set via inductor selection? That would really make things easy, though, just buy a pre-made inductor and this and go to town!! Thanks for the heads up, I think I'm going to buy a few myself and play around with them.


 

Yep, just choose a 22, 47, 68, or 100 microhenry coil, and you'll have customizeable output. Next thing to do would be to make a 3-level twisty (22,47,100 microhenry, since 68 is almost the same output as 47). 3 coils, 1 microprocessor, and the ZXSC380. Sounds like a challenge I'll have to try!


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## Darvis (Mar 15, 2011)

So, if I don't want to poof my 20mah LED at 1.5 volts or less, which inductor would I get..? not sure I fully understand the spec sheets. I think it would be 47mh, but not 100% sure on that.


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## bstrickler (Mar 15, 2011)

Page 6 shows this as the output at 1.5v

100uh=19ma
68uh= 16ma
47uh=15ma
22uh=10.5ma

~Brian


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## Darvis (Mar 15, 2011)

bstrickler said:


> Page 6 shows this as the output at 1.5v
> 
> 100uh=19ma
> 68uh= 16ma
> ...


 
Thanks Brian, I thought that's what I read, but doubted what I saw.. Appreciate the info, I'm going to try me a two part joule thief!!


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## Darvis (Mar 15, 2011)

Added some info at the bottom of the original post on ferrite beads and LED's


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## bstrickler (Mar 15, 2011)

Darvis said:


> Thanks Brian, I thought that's what I read, but doubted what I saw.. Appreciate the info, I'm going to try me a two part joule thief!!


 
No problem 

Glad I could help. Let me know how it goes!

~Brian


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## flatline (Sep 4, 2011)

bstrickler said:


> You can actually make a Joule thief with only 2 components now.
> 
> http://www.mouser.com/Search/Produc...TAvirtualkey52230000virtualkey522-ZXSC380FHTA
> http://www.mouser.com/ProductDetail...=sGAEpiMZZMsVJzu5wKIZCbTeDXLH31lgzP16QE4Fnjg=
> ...


 
For those of us who are new to this, could you give some explanation on how to use these two components to make a joulethief? I think I understand what I'm reading, but I'm not confident.

Thanks!

--flatline


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## Darvis (Sep 8, 2011)

Flatline,

The inductors act as the coil and contral the mA output that drives the LED. The microprocessor eliminates the need for both the transistor and resistor (and a lot of the wiring).


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## ilight (Sep 9, 2011)

http://i1196.photobucket.com/albums/aa403/greeninventions/gtf.gif
http://i1196.photobucket.com/albums/aa403/greeninventions/jtfe.jpg 
made by ife team


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## ilight (Sep 9, 2011)

flatline said:


> For those of us who are new to this, could you give some explanation on how to use these two components to make a joulethief? I think I understand what I'm reading, but I'm not confident.
> 
> Thanks!
> 
> --flatline


 new here
http://i1196.photobucket.com/albums/aa403/greeninventions/gtf.gif
http://i1196.photobucket.com/albums/aa403/greeninventions/jtfe.jpg


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## Justin Case (Sep 15, 2011)

Maybe the one main downside to using the ZXSC380 is the datasheet's 0.8V min input voltage spec. A basic Joule Thief can run with around 0.6V input (possibly even lower than that), although the output is probably quite low. However, if you can feed the JT with 0.7V input, you can get some useful light.


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## tylernt (Sep 18, 2011)

http://www.candlepowerforums.com/vb...boost-driver&p=3546854&viewfull=1#post3546854


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## PCC (Sep 18, 2011)

I wonder what circuit they use in the old Nite Ize 3-LED Mini-Mag drop-in? Mine will power up just fine on batteries that won't light up my datiLED made toroid Joule Thief. I won't even try using them in 2AA Mini-Mags anymore because they'll run down the AA alkaline cells so badly that it's a guaranteed leak waiting to happen. I have them in cut-down MMs.


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## Darvis (Sep 19, 2011)

tylernt said:


> http://www.candlepowerforums.com/vb...boost-driver&p=3546854&viewfull=1#post3546854


 
That's just plain amazing!! I wish I was that good at this... I've gotten mine down to some pretty small tube sizes for some nice compact lights now and have found some great LED holders and such, never dreamed they could be that small, though.. I gotta see if I can replicate those.


