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Author Topic: Joule Thief  (Read 6276465 times)

TinselKoala

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Re: Joule Thief
« Reply #16845 on: January 26, 2015, 09:46:56 PM »
TinselKoala
here you have a few interesting Vids that show some interesting effects
as a builder yourself ,would you explain this acceleration in the second video
to some of our builders here working on acceleration effects and voltage increases


I know the second Vid [with the motor ] has other "snake oil" purposes ,but you also are showing acceleration under load,
it would be good to discuss this here,I know other builders respect your work.

 Voltage  https://www.youtube.com/watch?v=FLsOCYPCvGc


acceleration  https://www.youtube.com/watch?v=9x2YfA9LU5s


When you have time and in the appropriate Thread ??


respectfully


Chet

The first linked video should be labelled "Current" rather than "voltage", since I am measuring the voltage drop across an inline current-viewing resistor to show the fact that the _current_ draw from the battery source is the same or slightly less with the 24 LED load _connected_  than it is with the load disconnected. This is a real effect and should be replicable by anyone with a similar JT. And, indeed, the video was done in response to some "oohing and ahhing" over the same "amazing" effect posted in another thread by a different poster using a different circuit (but the same operating principle). However, current is not power, power is not energy, and a real measured estimate of the input and output  _power_  should be done by the usual, correct means, before any conclusions may be confidently drawn.

The second video's acceleration effect _may_ be an artifact caused by the inadequate "measurement" of the quantities concerned. All kinds of strange things can happen when you are in the near-field of a relatively powerful source of EM radiation (inside the black box), and improper measurements can lead one to make improper conclusions.  As Richard Feynman may have said, "The easiest person to fool is yourself."

Groundloop

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Re: Joule Thief
« Reply #16846 on: January 26, 2015, 09:47:13 PM »
Hi,

Can anyone help me with a answer to this question?

Regards,
GL.

MarkE

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Re: Joule Thief
« Reply #16847 on: January 26, 2015, 09:55:47 PM »
Hi,

Can anyone help me with a answer to this question?

Regards,
GL.
Your inductance meter measures the amount of voltage it takes at a test frequency to drive a reference current through the winding.  The second winding has a high mutual inductance with the first winding as it is wrapped around the same toroid.  But wrapped as it is around the second toroid, it has a lot of uncoupled inductance.  So:  Closing the switch makes the measured inductance go down, but not as much as if the second coil did not also wrap around the second toroid.

Groundloop

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Re: Joule Thief
« Reply #16848 on: January 26, 2015, 10:02:54 PM »
Your inductance meter measures the amount of voltage it takes at a test frequency to drive a reference current through the winding.  The second winding has a high mutual inductance with the first winding as it is wrapped around the same toroid.  But wrapped as it is around the second toroid, it has a lot of uncoupled inductance.  So:  Closing the switch makes the measured inductance go down, but not as much as if the second coil did not also wrap around the second toroid.

MarkE,

Thanks, I have set up a test and the readout on the L meter did go down to almost half when the switch was closed.
This confirms that it is possible to use this method to tune a oscillator to two different frequencies just by open or
close a switch.

Thanks again.
GL.

TinselKoala

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Re: Joule Thief
« Reply #16849 on: January 26, 2015, 10:18:52 PM »
Hi,

Can anyone help me with a answer to this question?

Regards,
GL.

I used the same numbers of turns as on your diagram:

TinselKoala

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Re: Joule Thief
« Reply #16850 on: January 26, 2015, 10:21:22 PM »
MarkE,

Thanks, I have set up a test and the readout on the L meter did go down to almost half when the switch was closed.
This confirms that it is possible to use this method to tune a oscillator to two different frequencies just by open or
close a switch.

Thanks again.
GL.
You can also do it with a single inductor, using your switch to short across turns, or by selecting multiple taps on the inductor.


Groundloop

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Re: Joule Thief
« Reply #16851 on: January 26, 2015, 11:01:53 PM »
You can also do it with a single inductor, using your switch to short across turns, or by selecting multiple taps on the inductor.

TK,

Thanks for the test. Yes, I have seen this coil switching in "old" HF power amplifiers. :-)

GL.

synchro1

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Re: Joule Thief
« Reply #16852 on: January 27, 2015, 12:07:47 AM »
It is a reasonable guess that the "high voltage" is something he measures when the LEDs are not connected.  It is also a reasonable guess that it is less than 50V peak, which is certainly much greater than the three volts required to run a white LED.

