Couple of LED lights using Joule Thief circuits ...

[Illum]

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.

 

[wquiles]

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

 

[wquiles]

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

 

[Illum]

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...t-to-power-a-5-mm-LED-from-1.5V-alkaline-cell
http://www.candlepowerforums.com/vb/showthread.php?226903-ZXLD381-3Cuts-DIY-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/showthread.php?279042-5mm-LED-battery-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!

 

[wquiles]

Excellent - thanks much for the links

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

 

[fyrstormer]

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.

 

[wquiles]

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.

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

 

[Bimmerboy]

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.

 

[wquiles]

Re: Joule Thief Circuit boards for sale ...

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

Will

 

[fyrstormer]

Re: Joule Thief Circuit boards for sale ...

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.

 

[wquiles]

Re: Joule Thief Circuit boards for sale ...

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.

I know the "blank" boards are available (somebody is of course making them!), but I have not tried to find them myself so I don't know where to start if I were looking to get some.

As to the 17mm version of the Joule Thief - I would have to have both in stock, as the smaller size is good for AA/CR123 lights/small projects, etc..

I will definitely keep it under consideration (never say never, right?), but I need to make 100+ production boards to get "reasonable" costs , so I don't want to be stuck with 98 boards nobody else wants

Will

 

[fyrstormer]

Re: Joule Thief Circuit boards for sale ...

I know I can remove components from another driver board, but that seems awfully wasteful. I'd really rather not have to destroy something that would be useful otherwise.

Will, here's an idea: add a poll to this thread so people can "vote" on whether they would buy a 17mm version of the Battery Vampire driver. It wouldn't be an official pre-order, but it would at least give you a clear idea of whether there is enough demand to justify ordering the larger board.

 

[Kestrel]

I have moved this "17mm 'joule thief' board" discussion from the Joule Thief Circuit boards for sale thread to the current thread so as to keep the sale thread on-topic. Please feel free to discuss this topic here.
Thanks folks,

 

[wquiles]

Yes please! Have you made any more attempts to get these to run at a lower current suitable for a 5 mm LED?

Yes, more on this below ...

I've done a couple run time tests using both a fully charged 123 primary and 2 L91s. I get about 12 hours of useful light, starting out around 75 lumens and tapering off to less than 1. As Will said, if I let it go until I can barely see the glow of the LED anymore, I measure about .8 volts left in the cell(s).

Awesome - thanks much for actual usage data

Hey Will, got my V2 board today! Thanks!

Excellent - thanks!

It's alive!

XR-E 2800K

Very cool application :devil:

Hey Will-keep us/me posted on the possible host or turnkey options.
Besides the P60 option- I'm looking for something smaller.

Not tryin to pester u

I am trying to offer some AA options - running a little bit behind on these. I hope to have something soon


Will

 

[psychbeat]

Ooops- didn't know about this thread- thanks!

 

[wquiles]

OK, so now that I am caught-up from my sales thread on custom Delrin parts for the V10R/V11R, I have been able to spend some time on the my Joule Thief's characterization on very low currents

I started by building 6x test boards with various inductor values - here are 4x of them:

And then I tested with my normal target (3Watt Luxeon), but also with a 5mm and 3mm white LED (both 20mA rated):

My standard Joule Thief has a default inductor value of 4.7uH, so I tried inductors values of: 22uH, 33uF, 47uH, 100uF, 220uH, 470uH, and 1000uH (1mH), at voltages in between 1.5 and 3.5 volts (to simulate 1xAA, 2xAA, and 1xCR123, and a little above 3V to know some more - I am always curious like most of you!). Out of these tests today:

- for single AA cell, the 22uH gives between 14-15mA for the 5/3mm LED's, so a value of about of slightly less than 22uH will give you the 20mA, but with 22uH you have some headroom, so this is about perfect to account for part to part variability.

- for 2xAA cells, or 1x CR123 cell (3.0 volts), the 1000uH (1mH) gave 9-10mA, but at 3.4 volts (like with two Energizer Lithium AA's) I got 19mA, so it looks like 1mH is the ideal value for two AA cells (of any type), or a single CR123.

Will

 

[wquiles]

OK guys, this is the first kit that I had in mind - something really simple to get started with a Battery Vampire (Joule Thief) circuit:

It is a 2xAA kit, driving a 3mm white LED, and using a V2 circuit board with a 1mH inductor to keep the current to the LED at just under 20mA with fresh cells, but that will keep sucking the life out of the AA cells for a long time:

On the inside, I made everything super simple to do:

All I need here is a drop of epoxy to keep everything in place for long term stability (in case it gets dropped, etc.):

Since this battery carrier even has a built-in clip, it can act as a marker, hang from a tent while camping, in your pocket (of wife's purse) for EDC duty, etc..

Is there is enough interest in these, I can do a step-by-step short tutorial, and I can see what type of pricing I can get on the components (not that many) to make it an attractive project.

Interested?

Will

 

[psychbeat]

Would a Nichia 219 or xpg fit in there?

or are you thinking of offering anything smaller or metal?

I'm semi clumsy @soldering but could probably manage one of these

 

[wquiles]

Would a Nichia 219 or xpg fit in there?

or are you thinking of offering anything smaller or metal?

I'm semi clumsy @soldering but could probably manage one of these

This particular kit can't be all things to all people, so the 3mm LED fits the original intent of something simple and low cost. Given the extremely low power, there is no advantage on a metal case for this particular project. For folks who are interested in the kit but don't want to mess with doing/completing the kit themselves, I will be also offer turn-key kits, but of course those will be higher priced to cover my hand assembly labor charges.

With enough time and money you can fit anything anywhere, so yes, if you modify/cut this battery carrier I am sure there is a way to fit a Nichia 219 or XP-G in there somehow, but now you got more cost and labor on the project. With a Nichia 219/XP-G (or any 3W+ LED) you would not need the low-power version of my V2 board with the 1mH inductor, but if you are after longer runtimes, then of course you could use this low current version of the V2 driver to power the higher power LED's at the same very low currents of the 3mm LED.

Will

 

[^^Nova^^]

Hi Will,

One of these for 2xAA with a 5mm as a kit would be wonderful. What 5mm led options do you have? IIRC you said something about some CREE ones you had?

These should run for ages and still suck the last juice out of AA's and the holder is great.

Cheers,
Nova