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## Justin Case (Sep 19, 2011)

A Joule Thief installed within an MES bulb base.


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## tylernt (Sep 19, 2011)

Yeah, I like the ZXLD381 because it's uber-small and only requires one other component. Cheap too. However, a pair of helping hands is really indispensable.  

For my SMD inductor, I used 587-2053-1-ND / LBR2518T220K (22uH). You could also use a 15uH with the ZXLD381, but you risk blowing or fading a 5mm emitter as peak current (120mA) exceeds the LED's rated maximum... for a high quality Cree or Nichia I suppose that's less of a concern than with cheap noname LEDs.


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## eternity (Sep 19, 2011)

Okay gotta make myself one of these in case another hurricane swings by my place. Of course I don't know if I can trust my own handy work in an emergency. Guess I'll have to save up for another light, just in case.


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## Justin Case (Sep 20, 2011)

I built a JT on perf board (not one of the above super miniature JTs) using the classic circuit. It can light a 5mm LED down to Vin=0.55V.


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## cnjl3 (Sep 20, 2011)

Does that mean that you check the voltage across the battery when you turn the JT circuit on? Or do you measure the voltage before you turn the JT circuit on?
I just made one of these little jewels and it made me smile when I powered up the 5mm LED. I used the website recommended above [FONT=&quot]http://www.kitsandparts.com/toroids.php[/FONT]
and bought 50 transitors and 25 ferrite coils dirt cheap so I guess I will be make a "few" if these JT circuits.

Thanks! Daryl for the info.



Justin Case said:


> I built a JT on perf board (not one of the above super miniature JTs) using the classic circuit. It can light a 5mm LED down to Vin=0.55V.


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## Justin Case (Sep 20, 2011)

Vin with the circuit running, i.e., under load.


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## Darvis (Sep 21, 2011)

Tylernt, where do you source your parts? I found the ZXLD on mouser, but not the inductor... maybe I just got the part numbers wrong?

Ah.. nevermind, digikey!!


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## tylernt (Sep 21, 2011)

I got my stuff from Digi-Key, but I'm sure Mouser sells several suitable inductors -- just look for one that can handle the peak mA you intend to push through the LED with a comfortable safety margin. For a 22uH inductor, for example, the ZXLD381 needs an inductor that can handle at least 80mA+. Once you find some inductors that can handle the juice, then just look for the one with the lowest resistance. Should work fine.


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## Darvis (Sep 22, 2011)

Thanks!! I found the parts.... So, wow, I really think I'm going to give this a try... the parts are cheap!!! And your thread was great as well... 

I may need to ask you some questions when I get the parts, though, as I am just learning this stuff and I'm not entirely sure I'll know what to solder to what. My perfection of the lamp has purely been cosmetic and I've made my basic circuit more compact, figured out a few things here and there, but have not yet deviated from the classic JT parts as of yet...

You have all been a great help with this, I need to get some newer pictures up of some recent builds, including my dual circuit, dual LED lamp with selector switch and both warm and neutral LEDS!! Woohooo!!


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## Darvis (Sep 28, 2011)

Complete and utter success with my first ZXLD circuit... unreal!!! Man, it really reduces the footprint. I have to admit, I was not prepared for how small the components really were and probably made this first one bigger than it needed to be, but it works!!

Here it is next to a traditional JT circuit:







This may be a totally bad practice, but I was having trouble getting everything to stay in place to solder, even with the helping hands, to, er... help, so I simply used a drop of crazy glue to hold the parts in place and it worked great...


Now I just gotta get it into a host.


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## tylernt (Sep 28, 2011)

Yeah I was a little surprised when I got my first ZXLD381 too, sneeze and that thing is gone!


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## Justin Case (Sep 28, 2011)

I'm interested in how low the Vin can be and still start up the ZXLD381 and how low the Vin can be to keep the ZXLD381 running. I've gotten startup and good output from a AA alkaline with less than 0.9V open circuit, and 0.549V under load using the basic JT circuit.


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## Darvis (Sep 28, 2011)

So I was able to get the new circuit integrated into a host....






From right to left: A 1.25" compression host with 2 JT circuits each driving one LED with a single pole, double throw switch with center off. This allows the use of one neutral LED (brighter) and one warm LED (low mode) depending on the needs. If you look close, you'll see the second LED towards the front, in front of the rear (lit) LED

Next to that is what was my standard build using a 1" compression fitting and an on/off toggle... this was about as small as I was getting it...