@MarkE,

Quote from Pirate88179:

"I am even using some commercial bulbs in my lights, like the Lights of America 24 chip led bulbs and ...they are just fine with 400 volts at high freq.  My bedside table uses 2 of those bulbs and...I have been using it every night for many years and...the bulbs still work. (still using the original D cell battery also)".

Pirate's running a 120 volt AC LED bulb at 400 volts.

MarkE

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Re: Joule Thief
« Reply #16853 on: January 27, 2015, 01:27:31 AM »
@MarkE,

Quote from Pirate88179:

"I am even using some commercial bulbs in my lights, like the Lights of America 24 chip led bulbs and ...they are just fine with 400 volts at high freq.  My bedside table uses 2 of those bulbs and...I have been using it every night for many years and...the bulbs still work. (still using the original D cell battery also)".

Pirate's running a 120 volt AC LED bulb at 400 volts.

That's not something that I would do.  The electronics in a 120V LED won't be very happy seeing 400V.  His 400V may be open circuit.  Without seeing a sample of his measurements and how he performs them, I don't know what he's really doing.

Pirate88179

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Re: Joule Thief
« Reply #16854 on: January 27, 2015, 01:49:16 AM »
@MarkE,

Quote from Pirate88179:

"I am even using some commercial bulbs in my lights, like the Lights of America 24 chip led bulbs and ...they are just fine with 400 volts at high freq.  My bedside table uses 2 of those bulbs and...I have been using it every night for many years and...the bulbs still work. (still using the original D cell battery also)".

Pirate's running a 120 volt AC LED bulb at 400 volts.


That is correct.  You can screw those bulbs into a light fixture and run them on 120, or place into my circuit and run them at around 400.  The lights of America have no electronics inside, so no need to modify.  Most of them are 27 chip leds and I have some that are 24.  Now, when I use the Cree 40 watt equiv. bulbs in the same circuit, I have already removed all of the electronics and am just using the leds.  I have hundreds and hundreds of hours on those LOA bulbs and all of them still work great.  Much brighter than lighting a gutted cfl.

Even running 2 bulbs of the LOA style led bulbs with 27 chips each (Like the one next to my bed) I am only drawing 150 mA's.

Bill

MarkE

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Re: Joule Thief
« Reply #16855 on: January 27, 2015, 03:16:34 AM »
That is correct.  You can screw those bulbs into a light fixture and run them on 120, or place into my circuit and run them at around 400.  The lights of America have no electronics inside, so no need to modify.  Most of them are 27 chip leds and I have some that are 24.  Now, when I use the Cree 40 watt equiv. bulbs in the same circuit, I have already removed all of the electronics and am just using the leds.  I have hundreds and hundreds of hours on those LOA bulbs and all of them still work great.  Much brighter than lighting a gutted cfl.

Even running 2 bulbs of the LOA style led bulbs with 27 chips each (Like the one next to my bed) I am only drawing 150 mA's.

Bill
OK so you've got a series string of LEDs without any current limit resistors, or with one or more current limiting resistors?  These are nominally 3V white LEDs?  And the 150mA draw is from a single D cell?  Do you have any oscilloscope captures of the LED drive waveform?

Pirate88179

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Re: Joule Thief
« Reply #16856 on: January 27, 2015, 04:04:50 AM »
OK so you've got a series string of LEDs without any current limit resistors, or with one or more current limiting resistors?  These are nominally 3V white LEDs?  And the 150mA draw is from a single D cell?  Do you have any oscilloscope captures of the LED drive waveform?

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.

Pirate88179

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Re: Joule Thief
« Reply #16857 on: January 27, 2015, 04:09:01 AM »
Mark:

Also, the driver is nothing more than a modified flash camera circuit.  I bought about 90 of them surplus for like $.40 ea.

Bill

PS This photo matches most of my bulbs.

synchro1

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Re: Joule Thief
« Reply #16858 on: January 27, 2015, 05:33:31 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.

MarkE

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Re: Joule Thief
« Reply #16859 on: January 27, 2015, 06:43:31 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.
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.