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Author Topic: 25mV Joule Thief powered by peltier merely using our body heat -Free energy 24/7  (Read 227071 times)

Offline magpwr

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Hi Acmefixer,

It's a good question how i came to find 2SK170 to be the best.

There was this crazy experiment i was doing with same toroid used for my 45mV joule thief which i was using Japanese transistor 2SD1450 but it not the self starting version,as shown in youtube "sanjev21".

I did a lot of research and found that mosfet can never be used in joule thief,because it do not release immediately(in ms or ns) after switching on.
Althought mosfet is a "excellent switcher" if combine with microprocessor.

It was a long shot.There was youtube video whom posted about "self starting stirling engine" using peltier at the source of heat to spin motor to start engine.
It was using mosfet 2N7002 with inductor to positive.The startup voltage was laround 0.4v.

I experimented using "multisim a virtual electronic lab".The transformer in it i'm stuck with "TS_POWER_25_TO_1" (100% efficient) 25 turns:1.(The only transformer i could use for ultra low voltage joule thief)
Tried all the transistor,mosfet,fet,jfet.Then found JFET had the self starting capability.Then spent 3 days to find the best one then slowly lowered source voltage to 0.025v.

I have "9 version of ultra low voltage joule thief" virtual lab file but only 3 is worthy of mentioning as current handling for the rest is not good enough.

JFET standalone version as shown in my youtube video, better version is combining ZTX1047A or ZTX1048A with 2SK170(Since transistor got better current capability using JFET to auto kickstart transistor as well),then there is a version
which i used JFET with 2 resistor to control the current going to transistor.The problem with last version the startup voltage is little higher
 but give me "constant current draw" all the way to 2v source.

I tested with 40 over key component or components in virtual environment to derive this ideal circuit by accident.Please ignore 330Ohms resistor to diode as i placed it to allow circuit to function if provided i'm using 1000uf cap at output for 25mV input.
« Last Edit: January 23, 2013, 12:09:20 AM by magpwr »

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Offline gyulasun

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Hi Folks,

In the meantime I have done some patent search on this low voltage DC-DC converter topic and I think I found good info.

First of all I found the patent that includes the schematic Acmefixer showed in Reply #94. It is US4734658 (Low voltage driven oscillator circuit), see here:  http://www.google.com/patents/US4734658   (By the way here is a very similar circuit shown much earlier: http://www.google.com/patents/US3681674 ). Both are good reading for those wishing to get a deeper insight into very low voltage converters.

Here is another patent which includes what kind of features a FET should have ideally for such low voltage converters, see this: http://www.google.com/patents/US4015609 
So for a FET the drain-source ON resistance should approach zero, of course and the gate-source cut-off voltage (or threshold voltage for MOSFETs) should be also near to zero (so that a tiny mV amount of change in the gate-source voltage should cut the drain current off). In the patent you can see an attempt to improve BOTH characteristics of the off the shelf JFETs of that era.
To reduce the ON resistance, the inventor also paralleled some FETs. And to reduce the cut-off voltage, the inventor connected two such paralleled FET groups in series: the joined source pins of the paralleled group A is connected to the joined drain pins of the paralleled group B, while all the gates in groups A and B are joined to be a single gate point, the main drain pin is the drains from group A and the main source is the sources from group B. This way the resulting cut-off voltage is reduced below that of any such single JFET. (Of course the series connection of the groups increases the ON resistance BUT the advantage received from the lower cut-off voltage is more beneficial from the input DC supply voltage level point of view.)

So magpwr's finding the 2SK170 type and paralleling them was the correct first step to reduce the ON resistance, hence to be able to reduce the working supply voltage. And luckily, this type is characterised as having high transconductance (22mS) at 3mA drain current i.e. it has high enough gain to start oscillation at a low supply voltage and this transconductance is enhanced each time your paralleling the FETs. AND the cut-off gate-source voltage for this type is between  -0.2 to -1.5V only, the  -0.2V goes with the GR suffix and the  -1.5V goes with the V suffix, while the BR suffix is somewhere inbetween.

