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Author Topic: Joule Thief  (Read 5815744 times)

Offline MarkE

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Re: Joule Thief
« Reply #16860 on: January 27, 2015, 06:44:17 AM »
No resistors or anything else in these bulbs.  The amp draw was tested from an AA battery, but I use a D cell in my reading light so it lasts longer.  So far, I have not had to change it.  I don't know how the chips in the LOA bulbs are wired...probably series but I can not confirm that.  No scope shots of the circuit as I was told several years ago that the high voltage could damage my Tektronix 2213.  I am not good with my scope so I played it safe.

TK has one of these circuits that I sent him, we could ask him if this can be safely scoped.  All I know is that I bought about 8 of these lamps 4-5 years ago and all of them are still working great.  I also made lights for my daughter, and some of my friends and all is still well with them too.

Bill

PS  I see that this is an old photo I had on file.  All of my bulbs have a standard Edison base, but this gives you an idea of what they look like.
TK has a 100X probe.  He can safely look at this circuit.

Offline TinselKoala

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Re: Joule Thief
« Reply #16861 on: January 27, 2015, 10:19:07 AM »
Is it the modified flash camera circuit? Yes, I installed that one in a jar with a gutted CFL tube, it works quite well with that. I call it the "Pirate Light". I'll dig it out and scope it, probably have to wait till tomorrow though. I'm bushed from working on something else. Unfortunately I don't have an equivalent LED bulb to try it on.

I have a failed Cree LED bulb that I haven't taken apart yet to see why it failed. Only got 30 or so hours out of that one, a 18 Watt 1600 Lumens unit that I was running in the overhead fixture on the normal mains supply. I liked the bright light from it, but it sure didn't last very long. I actually don't know how to take it apart without messing it up, anyone have any ideas?

Offline synchro1

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Re: Joule Thief
« Reply #16862 on: January 27, 2015, 10:57:02 PM »
It doesn't work that way.  The I2R losses per bulb go down dramatically when adding bulbs, but then the number of bulbs wasting energy in their individual I2R goes up.  Unless one starts at a point where they are kicking the snot out of LED to begin with, the efficiency gains had by paralleling more LEDs quickly hit diminishing returns.

@MarkE,

Yor're just shooting it out your ass. A few comments back you were confused into imagining we were taking about 3V LEDS; Now you pretend you know more then me after months of testing and half a dozen videos. You grow despised as an ignorant "Know it All". Wise up to yourself Bub!

Offline Pirate88179

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Re: Joule Thief
« Reply #16863 on: January 28, 2015, 01:38:42 AM »
@Pirate88179,

That's beautiful. I broke one of those bulbs and examined the circuit at the base. There're several standard componants, capaciitors inductors etc. I'm sure it rectifies to DC. My tests confirmed that additional bulbs generate light more efficiently. Adding two additional bulbs would probably deliver the same amount of light for 100 ma instead of 150 based on a savings factor of 17% per additional bulb.

We must be talking about different bulbs.  I have not purchased any of them in a few years, so maybe they have changed but, I completely took apart my first one as I assumed there was some circuitry in there...nope.  Just two wires connecting the leds to the Edison base.  No resistor, nothing.  That is why I was suggesting folks to use them back then as no mods were needed.

Bill

Offline Pirate88179

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Re: Joule Thief
« Reply #16864 on: January 28, 2015, 01:46:12 AM »
Is it the modified flash camera circuit? Yes, I installed that one in a jar with a gutted CFL tube, it works quite well with that. I call it the "Pirate Light". I'll dig it out and scope it, probably have to wait till tomorrow though. I'm bushed from working on something else. Unfortunately I don't have an equivalent LED bulb to try it on.

I have a failed Cree LED bulb that I haven't taken apart yet to see why it failed. Only got 30 or so hours out of that one, a 18 Watt 1600 Lumens unit that I was running in the overhead fixture on the normal mains supply. I liked the bright light from it, but it sure didn't last very long. I actually don't know how to take it apart without messing it up, anyone have any ideas?

