25mV Joule Thief powered by peltier merely using our body heat -Free energy 24/7

[gyulasun]

Hi magpwr,

I have done some search on very low collector-emitter saturation voltage transistors and found the following type:
ZXT13N15DE6  Vcesat=5mV at Ic=100mA   and  45mV at Ic=1A  data sheet http://www.diodes.com/datasheets/ZXT13N15DE6.pdf  and available at Mouser ( http://uk.mouser.com/Search/Refine.aspx?Keyword=zxt13n15 )

Regarding the JFET types I wonder if you tested already the so-called switching or chopper type JFETs like J105, J106, J107, J108 or J109 ?  They have 3 Ohm to 18 Ohm drain source ON resistance, respectively, at zero gate source voltage.  What do you think? Their transconductance is not specified due to the switching purpose of operation but it is surely inherently pretty high.  Here are prices and data sheets: http://uk.mouser.com/Semiconductors/Discrete-Semiconductors/JFET/_/N-96ngcZscv7?Keyword=j10&FS=True  Notice that in the Vertical Column Drain Current (Idss at Vgs=0) the currents are wrong (like 0.005mA) just study the data sheets.

Regarding your idea, it sounds very interesting and as a shaking solution you may wish to consider the vibro motor of cell phones: they are tiny electric motors with an small weight fixed to the rotor shaft in eccentric position. Unfortunataly they have very high RPM (several thousand) but maybe giving them much less supply voltage could help on this. Here is what I mean:
http://tinyrc.com/qfm/racing/dls/microspec.htm   but there are many types due to the variety of mobile or cell phones or pagers.

Thanks for all the great work.

rgds, Gyula

EDIT  magpwr: I have just read through your earlier posts and noticed you already mentioned the J series of JFETS are not good (if you really meant J105 to J109 as I wrote above) and you also hinted at using vibrating motors to replace Peltier cell.  So sorry for "reinventing the wheel" LOL  that was unintentional.

[magpwr]

Hi gyulasun,

It seems the 4th generation transistor link you shown me (VCEO=15V; RSAT = 29mOhms ; IC= 5A) could compete with mosfet.

But those component are smd(Surface mount version).
For testing and creating prototype it's better to use transistor that could be added and removed easy from test board.

I have already tested all jfet series JXXX and all of those didn't work.I have mentioned it somewhere in my youtube channel title 25mv Joule thief.

I need to have time to work on my plans especially gas heatsink with peltier underneath, heatink under peltier as well.
If i move it by hand it should generate electricity.But i realised water could be created from condensation at the lower part of gas heatsink.
Unless peltier output is connected to joule thief to generate higher seeback which might prevent water formation from happening.Not tested yet.

[gyulasun]

Hi gyulasun,

It seems the 4th generation transistor link you shown me (VCEO=15V; RSAT = 29mOhms ; IC= 5A) could compete with mosfet.

But those component are smd(Surface mount version).
For testing and creating prototype it's better to use transistor that could be added and removed easy from test board.

...

Hi magpwr,

Thanks and I agree, it is not convenient to fiddle with SMD components.  For test purposes I often used SMD component prepared with color wires of 3-4 cm long soldered to the SMD so you actually deal with or plug into the testboard the end of short wires.

In the meantime I found similar very low saturation type, seems they are manufactured in SMD nowadays.
Vceo=20V  Rsat=18mOhm   Ic=7A       http://www.mouser.com/ds/2/115/ZXTN19020CFF-77912.pdf   

Good luck with your plans on gas heatsink with Peltier underneath.

rgds,  Gyula

[acmefixer]

Have you tried the J105 or TN0702 FETs for a low voltage JT?  The trick is to get it to start by itself.  I also put a 1.5V button cell in series with the gate to reduce the voltage needed to get it to conduct.  The gate draws zero current so the cell lasts almost forever.

You can get some good ideas from the schematic and information for a low voltage converter (.PDF) found here.

Hi conradelektro,

Nice work man.This is how 1st started with <100mV Joule Thief using transistor 2SD1450 (0.13v..0.3v VCE(voltage drop between emitter and collector at 400mA.By referring to datasheet and looking at vce
for expected circuit current draw.

