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Author Topic: 25mV Joule Thief powered by peltier merely using our body heat -Free energy 24/7  (Read 302137 times)

magpwr

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Hi Scratchrobot,

The input capacitor is 100uf and output i'm using 1uf(105 written on cap) for quick increase in voltage you could use higher cap like 100uf at output stage as well and notice how fast the voltage will increase.
Or if your are just powering led 100nf caps will do as well at the output stage.

The toroid and circuit could be shrunk alot more ,it's up to individual builder. Prototype is always bigger/ugly initially since we don't know if it would work the way we want it.


I am indeed  bad at hand writing  rarely get the chance to write these days unless i am filling in some official document.

scratchrobot

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Hi Scratchrobot,

The input capacitor is 100uf and output i'm using 1uf(105 written on cap) for quick increase in voltage you could use higher cap like 100uf at output stage as well and notice how fast the voltage will increase.
Or if your are just powering led 100nf caps will do as well at the output stage.

The toroid and circuit could be shrunk alot more ,it's up to individual builder. Prototype is always bigger/ugly initially since we don't know if it would work the way we want it.

I am indeed  bad at hand writing  rarely get the chance to write these days unless i am filling in some official document.

I'm waiting for my fets to arrive and when i have them i will build your circuit and report back here.
Thanks again for sharing your circuit.

scratchrobot

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The Fets arrived and i tried replicating your circuit but without succes. I will try making another coil.

TinselKoala

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Be sure to try all combinations of coil connections before you change other stuff. Say you have coil A with connections 1 and 2, and Coil B ditto.
So you have 4 possible ways to hook up the coils; two should work and two won't, and of the two that do, one might be a little better.


conradelektro

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I like this circuit and the use of peltier elements.

Unfortunately I have to get this special transistors before I can start experimenting. I have a good collection of peltier elements. My idea is to stick the peltier element to a cold window glass and a longish aluminium "heater" warmed up by the air in the warm room.

The use of 4 transistors is still a riddle for me: my guess is that one transistor would suffice once the one amongst the four is found which switches most easily with this low Voltage and low current at the base. But I could be wrong. The argument, that 4 transistors give more power than 1 in case they do not switch on nicely is not very good, because 4 times very low power would still not be enough. The trick is to make the transistor switch on inspite of low Voltage and low current at the base. Once that is achieved, it does not matter whether it is 1 or 4 transistors. There could be a strange interaction between the bases of the four transistors, but this seems to be esotheric. What ever, in case 4 work, why not.

Greetings, Conrad

conradelektro

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Theory concerning 4 transistors in parallel versus just 1 transistor:
 
The base of a transistor is also a small parasitic capacitor. Having 4 transistors (4 bases) in parallel will multiply this parasitic capacitor by 4. A charge will accumulate in this capacitor and it will flow into the one transitor that triggers by chance as the first one (the other 3 will not trigger and at each cycle an other transistor of the four transistors could trigger but my guess is that always the same triggers due to very fine diferences in the production process).
 
The charge is sufficient to trigger one transistor if it is accumulated in 4 bases but is not sufficient if it can only accumulate in one base.
 
Putting a 1nF capacitor in parallel to the 1-8K base resistor should do the same. May be a smaller capacitor of e.g. 500 pF will be better.
 
Greetings, Conrad

gyulasun

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Hi Conrad,

If I may chime in here,  no need for thinking that the 4 transistors in parallel may behave esotheric. The 4 in parallel has 2 useful benefits: the resultant drain-source channel ON resistance becomes 1/4 of that of a single transistor so that the power loss (I*I*R) due to the smaller channel resistance is also 1/4 only.
The second benefit is that the resultant forward transconductance (or forward transfer admittance) (dVgs/dId) becomes 4 times as high than that of a single transistor. 
So the reason for paralleling them is to improve manufacturing "deficiences" on certain important parameters for an oscillator. Of course unwanted parameters also occur when paralleling: input and (output) capacitances get also 4 times as much, this would not be needed at all...  should a device in a circuit need higher input capacitance, you could always add some to see any benefit.

Here is a data sheet for the 2sk170:  http://www.audiodesignguide.com/DACend2/2sk170.pdf  and you can order cheaply from futurlec.com for instance.

Greetings,
Gyula

conradelektro

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Hi Conrad,

Here is a data sheet for the 2sk170:  http://www.audiodesignguide.com/DACend2/2sk170.pdf  and you can order cheaply from futurlec.com for instance.

Greetings,
Gyula

@Gyula: thank you for your input. Looking at the data sheet I see a "reverse transfer capacitance CRSS" of 6 pF. So, a 22 pF capacitor parallel to the 1-8 K base resistor should do the same. But there might be the other considerations you mentioned. It has to be tested, theory is just words.
 
Greetings, Conrad

scratchrobot

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Be sure to try all combinations of coil connections before you change other stuff. Say you have coil A with connections 1 and 2, and Coil B ditto.
So you have 4 possible ways to hook up the coils; two should work and two won't, and of the two that do, one might be a little better.

Thanks but i tried every possible way but nothing was working for me. I will try again tomorrow and also hook up a scope to see if i get oscilations. Not easy testing this with one finger on the peltier, Magpwr where are you  ;-)

TinselKoala

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Thanks but i tried every possible way but nothing was working for me. I will try again tomorrow and also hook up a scope to see if i get oscilations. Not easy testing this with one finger on the peltier, Magpwr where are you  ;-)
Test with a stable voltage source like a regulated power supply or a battery. When the circuit works, then sub in the Peltier.

magpwr

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Hi scratchrobot,

I would like to check with you only 3 things to find out why circuit isn't working for you.

