I added a power MOSFET, it drives the output via an extra turn on the transformer, At 15 mV the LED comes on. more light, the resistance of the thermocouple wire I use now really limits power (= LED current)
The sky is the limit I think.
New circuit diagram, update part in red:
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I have ordered 2 E type 600 °C thermocouples from ebay for more power experiments. This should also rock on a single solar cell? Those are ordered too.
I got mine off of ebay. I've soldered antennas in the field with this lighter. It will quickly light an Esbit or a camp fire. It has a platinum wire by the flame that does some magic to make the light more wind resistant.
Hardware stores in the US stock gas furnace "thermocouples", but really they are thermopiles. I don't know if they can be adapted for your use. I saw the thermopiles you ordered off of ebay and that is probably the best route since they have spade lugs on them.
On a sunny day (Tue, 02 Oct 2012 12:07:05 -0700) it happened miso wrote in :
transformer,
current)
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experiments.
Looks good, 1300 °C is nice too. But I get 4 lighters for an euro or so?
I did some research, the 'flame sensor rods' (like ebay 350299611985) are just simple thermocouples, and cheap, 6 or 7 $. Those are very suitable, but only give 25 mV open circuit see:
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The thermopiles are BIG (that is long) and start above 25 $.
So I ordered some type E (ebay nr 230851975230) No need to keep them IN the flame, at a max temperature of 600 °C they give 43 mV open circuit, beating all others. The current circuit already starts at 15 mV, one would think for 100% power transfer 21 mV across the thermocouple and 21 mV across my circuit. I can now light the LED by holding the type K home made (twisted wire) thermocouple a bit above the flame. It is not a project, although I suggested in sci.physics to ask a million from DOD to research 'soldiers equipment powered by body heat', LOL, 30 type K will do...
And actually, now we have some stabilized ! 2V across the LED, I can run a PIC, it is a negative voltage so it should be upside down, but there are many interesting things you can do with a PIC, although in this case I have not been able to think of one... :-) Its all just play, a proof of concept, and I think it was Martin Brown who a while ago asked about it here. Nice for a science fair. Well there you are Martin, if you are still around. I have some solar cells on order, and this was also just a muscle training g for a .5 V single cell converter. I have a hundred watt on the way (ebay nr 180958528777) 36 panels of .5 V 6 A each It is for that 6A where the power MOSFET comes in... If the nukes fall at least I will be able to power my short wave radio, and that is an other chapter altogether. Now lets talk about that Si4735 FM AM chip, any experience with that?
are just simple thermocouples, and cheap, 6 or 7 $.
give 43 mV open circuit, beating all others.
er transfer 21 mV across the thermocouple and 21 mV across my circuit.
ermocouple a bit above the flame.
from DOD to research 'soldiers equipment powered by body heat',
a PIC, it is a negative voltage so it should be upside down,
this case I have not been able to think of one...
o a while ago asked about it here.
g g for a .5 V single cell converter.
6 A each
nd that is an other chapter altogether.
I've been through these exercises some time ago, and concluded it's well worth putting two solar cells (or more) in series. You can make very low input voltage converters--and I did--but the i^2*r losses kill efficiency. There's no getting around it.
Low Vce(sat) BJTs excel in this application, at least when I looked. MOSFETs may have improved.
Of course, if 25mV is all you have, your approach is pretty cool. I mean hot. I mean...oh well.
Now try the reverse, the Joerg version: Lighting a lighter with an LED. Once. Pzzzzt SNAP!
On a sunny day (Wed, 03 Oct 2012 00:28:10 -0700) it happened miso wrote in :
As far as I know in RTG (radio thermal generators) the plutonium heats a whole lot of thermocouples in series, those are mounted in a circle, inside on hot plutonium, outside on huge heat sink fins.
Several hundred Watt for several decennia is achieved.
Voyager is still having enough power for science and transmission today.
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