Enter the ZXLD (third from the right) and now I'm in a 1/2" compression fitting and have eliminated the switch all together... Small, clean, awesome!!!!!! (well, awesome to me anyway)

For size reference next to a 6P and an 18650:






I have gotten my taditional JT down to .58-60v before in a straight run, but found it needed about .90 (as you noted) to actually start the circuit. Not yet sure about the ZXLD, but I aim to find out.


Oh, and here's a reading lamp that only a mother can love:


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## Justin Case (Sep 28, 2011)

Mine will start at ~0.5V from a bench power supply. The 0.9V referenced before is the OCV for a "spent" AA. I can run such a AA cell so that it sags to ~0.55V under load. Turn off the JT and immediately turn on the JT again. The circuit clearly starts back up since the LED lights up with a nice, bright, steady beam. Within that brief period of time, the AA cell certainly has recovered its OCV to no more than perhaps ~0.6V.


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## Darvis (Sep 28, 2011)

Makes sense. My guess is that I've duplicated your results without knowing it, if that makes sense. Because I've not actually measured anything other than the voltage of the battery going in and then coming out, I've not seen the the OCV recovery part of it, etc. 

I did experiment with different sized ferrite beads and windings to see if it would improve output or runtime (in other words, could I get down to .30v?) and found no real difference. There seems to be no gain from using more winds, or larger diameter wire- a good wind is a good wind it would seem... A bad, or crossed winding however, makes for some truly weak (or no) output!!! I learned that lesson the hard way.  It has to be done right, but over doing it gains nothing...

I can say that with my traditional JT circuit, the light does start to dim around .70v (this is based on me pulling NiMH batts for recharging) It's my indicator of when they need to be dropped into the old charger. I've run alkalines all the way to almost off and towards the very end, they're just barely glowing. But honestly, until that ~.65-.70 mark, there is really no perceptable change in brightness, so the circuit does provide some degree of regulation as well.

This has become quite the cool learning project!!!


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## Justin Case (Sep 28, 2011)

Do you know anything about the ferrite you have, e.g., AL value? How many turns are you using? It does seem to me that the basic JT circuit is fairly insensitive to coil inductance, as long as you are "in the range". I wound a powdered iron coil (Micrometals T44-52) with calculated inductance of only 2.8 uH and that circuit was very squirrely. It would work "bare" -- the parts all soldered directly to one another. But if I mounted the parts neatly onto perf board, it wouldn't turn on. Just a little change in how tightly the coil was wound seemed to affect the JT. When I wound more turns on the powdered iron core to get about 6 uH, the JT became reliable. I also have some ferrite cores (Epcos B64290L0044X038 -- T38 material) with very high AL (5100) and only 4 turns give a calculated inductance of about 80 uH.

Depending on what ferrite formulation you have, you might try something extreme like just one turn to get the min inductance to see if your JT will still work.

A Si transistor is not going to work well (i.e., at all) with only 0.3V. You'd have to go to germanium.


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## Darvis (Sep 28, 2011)

I do, this is straight off of the website I got them from and I'm getting 9 turns on mine using standard twisted pair phone wire (22ga?):

OD(A) = 0.5 in / 12.7 mm +/- 0.25 mm
ID(B) = 0.281 in / 7.15 mm +/- 0.20 mm
Ht(C) = 0.188 in / 4.9 mm +/- 0.25 mm AL=440 [SIZE=-1]+/- 20 %[/SIZE] uH=(AL*Turns2)/1000 
Actual measured AL using 10 turns #28 wireTemperature Stability (ppm /°C) = 12500Color Code = shiny blackApplication Freq Range
Wideband Transformers 5 - 400 MHz
Power Transformers 0.5 - 30 MHz
RFI Suppression 5 - 500 MHz

Now, I admit, I have NO idea what any of this means, I literally bought them based on their size. The website is actually pretty cool, it's called "kits and parts" and this bead is part number FT50-43

I will try what you suggested above and report back on what I get. I have the circuit rigged on a breadboard, so I can play with it as needed.


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## Justin Case (Sep 28, 2011)

FT50-43 means a ferrite core, 0.50" outside diameter, material formulation 43. #43 looks like it is spec'ed for EMI/RF suppression. For the JT application, you probably care most about the AL value, which relates the number of turns to the inductance. For 9 turns, the inductance is 440*9^2/1000 ~36uH (+/-20%). To explore the low end, I might try 2, 3, and 4 turns to see if the JT still works.