Now we know why the higher current switching type JFETs like J105 etc may not work  from a lower supply voltage than the 2SK170: because these JFET types inherently have -5 to -10V (or higher) gate source cut-off voltage ranges and this is a drawback in this respect. (The higher cutoff gate voltage inherently decreases transconductance.)

The following correct step was to turn to the ALD110800 and ALD110900 MOSFET types (from TinselKoala link) as these are advertised as zero-voltage-threshold MOSFETs. However their big drawback is the 104 kOHm drain-source ON resistance at the zero gate-source voltage (this huge drain-source resistance goes down to 500 Ohm when the gate-source voltage is increased to +4V from zero).  So it seems this zero voltage threshold feature cannot bring advantage in such low supply voltage converters. Of course these new MOSFET types can work very nicely in circuits where the high ON resistance is not neccessarily a drawback and can be matched.

Then I found  a patent which shows an interesting solution to reduce the JFETs relatively high ON resistance so that overall efficiency may be increased.  By the way, even if the JFETs are paralleled, they still can have rather high ON resistance, just consider the 2SK170BR, it surely have a drain-source ON resistance between 800 to 1600 Ohm at zero gate-source bias and if you parallel 4 of them, this range reduces to between  200 and 400 Ohm. So compare this to the primary coil's self impedance which is surely well under 1 Ohm at DC and probably represents a few times ten Ohm at the oscillator's frequency, it is a transformed impedance from the gate side of the fet, depends on the primary/secondary turns ratio too.)

While some circuits use bipolar transistors connected in parallel (as a second switch) with the jfet or MOSFET (this is discussed here: http://www.google.com/patents/US4322724 ) but here in this patent a MOSFET is used in parallel with the jfet, see here Fig.3: http://www.google.com/patents/US7170762 

All in all, what I deduce from all these patents info, including the work of magpwr, acmefixer, conradelektro and scratchrobot,  I think you need to use at least 1:80 to 1:100 or even higher turns ratio, you may need to use resonance at the secondary coil of the transformer (see the tuning capacitors at the secondary coil: http://www.linear.com/product/LTC3108   and you can combine either low saturation bipolar transistors or MOSFEts in parallel with the 2SK170 jfet as a second switch, controlling this latter together with the jfet from the up-transformed input voltage. If you have a logic level MOSFET that can fully conduct at say 1V gate-source voltage, and you have (say) 1:100 turns ratio, then 10mV across the primary coil will insure operation of the MOSFET in theory BUT to have 10mV voltage drop across the primary coil, the voltage drop across your jfet defines input sensitivity because the full input voltage gets divided between the primary coil and the jfet's ON resistance. So paralleling the 2SK170 jfets is still needed I am afraid to self-start the oscillator from as low supply voltage as possible. Can you all agree with this?

rgds,  Gyula
« Last Edit: January 27, 2013, 10:31:37 AM by gyulasun »

Offline conradelektro

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@gyulasun

You did a very useful research. I will try to understand your conclusions by going through the many references you posted. With my bigger toroids I can do the 1:100 reatio (e.g. 5:500) with the 0.22 mm enamelled wire. Thinner wire is just to awkward to do by hand.

Just a hint, here you can look up every patent you wish to see:

http://worldwide.espacenet.com/singleLineSearch?locale=en_EP

http://worldwide.espacenet.com/advancedSearch?locale=en_EP

What I want to do, is to make a LED glow in the garden with a copper and an aluminium tube in the ground (as a basic galvanic battery). The copper and aluminium tube in the ground show a Voltage of about 400 mV, but the Voltage brakes down below 50 mV when connecting magpwr's circuit. May be at 10 mV, the tubes can supply enough current to reach the 100 µW necessary to make LED glow.

Magnesium and copper might work, but I do not like magnesium, too expensive and all sorts of side effects. I still have to do a test with a galvanised steel tube and a copper tube, but at the moment everything is frozen solid in the garden under 0.2 meters of snow.

That's why I play with snow and a Peltier Element (see the attached photos). The little saucer is tin, the big mortar (cup) underneath is brass.

Greetings, Conrad

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Offline gyulasun

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...
 With my bigger toroids I can do the 1:100 reatio (e.g. 5:500) with the 0.22 mm enamelled wire. Thinner wire is just to awkward to do by hand.

...

