I 've got my 2sk170 , Thx magpwr for this wonderful circuit , thanks to u guys  too for helping

hi omdano,

Don't forget to post a photo of your completed circuit  with led lit once you get it running.

Cheers.

I am going to make you more than that , Just wait for april .

Edit :

One question
if i had 2 peltiers , each producing 100mV , i want to put them in series to produce 200mV
won't the second peltier just suck up the voltage and turn it into heat ?

My opinion:

It is fine to put Peltier elements in series (in order to have higher Voltage). But the current can not be more than the current from the weaker element. The elements will give the same current if they have the same temperature and the same temperature gradient (between the hot and cold side) and if they have the same size and make.

If one puts Peltier elements in parallel (in order to have more current) they should have roughly the same temperature and the same temperature gradient  (between the hot and cold side), also same size and same make.

Simply said: if you use more than one Peltier element (either parallel or in series) make sure they have the same conditions on their hot and on their cold side (of course the hot side is hotter than the cold side). This might not be easy to achieve. A smaller Peltier element will heat up faster than a bigger element. Different brands will have a different heat conduction.

If you want to keep it simple, use just one element. Peltier elements are available in different sizes (it soon becomes expensive, 50 x 50 millimetre elements are already expensive). I found that 30 x 30 mm or smaller Peltier elements are pretty useless at low temperature differences.

Peltier elements become usefull if a temperature difference of 200° (centigrades) is available, which implies very good cooling on the cold side. Getting the heat on the hot side is fairly easy (open flame), but the cooling on the cold side is difficult (in practical terms). Usually some water cooling is arranged.

Peltier elements are ususally used as sensors (providing very little power) and not as a generator (providing useful power).

Peltier elements are in general not a very useful power generator technology on earth. But in space the sing, because the cold side is simply exposed to space (near absolut zero) and on the hot side is usually a nuclear reaction providing heat for years. You do not want a nuclear reaction near you and you do not have absolut zero near you.

Greetings, Conrad

So... did anybody try to Oscilloscope the output of this circuit ? (with any voltage input - please mention)

Well, I don't have a 2sk170 but I've certainly posted plenty of JT scope traces. And LTseung has a thread that is mostly discussion of scopetraces from his JTs.

Yeah because .. i would love write an equation for the JT circuits inputs and outputs
to make things simpler .

is there an easier way for winding the 100 windings ? XD

Well ..  so..  How did u measure the voltage in the video ?
People usually use Oscilloscope but you just simply used a multimeter
Where did u connect the multimeter ?
(the output circuit voltage)

Well ..  so..  How did u measure the voltage in the video ?
People usually use Oscilloscope but you just simply used a multimeter
Where did u connect the multimeter ?
(the output circuit voltage)

hi omdano,

There is no need for Oscilloscope since we are working with DC.

You will need to the "fix" hot or side for the peltier(which effect which wire from peltier produce + or -) since you are going to connect to 100uf or 1000uf capacitor at the input of joule thief(+ -).

The peltier (+ -) output is connected to multimeter and joule thief output is connected to multimeter in video.This is just for demonstration purpose.

This joule thief circuit can be completed in few hours since 100 winding for toroid will take some time."Need alot of patience"

That's all the advise i can give."Good Luck"