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## notrefined (Sep 29, 2011)

I'm also curious about the minimum startup voltage for the ZXLD joule thief...eagerly awaiting results


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## Cypher_Aod (Sep 29, 2011)

Hey guys, i'd quite like to make a couple of joule thieves, and i have one in particular that i'd like to ask about.
Basically, i have an ANCIENT Luxeon I Red-Orange emitter which i'd like to joule-thief-ify.

Hopefully this LED would be perfect for joulethiefing because it's low Vf of only 2.31V and a max rated current of 385mA so it's unlikely to get killed by fresh cells.


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## Darvis (Sep 29, 2011)

notrefined said:


> I'm also curious about the minimum startup voltage for the ZXLD joule thief...eagerly awaiting results


 
I'm going to be building one tomorrow and will begin tests after that, will definitely post results...


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## Darvis (Sep 29, 2011)

Cypher_Aod said:


> Hey guys, i'd quite like to make a couple of joule thieves, and i have one in particular that i'd like to ask about.
> Basically, i have an ANCIENT Luxeon I Red-Orange emitter which i'd like to joule-thief-ify.
> 
> Hopefully this LED would be perfect for joulethiefing because it's low Vf of only 2.31V and a max rated current of 385mA so it's unlikely to get killed by fresh cells.


 
All I can say is build the circuit on a breadboard and give it a try.... based on those specs, it should light right up. My guess is that the JT circuit is boosting to about 3.4v max as I can get LEDs with a required Vf of 3.2 to light, but I have one that requires 3.6 and it won't go. I never measured it and probably should... 

I have a bunch of cheapy red LEDs that came with these neat chrome LED holders that I bought and they light right up direct on a AA battery- I've also wired them into the JT circuit on my breadboard and they light up and don't poof at all. So they have a much lower Vf requirement and still run well at over a Vf of 3.0. Maybe they have that range, but my guess is the Luxeon is much more robust and can take it.


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## Cypher_Aod (Sep 29, 2011)

Darvis said:


> All I can say is build the circuit on a breadboard and give it a try.... based on those specs, it should light right up. My guess is that the JT circuit is boosting to about 3.4v max as I can get LEDs with a required Vf of 3.2 to light, but I have one that requires 3.6 and it won't go. I never measured it and probably should...
> 
> I have a bunch of cheapy red LEDs that came with these neat chrome LED holders that I bought and they light right up direct on a AA battery- I've also wired them into the JT circuit on my breadboard and they light up and don't poof at all. So they have a much lower Vf requirement and still run well at over a Vf of 3.0. Maybe they have that range, but my guess is the Luxeon is much more robust and can take it.


 
Sweet! I'll build a traditional-style Joule-Thief for now for maximum battery-drainage


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## Justin Case (Sep 29, 2011)

Darvis said:


> All I can say is build the circuit on a breadboard and give it a try.... based on those specs, it should light right up. My guess is that the JT circuit is boosting to about 3.4v max as I can get LEDs with a required Vf of 3.2 to light, but I have one that requires 3.6 and it won't go. I never measured it and probably should...


 
That's strange that the apparently higher Vf LED wouldn't light. Vf is not a single value. It depends on If. 5mm white LEDs should be able to light up at around 2.5V. A basic JT circuit ought to be able to boost a AA cell to at least that, even with a very dead cell. It'll be at moonglow level, but it should light up.

I'm going to test coil inductance in the opposite direction -- increased inductance. I have some Epcos B64290L0044X038 ferrite toroids. I figure if I wrap 15-20 turns, I could get 1-2 milliHenries.


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## Justin Case (Sep 30, 2011)

I wound 22 turns of 30 ga solid wire on the Epcos ferrite toroid and the JT was able to run on a very depleted AA Energizer alkaline. By the time the cell measured 0.502V under load, the 5mm white LED was basically in moonglow mode. But it's been running steadily for hours, whereas my basic JT with Micrometals T44-52 powdered iron core can't deal with this "dead" AA cell (the LED lights, fades, starts blinking, and goes out, all within a few seconds).