Hi Conrad,

Thanks and may I suggest to make taps on the secondary coil at  1:50 and 1:75  turns ratio to make matching more flexible. Also, you could consider using ferrite pot cores or normal ferrite E cores instead of the toroid core shape, these latter cores are much easier to wind.

rgds, Gyula

Offline magpwr

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hi conradelektro,

In theory maybe moving the rods closer to each other would reduce the resistance or internal- resistance(In the case of battery) for your garden battery.

It reminded me of a crazy experiment done around 15 years ago using zinc/carbon battery case after removing all the black stuff in battery.
I actually stuffed fertilizer in it which did not work well.Then i added little water with fertilizer to make it moist and throw mix back into battery case.
I then charged with around 7.5v to battery for 2min.I then placed the battery into a mechanical movement clock design to work on 1xAA battery.
The clock actually worked for few days then "fertilizer AA battery" died.
 
hi gyulasum,

Thanks for providing some interesting links.It does help us to promote creativity in each of us.I never knew people actually patent ultra low voltage voltage booster.
Good thing mine is unique and i will never patent my design especially for simple "electronics".It would be a waste of effort or time maybe money to patent.

---------


I would be planning to work on this project to compliment my 25mV joule thief.It's using radio wave to charge battery.I will be using it with ultra-caps.
http://www.youtube.com/watch?v=tjxldE8JsDw

I was active in this forum where there was discussion on the "RF diode charger" and etc.
http://laserhacker.com/forum/index.php?topic=104.0

I noticed it's very difficult to find antique items in my country like 1N34A that i have to order online from ebay.
I had problems even finding small copper tubes normally used in Air-con smaller version for copper tube\toroid transformer to experiment on resonance as i mentioned earlier in this forum.

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Offline conradelektro

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@gyulasum:

I got this core http://at.farnell.com/ferroxcube/etd49-25-16-3c90/ferrite-core-half-etd49-3c90/dp/3056417?Ntt=3056417 (two halves, bobbin and clips). Would this be any good to wind the 5:500 coil onto? A bit big, but for a test size does not matter?

And I got this even bigger core: http://at.farnell.com/ferroxcube/etd59-31-22-3c90/ferrite-core-half-etd59-3c90/dp/3056430?Ntt=3056430

@magpwr:

I was not successful with the radio wave receivers (as a power source). But I might have done something wrong.

I tried the copper and aluminium tube very close together in the earth, no success. It works very well when the tubes are wrapped in paper soaked in salt water, but I do not want to throw a lot of salt into my garden. But I will try fertilizer around the tubes in spring.

I like my "magpwr circuit in Epoxy" (see the photo in my last post) very much (besides its odd shape). I used it submerge in water, no problem. I will buy some clear casting resin and make a few more for outdoor use.

Greetings, Conrad

Offline gyulasun

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Hi Conrad,

Yes, the smaller sized core ETD49/25/16 is already okay, no need for the higher sized one. And do make some taps on the secondary if you agree.  Your question on the core size: on a bigger core the coils will have higher inductance than on a smaller one (cross section area is higher), this means  the oscillator would operate at a lower frequency with the bigger core.  Your E cores are surely good from some Hz to at least 100 kHz or maybe higher (3C90 material) so you have a very wide range available, by tuning the secondary with some hundred pF or maybe 1nF capacitor in parallel with it.  On your smaller core the 500 turns will give L=N2*AL=500*500*4.2uH=1050mH   i.e.  roughly 1 Henry inductance, this will resonate at about 22 kHz with a single 2SK170 JFET's gate-source input capacitance (nearly 50pF at 0.3V drain-source voltage from data sheet) if you do not use any other tuning capacitor. In case of 4 such FETs in parallel the frequency may go down to 11kHz or so.   (Of course these frequencies are rough estimates.)