Yes, the flash camera circuit...scoping that would be great.  (Try not to get zapped again, ha ha.)

Is your cree anything like the 800 lumen 60 watt equiv. that you have seen me use in some videos?  Glass globe, heat sink ring and plastic base going down to the base?

If it is, I can tell you how to do this easily.  (Well, it was easy for me after I broke the plastic and saw what was inside)

Here are some photos to see if they are made similar.

Bill

Offline TinselKoala

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Re: Joule Thief
« Reply #16865 on: January 28, 2015, 02:21:24 AM »
Yes, it's similar, and I already took it apart... by breaking the glass accidentally! Once I did that the rest was easy, some snaps and pressfit stuff. I can't get any of the LEDs to light up by any means, I even melted one off the heatsink mount and tried just the bare LED. I can't imagine that all 20 of the the LEDs are blown somehow but that is how it is acting, so I've just tossed it into the junkbox

Offline Pirate88179

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Re: Joule Thief
« Reply #16866 on: January 28, 2015, 02:35:45 AM »
Yes, it's similar, and I already took it apart... by breaking the glass accidentally! Once I did that the rest was easy, some snaps and pressfit stuff. I can't get any of the LEDs to light up by any means, I even melted one off the heatsink mount and tried just the bare LED. I can't imagine that all 20 of the the LEDs are blown somehow but that is how it is acting, so I've just tossed it into the junkbox

Mine have three snap clips that you can't see but, you can feel them with a jewelers screwdriver.  You just pop around under the heat sink until you release all three.  Then you can snap it back together.

Did yours have a complicated driver board like this inside?  Maybe something on the board is fried?  Oh, I see you said you tried lighting the leds directly...never mind.  When I run my bulbs on the mains, they get pretty hot, which is why I added a much larger heat sink.  All of my bulbs still work.  I gutted three of them for my lighting projects but use the others on the mains.  I also peel that diffusion goop off of the bulbs on all of them.  The bulbs are not clear and still diffuse and I figure more light can get out that way.

Bill

Offline Pirate88179

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Re: Joule Thief
« Reply #16867 on: January 29, 2015, 03:35:33 AM »
I just wanted to add that the circuit I sent TK was a Kodak style circuit modification and the ones we were making here way back when were based on the AA Fuji design.  Someone tested the modified Fuji a while back and said it was about 400 volts.  The Kodak based circuit may have less output as my lights are not as bright as the ones I still have running the Fuji.

If I had to make a guess, I would say the new style Kodak based circuits are probably about 300-325?  Just a guess. 

Now, the Jeanna circuit using the large toroid (3 3/8" dia.) were measured (not by me) to be over 800 volts on a single, "dead" AA battery.  The zaps I have received from that circuit hurt much more than any of the camera circuits that have bitten me.

Bill

Offline PhiChaser

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Re: Joule Thief
« Reply #16868 on: January 29, 2015, 04:11:57 AM »
Hell of a 'light bulb'...
And this is 'going green'...
Goddam scary if you ask me.

Offline sm0ky2

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Re: Joule Thief
« Reply #16869 on: March 06, 2015, 01:41:07 AM »
@PhiChaser

you forgot to label the built-in self-destruct mechanism, that keeps us buying more of these things!!

Offline Pirate88179

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Re: Joule Thief
« Reply #16870 on: February 18, 2016, 05:01:03 AM »
@PhiChaser

you forgot to label the built-in self-destruct mechanism, that keeps us buying more of these things!!

I actually have one of my Cree bulbs (unmodded and running off mains) beginning to flash a bit.  I suppose this means that the driver board is on the way out.  If it gets too annoying or burns out totally, I guess I will just run it off a flash circuit like I do the others.

