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Thread: Couple of LED lights using Joule Thief circuits ...

  1. #1
    *Flashaholic* wquiles's Avatar
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    Default Couple of LED lights using Joule Thief circuits ...

    You would think that given how many flashlight projects I do that I actually own a lot of lights. Actually, I own very few lights (well, to a non-flashaholic I own an "arsenal" - but in reality I only own a few lights - most are customer lights that I photograph before sending them out to their respective owners). A couple of weeks ago we lost power here where I live and it happened right at 6AM - right when we wake up to get ready for work and take the kids to school. Still pitch black, and with no power, I scramble to get several LED lights scatered throughout the house so that we can all get ready. Problem was that I did not have that many lights to start with, so I started thinking about the "need" to make more emergency lights to keep around - specially/mostly indoors, where you only need a little bit of illumination, specially lights that can stand on their tail to light up a room, bath, kitchen, etc..

    I already had two "big" output lights: two of my own custom 1xD's, direct driving a P7, from a 3xAA adapter. But those are way, way too bright for a small room indoors, so I needed something with less output, and that would run for a LONG time as well. Since I recently have been playing with my own Joule Thief circuit, I decided to build a couple of lights to take advantage of the abundance of used AA cells and LOTS of new D cells (that come free with most D Mag's that I buy from Fry's, HomeDepot, etc.). I also though about making my own P60 drop-in with a super low output, for night adjusted vision, so I started working on these.

    First is the P60 drop-in. I bought a "kit" from Asia for the P60, so I started looking at what emiter would work well with the smooth reflector. I started with an older P4:



    But decided to use a more efficient LED instead. Looking at my parts bin revealed a neutral white XM-L, so I reflowed it into a datiLED 8mm board:



    When I tried it on the smooth reflector, I was able to get a great beam



    So I soldered and epoxied the Joule Circuit on the back:



    And tried it with a few cells:





    I soldered a wire to the spring (Bat +) that comes with the kit:





    And simply (although not "pretty) used hot glue to keep everything in place - very solid, firm setup:



    The fit of the base to the reflector in these kits is horrible, so I used a thin piece of copper tape to set the focus to the right spot in a press-fit:



    And this is how it looks in the Solar Force host:



    Home made P60 drop in:



    Nice tint:



    I can use new or used CR123 cells, but since my circuit can operate down to 0.8 volts I decided to make an adapter/sleeve so that I can also use AA cells in this host:

















    With an AA cell it was a tad shorter than an 18650 cell, but the springs more than make up for the difference:









    The next light uses some really old 3W LED's that I got many years ago, but that were vf-matched to 3.5-3.6 volts), so I decided to build a floody light using 3x of these LED's, each driven by its own Joule Thief circuit, everything feed from 3xAA cells (using another of my own custom 1xD's as a host). Since I wanted to re-use parts I already had, and I did not have any reflectors for these weird looking LED's, I decided to modify a home-made Mag D P7 reflector and make a sort of "dish" reflector out of it.

    I started with the P7 heatsink to hollow it:





    It is hard to see in this picture, but I cut a lot of "facets" in the heatsink, going from outside towards the inside, using my very sharp PCD insert to achieve a polished effect on the Aluminum:



    Then drill and chamfer the hole for the wires on both sides:







    I then did a dry fit to see how I can place the 3x "weird" emiters. Note that I had to cut/trim their wires to give me clearance:



    In this photo you can see a little bit better the facets in the heatsink - nothing too fancy but seems effective:



    I then proceeded to glue them:





    I then carefully solder the wires:



    And since this is going to be floody and very open, I put a good dose of glow in the dark powder with 2-part slow cure (30-min) epoxy:



    I then solder each of the 3x Joule Thief circuits:



    And test it:



    Here it is running:



    Ready in the host (heatsink is a press-fit):




    I carefully cut/fitted the reflector so that it would line up over the heatsink, to provide additional "focusing" on the sides:



    Here is how it looks from the front after being turned off - notice how the heatsink reflects some of the light, as well as the cut Mag reflector:



    Of course, in raw form the image is fairly "ugly", so I planned on using a diffusing film to even out things:



    Here it is OFF:



    Here it is ON:



    And although not quite focused, here is the afterglow:





    OK, now for the last "emergency" light. I already had the floody light, so I decided I wanted one with more throw. So I decided in a neutral white MC-E, using another of my own custom 1xD's as a host, so it can be driven from a single D cell or a 3xAA adapter. First, I had to once again modify the P7 heatsink in order to facilitate installing the MC-E. Fairly easy on the mill thanks to the DRO:







    I am using a left over metal reflector for P7's that I had handy:



    So I prepared everything:



    And used the reflector to position/center the LED by eye as best as I could:





    I then solder wires:



    Wired a single Joule Thief circuit:



    Prepared the stock switch:



    Here is the finished product:



    And although not in focus, here is the afterglow:




    That is for now. By the way, guess which of these 3x my kids LOVED? Of course, the weird one with the 3x LED's and the massive afterglow of the glow powder

    Will
    Last edited by wquiles; 03-28-2012 at 09:13 AM.
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  2. #2
    Unenlightened TriggerHappy's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Awesome - I love the 3 LED glowing one especially!

    Where did you get the joule thief pcbs?

    Thanks
    Pete

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    *Flashaholic* wquiles's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Quote Originally Posted by TriggerHappy View Post
    Where did you get the joule thief pcbs?
    I designed and made them myself. I still have some left but this is not a sales thread, so contact me by email (in my signature) if interested.

    Will
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Very nice. Those turned out great.

    Do you use the same components in all of your joule thief circuits regardless of which emitter is being used? Also, which power LED's perform the best?

    It's interesting to see how few components are needed to boost voltage from a 1.5V cell. I have a few cheap lights which only have a transistor and an inductor, and that's it.

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    *Flashaholic* wquiles's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Yes, same circuit. I made my own boards to use this specific Zetex part (ZXLD383):



    I can change the inductor to adjust the current setpoint, but the overall current varies with the battery supply - as the battery drains the current lowers as well, down to 0.8 volts - lower than this the circuit will not work. Right now I am using the 4.7uH to 5.6 uH size of inductors to get a fairly high current level, as the max recommended value per the data sheet is 4.7uH, but the larger the core of the inductor the less saturation at the higher current levels. Still, it is all relative - this is not a high power boost circuit

    Will
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    Unenlightened TriggerHappy's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Hi
    Thanks for posting the circuit - all the Joule Thieves I have seen have required winding a little transformer etc - that little chip makes it so much neater!

    Pete

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    Default Re: Couple of LED lights using Joule Thief circuits ...

    I'm certain you could sell alot of those circuits. I would certainly buy a few; price dependent of course!
    Great spirits have always encountered violent opposition from mediocre minds.
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    *Flashaholic* wquiles's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Quote Originally Posted by TriggerHappy View Post
    Hi
    Thanks for posting the circuit - all the Joule Thieves I have seen have required winding a little transformer etc - that little chip makes it so much neater!

    Pete
    Yup - the tradeoff is having to deal with surface mount parts, which could be a pain if you don't have experience with them. Pretty much everything I do is surface mount now-a-days, so it is not too bad once you have boards made.


    Quote Originally Posted by jabe1 View Post
    I'm certain you could sell alot of those circuits. I would certainly buy a few; price dependent of course!
    If there were enough interest I could start a proper sales thread. Email me if interested.

    Will
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Those pcb's look good Will. What diameter are they, they look very close to a AA battery?

    DatiLED made and sold some JouleTheifs a while back and they didn't last long, I am sure you could sell many of these boards.

    Cheers,
    Nova

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    *Flashaholic* wquiles's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Quote Originally Posted by ^^Nova^^ View Post
    Those pcb's look good Will. What diameter are they, they look very close to a AA battery?

    DatiLED made and sold some JouleTheifs a while back and they didn't last long, I am sure you could sell many of these boards.

    Cheers,
    Nova

    Thanks. I got enough emails to justify opening a formal sales thread for these. As to size and other details, I put all of that in the sales thread.

    For now we can keep this thread focused on lights/projects that use these circuit boards.