The rest of the two JTs are the same: 1Kohm resistor, 2N4401 transistor, and 5mm high brightness white LED. The calculated inductances are 2.5mH for the Epcos core and 6.9uH for the Micrometals core.


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## IcantC (Oct 1, 2011)

This is a great idea! Plan to make a few for emergencies.

Now a q for you guys, how can I mod this diy

http://www.evilmadscientist.com/article.php/nightlight

So my JT can run a white led and run off one or 2 aa?


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## Darvis (Oct 1, 2011)

Seems to me the easiest thing to do would to make that photo sensor circuit the input to the JT (the leads to the JT would take the place of the red LED in the design) It would control the power in and all you'd need to run it would be AA. I might have to give that one a whirl.

Jason... I did not get chance to play with windings as of yet, but plan to in the next few days.

I did confirm that my traditional (non-ZXLD) JT would fire up at .74v at least, more tests to come.


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## IcantC (Oct 2, 2011)

Darvis, if you can please try let me know! I don't have any parts or the aptitude to troubleshoot the circuit.

I plan to order some some stuff and try a basic JT, the darvis JT and then the light sensing one.


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## notrefined (Oct 3, 2011)

Darvis, did I read that correctly? The ZXLD based circuit will start and run from an OCV of 0.74v? Or is that start and run from a bench supply at 0.74V?


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## Darvis (Oct 3, 2011)

notrefined said:


> Darvis, did I read that correctly? The ZXLD based circuit will start and run from an OCV of 0.74v? Or is that start and run from a bench supply at 0.74V?



No, that was for the traditional JT circuit that I had on hand. Thanks for pointing that out! I edited the post to make it more clear.. I still have to build a new ZXLD and do some tests.


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## potpot (Oct 11, 2011)

Pretty interesting project. I'll be definitely building one (or more) of these for use as a battery drainer/night light around the house.


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## cnjl3 (Oct 25, 2011)

I have made a couple of JT's with the PVC repair coupler which included both a switch and battery compartment.
I decided to eliminate the battery compartment by soldering magnets to the end of my wires.
I used both 28 and 26 gauge wire on my ferrite bead - but I couldn't tell if one is brighter.
I like your idea of a "twisty" on/off so I went ahead and ordered some glass magnet switches so 
that I can twist on/off with a magnet. 
I don't know if you can see but I used part of a BlueBell ice cream stick to hold my components--YUM!


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## datiLED (Oct 26, 2011)

Here is my take on the ZXLD381 circuit. This is the version with a smoothing diode and capacitor. The circuit boards are 14mm, 10mm and 7mm in diameter. For reference, they are sitting on a dime. The circuit on the left is using a warm white XP-G LED, and is driven at 50mA. The other two circuits are driven at 18mA. 










I also have a thread about building battery drainers using the Joule thief circuits. I chose to use the Supercharged Joule Thief circuit from a weblog that appears to have been removed. It had lots of good information and testing data on the Joule Thief. Here is the schematic for the circuit. I use a 2N4401 transistor, and a small toroid from Mouser.


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## tylernt (Oct 27, 2011)

datiLED said:


> Here is my take on the ZXLD381 circuit. This is the version with a smoothing diode and capacitor.


Correct me if I'm wrong, but I don't think the XP-G needs the smoothing cap. The 5mms definitely do, but the XP-G should be able to handle the 380mA pulses no sweat?


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## datiLED (Oct 28, 2011)

tylernt said:


> Correct me if I'm wrong, but I don't think the XP-G needs the smoothing cap. The 5mms definitely do, but the XP-G should be able to handle the 380mA pulses no sweat?



The XP-G could certainly handle the pulses. For the cost of two extra components, I chose to err on the side of caution and design the PCBs with the smoothing diode and capacitor. Regardless of LED used, I build all of the circuits the same way, and change the inductor to set the current to the LED.


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## wquiles (Oct 28, 2011)

Most of these great small circuits are meant for a 1.5 volt cell (presumably discharged), but has anyone tried using discharged CR123 cells instead?


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## Justin Case (Oct 28, 2011)

My JT seems to work with a 3V Li primary (I used a Varta CR2 cell that measures about 3.1V open circuit). The SPICE simulation looks ugly but I guess that the rapid pulses save the 5mm LED.