Gyula

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Offline gyulasun

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Hi magpwr,

I also disagree with patenting in general, however, design engineers with big ego tend to do so and boost with their patents, you know it  sound good for them...  LOL

Regarding the radio wave charging battery idea: problem is I think that even if you are lucky to collect a few Volts in a capacitor of some thousand microfarad (not in a supercap) it does need a certain time to collect it, and if you wish to charge ultra or super caps by radio waves, it may take days to have them filled up to a certain level unless you live near to a higher power transmitter. Crystal radio receivers have in general a high output impedance and a charging capacitor is definitely a low impedance device, albeit it demands an exponentially decreasing current from an initial high value when fully or nearly discharged. However there exists a so called step charge process when you insure the voltage difference between the charger output and the capacitor is always small and gradually increased in small steps so that no huge inrush current. This step charge method is also a long process though and the control circuit also needs some power to work from.
Regarding the Germanium diode rectifiers, you may replace them with syncronous MOSFET switches IF you already have an RF voltage of near 1 to 1.5V across a resonant LC tank circuit fed from an antenna. I mean syncronous rectifier as shown with the ALD MOSFEts in the Cutler.pdf in TinselKoala's link BUT use logic level MOSFEts instead of the ALD types, the logic level types can already open and conduct at 1V or 1.5V positive peak voltage on their gate with respect to their source.

It is unfortunate that in your country copper tubes are a problem to buy. On ebay here are some copper tubes with an outside diameter of

1/8 inch: http://www.ebay.com/sch/i.html?_trksid=p5197.m570.l1311.R6&_nkw=1%2F8+copper+tube&_sacat=0&_from=R40

3/8 inch http://www.ebay.com/sch/i.html?_trksid=p5197.m570.l1313&_nkw=copper+tube+3%2F8&_sacat=0&_from=R40
             http://www.ebay.com/itm/Copper-Coupling-For-3-8-O-D-Tubing-One-Coupling-/400298753167?pt=LH_DefaultDomain_0&hash=item5d33aa3c8f

1/2 inch http://www.ebay.com/sch/i.html?_trksid=p5197.m570.l1311.R9&_nkw=1%2F2+copper+tube&_sacat=0&_from=R40

Regards, Gyula

...
hi gyulasun,

Thanks for providing some interesting links.It does help us to promote creativity in each of us.I never knew people actually patent ultra low voltage voltage booster.
Good thing mine is unique and i will never patent my design especially for simple "electronics".It would be a waste of effort or time maybe money to patent.
---------
I would be planning to work on this project to compliment my 25mV joule thief.It's using radio wave to charge battery.I will be using it with ultra-caps.
http://www.youtube.com/watch?v=tjxldE8JsDw

I was active in this forum where there was discussion on the "RF diode charger" and etc.
http://laserhacker.com/forum/index.php?topic=104.0

I noticed it's very difficult to find antique items in my country like 1N34A that i have to order online from ebay.
I had problems even finding small copper tubes normally used in Air-con smaller version for copper tube\toroid transformer to experiment on resonance as i mentioned earlier in this forum.

Offline magpwr

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Hi gyulasum,

Thanks for providing links to copper pipes/tubes on ebay,this will be the last resort as the shipment cost base on weight of copper would be  high.
I will still continue with search for copper tubes in my tiny island-Singapore -50km(~35miles) wide.
There is potentially some businesses that sell copper tubes further away from my place.

It's frustating after buying toroids online base on specs as shown in this original video -double amazing joule thief 150leds on 1 AA battery,but simple copper tubes can't be obtained easily.
https://www.youtube.com/watch?v=blVqaiYv_WU

I had already purchased  zero threshold ALD MOSFEts(QUAD) for culter radio noticed in document which author which mentioned produces 0.125volts at output.
Even it fails to provide sufficient power to 25mv joule thief maybe on "interval basis" from charged capacitor,it would be used as radio as plan B.

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Offline acmefixer

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I agree: much easier to wind.  Much more expensive, too, if you can get one the right size.  I've found a few in power supplies, but they usually require a lot of work to get them ready for winding.  If you're lucky you might find one that has the feedback winding already on the core.  Maybe with 200 or more turns on it.  Then it's easy to wind another few turns on the core for the primary.  I think if I want to spend the money on a core, I should just buy one that's already wound and ready for service.

Regarding taps...  I made it a lot easier to wind the toroid by just winding 50 turns of a manageable length of wire on at a time, then bringing it out and connecting it to another manageable length of wire, and on and on until I had 200 turns.  That's how it ended up in this picture (click on it multiple times).