If you refer to my youtube channel  "sanjev21" "45mV Joule Thief" was my 1st low power joule thief  using  "2SD1450" Japanese transistor.But it was not self starting and i had to manually short emitter and collector of transistor to kick start oscillation.

My other experiment which i have not posted in youtube using the best NPN transistor i could find in digikey "ZTX1048A" which have the lowest Voltage drop across emitter&collector at mere(27mV...45mV) at 500mA.Little smaller than TO92 and could handle 4Amps or 20Amps pulse no "heat sink".
Using this ultra low drop transistor i could achieve oscillation as low as "30mV" but as usual i have to kickstart oscillation at higher voltage eg:60mV by temporary shorting emitter&collector.

I have also combine ZTX1048A transistor(To boost output current) and (2SK170 or 2SK364 or 3SK366 .But take note 2SK170 do have better lower starting voltage by 1..3mV)  Junction-FET(To self start osc at low voltage).Connecting 22ohms from coil to transistor and 1.8k coil to JFET Gate while connecting (JFET Source to transistor emitter,J-FET Drain to transistor Collector).Design for <100mV.

For this above transistor and JFET combined circuit i was able to charge 1000uf cap in matter of <5sec to reach around 2volts.

But the current drain for above transistor with JFET circuit  is  around 100mA .
I was using 50FARAD 2.5v Ultra capacitor(charged with 1AA battery for few seconds to reach 100mV) as power source.Since it's known ultra cap got very low internal resistance.

The above circuit will work very nice on 1.5V battery but need to tweak 22ohms resistor to higher value to maintain current draw at decent level eg:100mA.
Then again i realised it's pointless using JFET for 1.5v battery since we could use transistor which is more efficient at higher current.

Peltier only produce <5mA if I connected to multimeter if i use my hand as heat source(36.5c) against room temperature in my case(30c for a hot country) 6.5C difference.
The peltier i'm using do have internal resistance of around 3ohms(Out of the box /Not in use).
In theory i'd believe if we use lower internal resistance for peltier <2ohms we may get better current output but then again.I 'm not sure if multi meter could properly detect "current" at such low voltage produce from peltier 70mV..90mV.

Solar cell do work to power my JFET base joule thief in room lighting or led light.I'm not sure if using other power source like from crystal radio could work.

If we match "source and circuit impedance" then we could  further optimize on efficiency.


Lastly the circuit do work on 1 x 2SK170 as well with lower Circuit current draw at 1mA using peltier at around 60mV. I used 4 JFET  since i noticed there is improvement with output voltage especially with Led as load current draw increases to 4.2mA(Mentioned in youtube description).

Lastly if anyone wish to go for extreme low starting voltage at 22mV instead of 25mV got to try 2n3972 JFET (But very low current handling in itself output capacitor cannot be more than 100nf) and combine with 2SK170 x 3 or 4.

If anyone is a expert with SMD base tiny circuits there is UK base company which manufacture 2SK170 as LSK170  (TO92 package and SMD tiny version).
http://www.micross.com/packaged-parts-plastic-discretes.aspx

[conradelektro]

Have you tried the J105 or TN0702 FETs for a low voltage JT?  The trick is to get it to start by itself.  I also put a 1.5V button cell in series with the gate to reduce the voltage needed to get it to conduct.  The gate draws zero current so the cell lasts almost forever.

You can get some good ideas from the schematic and information for a low voltage converter (.PDF) found here.

@acmefixer: How good and interesting magpwr's circuit with the 2SK170 transistor is (if one has a very low Voltage power supply), can be seen from the fact that neither the circuits discussed in your blog nor the circuit from the PDF document can reach down to 25 mV. The voltage converter in the PDF-document needs at least 0.3 Volt and the circuits in your blog seem to use ordinary 1.5 Volt batteries.

I carefully verified magpwr's claim. With 4 transistors 2SK170 the circuit consumes about 2.2 mA at 50 mV (110 µW); a white LED glows nicely, of course not super bright. And one can make a LED glow by touching the hot side of a Peltier Element with the hand (the cold side at room temperature).

In case one uses only one 2SK170, the power consumption at 50 mV is about 500 µA (25 µW, the LED glows less bright)

Now, show me a circuit and a transistor which can do better (less than 50 mV supply Voltage and less than 500 µA supply current to make a white LED glow, self starting). This might not be very useful, but it is an interesting experiment.

Greetings, Conrad