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## tylernt (Oct 28, 2011)

The ZXLD381 datasheet says "the pulse control circuit ... requires the load voltage to be at least 0.8V greater than VCC. (The device will function with load voltages smaller than this but output current regulation will be impaired.)" I assume this means that you'll be sending a lot more current to the LED than expected. You could compensate by using a larger inductor, but some experimentation would be required... ideally, with a 'scope, so you can see the current peaks.

I'm sure a JT could be tweaked to run efficiently at a higher voltage, but I lack the electronics experience to know what to tweak. Maybe just use two LEDs in series?


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## wquiles (Oct 28, 2011)

Thank you guys - I will buy some parts to build one to "play" with 

Will


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## tylernt (Oct 29, 2011)

For those of you that want to experiment with the ZXLD381, here's a way to put it on your breadboard:

First, get some breakaway header pins. These could be desoldered from an old computer motherboard (IDE/floppy connectors, USB headers, etc). Stick the long ends in your breadboard like this:
[X] [ ] [ ]
[ ] [X] [X]




Cut a 2x3 grid of copper-ring perfboard and lay it over your header pins, ring side up:




Lay down the ZXLD381. The ground pin should be touching the top middle contact; the Vin and Vout pins should be touching the bottom middle and bottom right contacts. I used a little rosin flux on the SMT pins to ensure good contact:




Apply heat to the copper rings and feed in solder until things ball up. Deliberately create a solder bridge from the top middle contact (where the ZXLD ground pin is) to the top left contact (where the header pin is):




Now you can unplug and plug that teeny tiny SMT chip anywhere on your breadboard you like, because now it's a through-hole component!


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## Darvis (Nov 2, 2011)

Genius!!!


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## IcantC (Nov 8, 2011)

Can I use the same basic JT I I want to use 2aa? If not, what do I need to change?


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## IcantC (Nov 8, 2011)

Btw made a very crude JT with parts I found, it ran for over 72 hours straight off a used/dead AA! Testing again with a used/dead AAA.

Btw are lithium batteries safe to fully discharge with a JT? Or should I be worried about venting?


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## wquiles (Jan 2, 2012)

wquiles said:


> Thank you guys - I will buy some parts to build one to "play" with
> 
> Will



OK, so I got some ZXLD383's to play with:







I implemented this circuit, and I made my own PWB's as part of my most recent PWB pannel for the MagnetoDrive project:











Here is my first board - not pretty, but it works:











Just as Justin pointed out earlier, these will not work down in the 0.5-0.6 volt range. Mine did not work at 0.79 volts, but started at 0.80 volts:











Using a 4uH inductor, at an input voltage of 1.6V I had a healthy 250mA current going out of the power supply to an old 3W "U" bin Luxeon (remember those???):






I will try to measure the current into the LED sometime later this week 

Will


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## wquiles (Jan 3, 2012)

I know tables here loose all formating, but here is the Power_in vs. Power_out (and efficiency as Pin/Pout) that I got as I went from Vin of 0.8 volts up to 3.5 volts (where I was pretty much getting to a direct drive condition):

(these values are all using the 4uH inductor)

Vin	Iin	Pin	Vout	Iout	Pout	Efficiency (%)
0.8	0.013	0.0104	2.49	0.0001	0.000249	2%
0.9	0.045	0.0405	2.61	0.001	0.00261	6%
1	0.162	0.162	2.74	0.016	0.04384	27%
1.1	0.197	0.2167	2.81	0.031	0.08711	40%
1.2	0.221	0.2652	2.86	0.046	0.13156	50%
1.3	0.235	0.3055	2.9	0.06	0.174	57%
1.4	0.244	0.3416	2.93	0.074	0.21682	63%
1.5	0.246	0.369	2.95	0.084	0.2478	67%
1.6	0.244	0.3904	2.97	0.094	0.27918	72%
1.7	0.241	0.4097	2.98	0.101	0.30098	73%
1.8	0.237	0.4266	2.99	0.107	0.31993	75%
1.9	0.234	0.4446	3.01	0.113	0.34013	77%
2	0.232	0.464	3.02	0.12	0.3624	78%
2.1	0.232	0.4872	3.03	0.128	0.38784	80%
2.2	0.231	0.5082	3.04	0.135	0.4104	81%
2.3	0.231	0.5313	3.06	0.142	0.43452	82%
2.4	0.232	0.5568	3.07	0.15	0.4605	83%
2.5	0.232	0.58	3.08	0.158	0.48664	84%
2.6	0.233	0.6058	3.1	0.165	0.5115	84%
2.7	0.234	0.6318	3.11	0.173	0.53803	85%
2.8	0.232	0.6496	3.12	0.18	0.5616	86%
2.9	0.216	0.6264	3.11	0.182	0.56602	90%
3	0.229	0.687	3.12	0.183	0.57096	83%
3.1	0.238	0.7378	3.14	0.197	0.61858	84%
3.2	0.279	0.8928	3.19	0.24	0.7656	86%
3.3	0.333	1.0989	3.25	0.297	0.96525	88%
3.4	0.388	1.3192	3.31	0.35	1.1585	88%
3.5	0.435	1.5225	3.38	0.406	1.37228	90%


