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

[notrefined]

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

 

[Cypher_Aod]

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.

 

[Darvis]

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...

 

[Darvis]

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.

 

[Cypher_Aod]

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

 

[Justin Case]

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.

 

[Justin Case]

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.

 

[IcantC]

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?

 

[Darvis]

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.

 

[IcantC]

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.

 

[notrefined]

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?

 

[Darvis]

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.

 

[potpot]

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

 

[cnjl3]

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!

 

[datiLED]

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.

 

[tylernt]

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?

 

[datiLED]

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.

 

[wquiles]

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?

 

[Justin Case]

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.

 

[tylernt]

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?