The weird thing is that this bulb has been run with my added heat sink since almost day one.  I suppose that driver board was not meant to last forever.
Still, this was way longer than any cfl I ever had.  Also, none of the Cree bulbs have burst into flames (yet anyway) like several of my cfl's did back a few years ago.

Bill

Offline MileHigh

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Re: Joule Thief
« Reply #16871 on: February 18, 2016, 05:48:48 AM »
So many devices run off of low-voltage DC these days that all of these wall-warts become a pain.  They are shoving a form of wall-wart into an LED light bulb so it works in a standard socket.

Then you have homes with solar panels and battery banks that work off off DC, so this whole DC to AC back to DC is a pain in the butt and more expensive and less reliable.

I hope the consumer electronics industry and the housing industry is working in the background to solve this problem.  They need to launch some kind of universal home "smart DC power distribution bus" with new wall sockets and plugs just for DC power.   You need "smart DC power plugs" for electronics and "smart DC power wall sockets" in houses.  Sort of like a USB 3.1 for DC power where when you plug your DC device into the DC wall socket, there is a negotiation phase that takes place so it is transparent if the device requires 5 volts or 12 volts, etc.

Offline Pirate88179

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Re: Joule Thief
« Reply #16872 on: February 18, 2016, 05:59:10 AM »
So many devices run off of low-voltage DC these days that all of these wall-warts become a pain.  They are shoving a form of wall-wart into an LED light bulb so it works in a standard socket.

Then you have homes with solar panels and battery banks that work off off DC, so this whole DC to AC back to DC is a pain in the butt and more expensive and less reliable.

I hope the consumer electronics industry and the housing industry is working in the background to solve this problem.  They need to launch some kind of universal home "smart DC power distribution bus" with new wall sockets and plugs just for DC power.   You need "smart DC power plugs" for electronics and "smart DC power wall sockets" in houses.  Sort of like a USB 3.1 for DC power where when you plug your DC device into the DC wall socket, there is a negotiation phase that takes place so it is transparent if the device requires 5 volts or 12 volts, etc.

That's a great idea.  The power company can just split off a dc (hopefully clean) bus that can run all of this dc stuff we now use.  Or, we can just find an efficient way to make our own dc at our homes...not to run our homes, but just to run all of our dc devices.

Hey, I ran across this old video from Lidmotor from a few years back about his resonant JT circuit: https://www.youtube.com/watch?v=850LpSRkL-A

Have you seen that one?  It makes for a very efficient JT it seems, unless something else is going on with his circuit design.  Obviously this is far different from what we would call a "standard" JT circuit but after reading some of the discussions on the other topic, I thought it was interesting.

Bill

Offline crowclaw

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Re: Joule Thief
« Reply #16873 on: February 18, 2016, 09:25:58 AM »
We are seeing more AC power point mains outlets available with single or twin USB sockets incorporated...good idea. No doubt you guys over the pond have them also?

By the way how are you Bill haven't looked in for a while.

Offline MileHigh

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Re: Joule Thief
« Reply #16874 on: February 18, 2016, 12:39:43 PM »
Here is a Joule Thief issue that has been in the back of my mind for a long time.  See the attached portion of a Magluvin scope capture of his Joule Thief collector-emitter voltage.  Of course the collector-emitter voltage is the voltage across the LED.  Naturally there is an unknown current waveform associated with the voltage waveform that will have a similar decaying waveform shape.

So the issue is this:  You can clearly see the declining voltage across the LED.  So how bright is the LED as a function of the voltage?  What if the LED is bright for the upper half and very dim for the lower half?  I don't know if this is true but it merits an investigation.

If if the lower half light output from the LED is very dim then presumably it does not contribute to the visible light output of the LED to the naked eye and there is a lot of "wasted energy" in the inductor discharge.  If that's true it is arguably an "issue" and it suggests you can build a better mousetrap Joule Thief.

So, what if, for the sake of argument, that half of the energy in the coil discharge is essentially wasted because it barely lights the LED?

MileHigh