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Author Topic: Joule theif : try out !  (Read 34589 times)

omdano

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Joule theif : try out !
« on: January 06, 2014, 01:35:30 PM »
Hello i just bought a couple of peltiers and i want to light a led with 20/30mV with a joule theif

i am new to this forum :D so.. can anybody be a dear and give me a schematic and suggest me some transistors i can find in market ?
(this turned into my new hobby :p )

Thanks guys

TinselKoala

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Re: Joule theif : try out !
« Reply #1 on: January 07, 2014, 08:53:43 PM »
Oh yes. You should look at the various JT threads here. It's kind of surprising that none are active at the moment. There are many many circuit variations.

Just about any NPN transistor will work, but good ones for low-power are
BC337
2n2222a
mpsa18
2sk170

You may find this video amusing:

http://www.youtube.com/watch?v=tuFWC-yyIyU

xee2

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Re: Joule theif : try out !
« Reply #2 on: January 08, 2014, 01:56:51 AM »
Hello i just bought a couple of peltiers and i want to light a led with 20/30mV with a joule theif

i am new to this forum :D so.. can anybody be a dear and give me a schematic and suggest me some transistors i can find in market ?
(this turned into my new hobby :p )

Thanks guys


A Joule thief generally requires at least 0.7 volts to operate. This can be reduced to about 0.2 volts using germanium transistors as in http://www.youtube.com/watch?v=XQ7dua2mBzo. However, I do not think 30 mv will work.




TinselKoala

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Re: Joule theif : try out !
« Reply #3 on: January 08, 2014, 03:47:26 AM »
Ah, you are right. For some reason I read the OP as "20 or 30 milliAmps" instead of mV.

The lowest I personally have seen one work is about 300 mV on the supply.


omdano

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Re: Joule theif : try out !
« Reply #5 on: January 08, 2014, 10:59:40 AM »
So.. i measured the voltage straight out of my peltier .. it is about 0.1 volts .. It seems that i have underestimated my peltier .. so... is there any way i can boost it ?
(i can use 2 peltiers :p)
So.. a schematic will be Wonderful

xee2

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Re: Joule theif : try out !
« Reply #6 on: January 08, 2014, 07:56:57 PM »
So.. i measured the voltage straight out of my peltier .. it is about 0.1 volts .. It seems that i have underestimated my peltier .. so... is there any way i can boost it ?
(i can use 2 peltiers :p)
So.. a schematic will be Wonderful


Yes, you can put peltier units in series to get higher voltage. I have not tried the 25 mv circuit in video, but that may be your best option.


infringer

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Re: Joule theif : try out !
« Reply #7 on: January 09, 2014, 02:12:43 AM »
Have you tried fixing them to your window to see what you can get out of them top end that is if you live in a cold area...

That should be the biggest temp difference in your home.

Anyhow good luck with your project I would suggest getting like 10 of these and trying to run a light that way you should have a safe voltage then...

But I will tell you that they do make indoor solar cells that can absorb solar from your indoor lighting to charge a battery this is another option depending on which direction you are willing to go...

omdano

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Re: Joule theif : try out !
« Reply #8 on: January 10, 2014, 11:57:50 AM »
I have searched in the 25mv thread for a schematic but didnt find one , if anybody gets the luck help me and post it here :p

omdano

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Re: Joule theif : try out !
« Reply #9 on: January 19, 2014, 09:22:29 PM »
So... As in this circuit :http://www.youtube.com/watch?v=XQ7dua2mBzo

i can replace them with any germanium transistor or is there any specific types ?

Can i get the transistors that work with such a circuit so i can buy them ?
thanks very very very much



xee2

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Re: Joule theif : try out !
« Reply #10 on: January 20, 2014, 12:00:50 AM »
i can replace them with any germanium transistor or is there any specific types ?


Any NPN germanium transistor should work, but they are not easy to find. Note that germanium transistors do not work as good as silicon transistors so the circuit will not perform as well as a regular Joule thief.


You can use a PNP germanium if you reverse the battery.


Jfet schematic below (note, I have not built this so I do not know if it works). Circuit by sanjev21.


What you are trying to do is not easy. I suggest starting with something like this http://www.youtube.com/watch?v=D7CFkRLrtss for your first Joule thief.


omdano

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Re: Joule theif : try out !
« Reply #11 on: January 20, 2014, 12:50:13 PM »
Yea but i am looking for something to work with a 0.2 volt input

forest

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Re: Joule theif : try out !
« Reply #12 on: January 20, 2014, 01:38:03 PM »
Try some energy harvest electronics to step up voltage

omdano

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Re: Joule theif : try out !
« Reply #13 on: January 20, 2014, 05:40:51 PM »
About this circuit Xee , I would love to know .. If i use different Transistor (yes it is germanium ) , What will change in the circuit ?
And how can i calculate the differences , Thanks very much.

From your schematic : http://www.overunity.com/8629/peltier-candle-powered-jt/#.Ut1WXsqmq60
in your post

omdano

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Re: Joule theif : try out !
« Reply #14 on: January 21, 2014, 01:17:31 PM »
Btw : Can i in anyways make a joule theif with 200mv Input and a 2SC1815 GR331 transistor ? http://pdf1.alldatasheet.com/datasheet-pdf/view/428752/MCC/2SC1815-GR.html
Cause i have been told about this one being good for a try