    Admins - I am linking to the sales thread - I hope it is allowed/permitted: Link to sales thread



    Will
    Last edited by wquiles; 03-29-2012 at 09:20 PM.
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    Moderator Kestrel's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    I'm very interested in trying a P60 joule thief with 2xAA in a three-cell SF body. Taking an excerpt of the data you posted in the 'hurricane lamp' thread:
    • Vin = 1.0v, Iout = 0.016A, eff = 27%
    • Vin = 2.0v, Iout = 0.120A, eff = 78%
    Therefore, using two depleted AA's rather than one will be an excellent configuration IMO. There seems to be a lot of potential here. I love doing this kind of stuff with my C3's.

    Edit: The above data is outdated, see Will's post below.
    Last edited by Kestrel; 04-04-2012 at 03:34 PM.
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    *Flashaholic* wquiles's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Kestrel,

    Yes, the 2xAA configuration (or 2x D in a Mag 2D body) is awesome. I took one of my 4x CR123 bodies and used to of my home-made AA to 18650 cells and built a 2xAA equivalent, and it works great.

    The only thing to note is that those higher current levels were achieved with those HUGE inductors I used in my first evaluation since that was what I was able to get my hands on. Unfortunately wiring those large inductors is a royal pain and on top of that using the large inductors leave you very little room for a P60 module, so I am now using the surface mount inductors which give me a little bit less current.



    With the much smaller surface mount 4uH inductors I am now using I am getting about 50-60mA at 1.5volts and 100-120mA at 3.0 volts, which is still very decent/effective in sucking whatever life is left out of primary cells

    Will
    Last edited by wquiles; 04-04-2012 at 02:38 PM.
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Quote Originally Posted by wquiles View Post
    [...] With the much smaller surface mount 4uH inductors I am now using I am getting about 50-60mA at 1.5volts and 100-120mA at 3.0 volts, which is still very decent/effective in sucking whatever life is left out of primary cells.
    Ah, good, thanks for the clarification.
    In the past we have had a light which flickered, in the present we have a light which flames, and in the future there will be a light which shines over all the land and sea.
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Will...

    You truly possess some mad skills my man!!!

    I have to admit, I'm super jealous of the whole machining aspect you bring to the table whilst I'm relegated to plumbing parts and tupperware for my lights...

    This is great stuff!

    BTW, the AVR programming is a hoot!! A few days into it and I've gotten all kinds of blinking LED madness going on here... which brings me to a question for you: I see Atmel sells some chips that have boost circuits built in, have you played with these and the PWM outputs? I wonder if they can be JT-ish if programmed right?

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    *Flashaholic* wquiles's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Thank you

    Glad to hear you are enjoying the AVR stuff. It is very neat to be able to get things working fairly quickly - it is a great platform. I have not seen the Atmel chip you mention, but would love to take a look. Got a link/URL?
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    I was looking at the Attiny25v, but misread the min voltage requirement to be .8v when instead it's 1.8v... too many late night learning sessions on the net for me!!

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    *Flashaholic* wquiles's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    This was completed recently by Drywolf


    Quote Originally Posted by Drywolf View Post
    Hey Will,
    Got my package today. Very professional. I'll post a pic or two of my completed thief later today.






    3 x Nichia NSDW570GS in parallel, one driver and two x AA in parallel.
    Thanks,
    Frank



    .

    I really like that!


    Will
    Last edited by wquiles; 04-11-2012 at 12:14 PM.
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    *Flashaholic* wquiles's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    By the way, I am planning on perhaps offering a "kit" for the next wave of boards, so that folks can have a "project" - perhaps something like a "father and son" (or daughter!) Saturday project. Or perhaps something that could/would be a good project for boy scouts, for camping, etc..

    Will
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Quote Originally Posted by wquiles View Post
    [...] perhaps something like a "father and son" (or daughter!) Saturday project. Or perhaps something that could/would be a good project for boy scouts, for camping, etc..
    Hi Dad!
    In the past we have had a light which flickered, in the present we have a light which flames, and in the future there will be a light which shines over all the land and sea.
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    Flashaholic sassaquin's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Quote Originally Posted by wquiles View Post
    By the way, I am planning on perhaps offering a "kit" for the next wave of boards, so that folks can have a "project" - perhaps something like a "father and son" (or daughter!) Saturday project. Or perhaps something that could/would be a good project for boy scouts, for camping, etc..

    Will
    I am very interested in a kit.

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    Thread Killer Illum's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Quote Originally Posted by TriggerHappy View Post
    Hi
    Thanks for posting the circuit - all the Joule Thieves I have seen have required winding a little transformer etc - that little chip makes it so much neater!