Will


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## Darvis (Jan 29, 2012)

Will, what can I say? Thanks for the great info!!!

That circuit you built up looks very cool, did you make the board yourself?


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## wquiles (Jan 29, 2012)

Darvis said:


> Will, what can I say? Thanks for the great info!!!


You are welcome 




Darvis said:


> That circuit you built up looks very cool, did you make the board yourself?


Yes, I worked from the Data Sheet, made my own schematic on Eagle CAD, did my own layout, ordered my own boards, the regulator, discrete parts, and soldered all of the parts myself. It is very time consuming to do all of it, but it is also fun stuff to do 

I have plenty of boards left, and I am willing to sell them if there is enough interest - either the bare board (you buy/solder everything on your own), or I can provide a completely finished board, ready to use. If you or anyone is interested, please send me email (in my signature).

Will


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## firefly99 (Sep 21, 2017)

tylernt said:


> For those of you that want to experiment with the ZXLD381, here's a way to put it on your breadboard:
> 
> First, get some breakaway header pins. These could be desoldered from an old computer motherboard (IDE/floppy connectors, USB headers, etc). Stick the long ends in your breadboard like this:
> [X] [ ] [ ]
> ...



Can't see the pictures. Kindly post again. Thanks


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## unclearty (Sep 21, 2017)

Yes...I think this should be re-opened again....now with newer, better LEDs....and all the power outages throughout the world....


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## archimedes (Sep 21, 2017)

firefly99 said:


> Can't see the pictures. Kindly post again. Thanks


The post you quoted is 6 years old, and the poster hasn't logged in to CPF in more than a year ....


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## nein166 (Sep 21, 2017)

Aw I thought there was some action on this old thread. Just another Necro... Google that one kids😁


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## firefly99 (Sep 22, 2017)

archimedes said:


> The post you quoted is 6 years old, and the poster hasn't logged in to CPF in more than a year ....





nein166 said:


> Aw I thought there was some action on this old thread. Just another Necro... Google that one kids😁


Sorry to dig up an old thread. I did google extensively on LED, Joule Thief, vampires, SMD, etc and found this & other post. Unfortunately, most of the image hosting link are no longer valid. Hence, my attempt to contact the poster about the smart way of doing some SMD.

What happen to all these posters ? 
Hope they are well.


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## archimedes (Sep 22, 2017)

When one of the major photo hosting sites recently changed their terms of service, innumerable photos were lost, across endless forums ...


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## firefly99 (Sep 22, 2017)

archimedes said:


> When one of the major photo hosting sites recently changed their terms of service, innumerable photos were lost, across endless forums ...



Because of this change, knowledge is lost. No longer available to people who are ready to learn about the subject.


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## DIWdiver (Sep 23, 2017)

Was that the library at Alexandria?


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## eh4 (Sep 25, 2017)

Does Google support image sharing? 
They seem like a well established company anyways. 

https://www.extremetech.com/mobile/...unlimited-storage-for-free-with-a-few-gotchas

https://webapps.stackexchange.com/questions/66576/can-i-use-google-for-image-hosting-on-forum-sites

"Google allows public anonymous access to images if you use absolute address of the image. One simple way to find absolute path of an image (in Google Chrome) is to right click on the image and choose "Open Image in New Tab", then you can see the absolute path of the image in the address bar of newly opened tab. You can use this address in img tags. But remember, to be able to open an image in a new tab (I'm absolutely talking about this simple method) you should not use the "Zoom" feature of Google+ photos, otherwise you have to find the absolute path of image another way (by inspecting the element containing the image in the developer panel and finding the path)"


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