Hi Conrad,

Thanks and may I suggest to make taps on the secondary coil at  1:50 and 1:75  turns ratio to make matching more flexible. Also, you could consider using ferrite pot cores or normal ferrite E cores instead of the toroid core shape, these latter cores are much easier to wind.

rgds, Gyula

Offline conradelektro

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@acmefixer: I looked at your blog http://rustybolt.info/wordpress/?p=5912 . According to my tests the 4:100 ratio on a toroid seems to be the best for the 2SK170 transistor (or for 4 of them in parallel). I even got the impression that 8:100 was slightly better (brighter LED at 50 mV, and for sure at 100 mV).

The coils are not the problem for even lower Voltages, it is the transistor. And one would have to go for a two stage circuit, if the power is there, which needs to be 10 mA in order to get 100 µW with 10 mV. About 100 µW is necessary to make a LED glow, starting with 1 mW one can claim that the LED shines (and one has to provide at least 2.2 Volt).

For me that concludes my work on this circuit for the moment. In Spring I will test several earth batteries with magpwr's circuit cast in resin in order to make the circuit weather and water proof. I want some glowing LEDs in my garden.

The earth batteries I have in mind (two different metals like copper and aluminium or galvanised steel) give at least 200 mV, the problem is Amperage. There are a few threads about earth batteries and I have to go through them to recall the ideas put forward. I do not want to use magnesium (too expensive and it corrodes pretty fast).

In case a reader knows a fairly good earth battery by heart, I would appreciate some hints. Magpwr's circuit opens up new possibilities because 50 mV would be enough (in case 2 mA can be drawn).

At the moment I have two 0.5 meter tubes (10 mm diameter) in the garden, straight down next to each other (copper and aluminium). They show 320 mV and 20 µA short circuit current. This is way too little power for a LED. I will try a copper pipe and a galvanised steel pipe (which I have yet to buy).

I will also try a good earth connection (2 meter long copper pipe straight down) and an antenna wire thrown over my wooden garden shed (or even wound around the shed at roof hight). In the Joule Thief thread there was some discussion about "ambient energy receivers", see http://www.overunity.com/6123/jule-thief/15975/#.UQqrGmckQfw, which I will test. Magpwr's circuit might do the trick to light one LED with this power source.

Greetings, Conrad

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Offline gyulasun

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Hi Folks,

Some relatively cheap sources of ferrite pot cores or pre-wound coils:

http://www.surplussales.com/inductors/FerPotC/FerPotC-1.html 

http://www.electronicsurplus.com/LeftNav/Inductors/Ferrite_ToroidCores.cat 

Of course, ebay can also be a good source but you have to "hunt" for cheaper sellers.

Gyula

Offline conradelektro

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My earth battery Joule Thief is now working:

It needed the ALD110900 (instead of the 2SK170) to make the circuit run on a very simple earth battery. The battery consists of a copper tube next to an aluminium tube driven into the ground (both tubes only 0.5 meters long, diameter 10 mm, about 5 cm distance in the ground). I also put a 1 meter copper pipe and an 0.7 meter galvanised post into the ground, but that was an overkill.

The LED is of course not very bright, but one can see it clearly from at least 10 meters away (in the dark).

See the attached drawing and photos. Note, it does not work with the 2SK170 because it draws too much power, which can not be sustained by the simple earth battery. Even the long tubes are not sufficient.

I will now put this circuit into a casting resin to make it weather proof.

Greetings, Conrad

Offline conradelektro

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Deleted, mistake!

Offline magpwr

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Hi conradelektro,

Interesting oscillator circuit using ALD mosfet.

I was curious about the efficiency for the ALD based circuit.
Using :200mV x 250uA (Found in uploaded image)

I used VoltsxI(Amps) =0.2v x 0.00025A =0.00005 watts or 50mW (Current consumption to light led)

I then try to apply for my 2SK170 circuit VxI =60mV x4.2mA=0.00000252 watts or 2.52mW(Current consumption to light led)

But i noticed my circuit current draw is higher for lower voltage requirement although efficiency wise the 2SK170 base circuit looks better.
Maybe it make sense why ALD mosfet is preferred choice for  radio.

 

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