    Pete
    well, you could work around the flyback it by using two discrete transistors for switching and an inductor.
    My "Joule thief's" have always wind up looking like this:


    Even with thru-hole parts this one is about the size of a dime


    They're fun to make... but gee, operating LEDs beyond the 5mm arena is something I never considered, mainly because it is simply not cost effective.

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    *Flashaholic* wquiles's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Those are very cool!

    The discrete version of the circuit is a great project indeed. If folks search for "Joule Thief circuits" you will find plenty of examples

    Will
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    *Flashaholic* wquiles's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Quote Originally Posted by sassaquin View Post
    I am very interested in a kit.
    As soon as I get the new boards (about 2 more weeks is my guess at this point), I will discuss various kit ideas

    Will
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    Thread Killer Illum's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    the ZXLD chips looks more professional though, discrete transistors strain the height limit of your driver bay and it could be tempermental if your enclosure is metal.

    A couple threads to start those off who wants to diy, the schematic of my little dingy is on post 17: http://www.candlepowerforums.com/vb/...-alkaline-cell
    http://www.candlepowerforums.com/vb/...IY-1.5v-Driver

    Just like you wquiles, DatiLED made a couple of these SMT driver boards too:
    Incredibly, he used the winded coils: http://www.candlepowerforums.com/vb/...attery-drainer

    Is the XML really that efficient at ~100ma? I want to give it a try. 5mms are fun but difficult to collimate. Your spot looked pretty good!
    Last edited by Illum; 04-11-2012 at 10:27 PM.

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    *Flashaholic* wquiles's Avatar
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    Default Re: Couple of LED lights using Joule Thief circuits ...

    Excellent - thanks much for the links


    Quote Originally Posted by Illum View Post
    Is the XML really that efficient at ~100ma?
    Yes, the XML, and similar high power LED's are most efficient (lumens per watt) at very low currents. The XML in particular is most efficient in the range of 100-200mA. If you go to this thread you can see the actual experiments/measurements

    Will
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    *Flashaholic* fyrstormer's Avatar
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    Default Re: Joule Thief Circuit boards for sale ...

    Are the V2 boards large enough to serve as the anode board on the back of a P60 drop-in? The V1 boards were much too small for that, though they did fit inside a P60 drop-in rather nicely.

  27. #27
    *Flashaholic* wquiles's Avatar
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    Default Re: Joule Thief Circuit boards for sale ...

    Quote Originally Posted by fyrstormer View Post
    Are the V2 boards large enough to serve as the anode board on the back of a P60 drop-in? The V1 boards were much too small for that, though they did fit inside a P60 drop-in rather nicely.
    Not large enough. My V2 boards are about 13.2mm, and the the boards that fit on the bottom of a P60 drop-in need to be 17mm diameter. I have toyed with the idea of making a larger V3 board precisely so that it can be used directly with a P60 drop-in, but of course I would have to have enough interest to justify making another production variant to recover the investment (or at the very least try to break even!).

    Will
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  28. #28

    Default Re: Joule Thief Circuit boards for sale ...

    Soldering in a proper size washer, or some similar solution on the V2 should do the trick for P60's!

    BTW... thanks for the answer, Will. Figured I was missing something.
    I'm an excellent driver. Of course I don't have my underwear... I'm definitely not wearing my underwear

  29. #29
    *Flashaholic* wquiles's Avatar
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    Default Re: Joule Thief Circuit boards for sale ...

    No worries man. Please do post some pictures of the project(s)

    Will
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    Default Re: Joule Thief Circuit boards for sale ...

    Quote Originally Posted by wquiles View Post
    Not large enough. My V2 boards are about 13.2mm, and the the boards that fit on the bottom of a P60 drop-in need to be 17mm diameter. I have toyed with the idea of making a larger V3 board precisely so that it can be used directly with a P60 drop-in, but of course I would have to have enough interest to justify making another production variant to recover the investment (or at the very least try to break even!).

    Will
    It would be a nice option. I'd be up for at least two more boards big enough to serve as combo anode+driver boards for P60 drop-ins. It wouldn't be an issue if I could find suitable anode boards anywhere, but for whatever reason they're hiding from me, and I'd really like a clean solution.

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