1)Are you using the most ideal N Channel Juntion FET-2SK170 (1 or 4 should work as well).I have not mentioned in video.Please don't bother trying with other N-Channel JFets(>30 varieties ) the result isn't good (not as low startup/osc)or worst don't even osc at 100mV or can't simply handle low impedance at primary(4 turns).

2)Is your primary (4 TURNS) and Secondary is around 80...100(Even 70 turns do work on smaller toroid,but open circuit voltage would be lower,with 10mm led voltage remains same around 2.3v ...2.4v)
May need to swap secondary turns ( One of the 2 output to positive)

3)Have you verifed the output voltage from peltier(+ - output with hand on itand heatsink) before even connecting to circuit.Please google datasheet of N-Channel J-FET to identify pinout(Drain ,Gate ,Source = C ,B ,E)Lastly peltier in itself(not with hand or on heatsink) ,out of the box should have low impedance reading <5Ohms.
   My peltier is 3Ohms .My toroid primary is <1Ohms with 4 turns.I think in theory peltier which got lower impedance may produce good result.


Lastly you could check toroid connection merely using common NPN transistor with 1.5V battery if there is no output just swap secondary (one of the 2 wires to + and primary one of 2 wire to +)
 
Have a Happy New Year.

magpwr

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Hi scratchrobot,

I would like to check with you only 3 things to find out why circuit isn't working for you.

1)Are you using the most ideal N Channel Juntion FET-2SK170 (1 or 4 should work as well).I have not mentioned in video.Please don't bother trying with other N-Channel JFets(>30 varieties ) the result isn't good (not as low startup/osc)or worst don't even osc at 100mV or can't simply handle low impedance at primary(4 turns).

2)Is your primary (4 TURNS) and Secondary is around 80...100(Even 70 turns do work on smaller toroid,but open circuit voltage would be lower,with 10mm led voltage remains same around 2.3v ...2.4v)
May need to swap secondary turns ( One of the 2 output to positive)

3)Have you verifed the output voltage from peltier(+ - output with hand on itand heatsink) before even connecting to circuit.Please google datasheet of N-Channel J-FET to identify pinout(Drain ,Gate ,Source = C ,B ,E)Lastly peltier in itself(not with hand or on heatsink) ,out of the box should have low impedance reading <5Ohms.
   My peltier is 3Ohms .My toroid primary is <1Ohms with 4 turns.I think in theory peltier which got lower impedance may produce good result.


Lastly you could check toroid connection merely using common NPN transistor with 1.5V battery if there is no output just swap secondary (one of the 2 wires to + or swap primary one of 2 wire to +).
If works then use JFET with lower voltage or ultra cap eg:50F 2.5v charged using 1AA for 1..3 seconds to get around 100mV,if you are not using peltier to test.Since Ultra caps eg:20F...50F got very low impedance as well.
 
Have a Happy New Year.

scratchrobot

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Hi scratchrobot,

I would like to check with you only 3 things to find out why circuit isn't working for you.

1)Are you using the most ideal N Channel Juntion  (1 or 4 should work as well).I have not mentioned in video.Please don't bother trying with other N-Channel JFets(>30 varieties ) the result isn't good (not as low startup/osc)or worst don't even osc at 100mV or can't simply handle low impedance at primary(4 turns).

2)Is your primary (4 TURNS) and Secondary is around 80...100(Even 70 turns do work on smaller toroid,but open circuit voltage would be lower,with 10mm led voltage remains same around 2.3v ...2.4v)
May need to swap secondary turns ( One of the 2 output to positive)

3)Have you verifed the output voltage from peltier(+ - output with hand on itand heatsink) before even connecting to circuit.Please google datasheet of N-Channel J-FET to identify pinout(Drain ,Gate ,Source = C ,B ,E)Lastly peltier in itself(not with hand or on heatsink) ,out of the box should have low impedance reading <5Ohms.
   My peltier is 3Ohms .My toroid primary is <1Ohms with 4 turns.I think in theory peltier which got lower impedance may produce good result.


Lastly you could check toroid connection merely using common NPN transistor with 1.5V battery if there is no output just swap secondary (one of the 2 wires to + and primary one of 2 wire to +)
 
Have a Happy New Year.

Hi Magpwr,

My mosfet's are J175 so maybe they are not the one's you used and they are the reason the circuit isn't working for me.
My peltier without heatsink reads 5 ohms without a heatsink and with heatsink and one finger gives 25mv easely.
I will try with normal transistor to see if i can get it to work.

Thanks and happy new year to you too.

magpwr

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Hi Scratchrobot,

I'm sorry you had to find out the hard way.I did mentioned somehwhere in youtube description or comment to another interested person whom wish to construct the ultra low voltage circuit.
Never to try any Jxxx series all those don't work.I have done stimulation testing using trial software to find out the best component(It's on you to find out.I won't reveal it).
Please don't bother trying other Junction FETs you won't get ultra low self startup voltage.I have wasted 3 days to accidently discover a self starting joule thief at below <30mV while trying to optimise joule Thief.

I bought 2SK170 from  http://www.futurlec.com  (After searching in internet high and low) for $0.20ea (Bought 10 pieces for $2 USD) Since i'm living in Asia shipment is only around $5.50USD for me.Got it within  2 weeks.

Recent discovery my circuit could be powered by solar cell in room merely shine a led torchlight to part of the 1.7v solar cell(400mA) to light a led again from my ultra low joule thief(NOT OVERUNITY).

conradelektro

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I am still waiting for delivery of some 2SK170 transistors. But I tested magpwr's circuit with transistors I had (see attached circuit diagram and photo, photo shows test with a BC547B).

2N3904 : self starts to oscillate at 0.52 Volt  and can then be turned down to 0.17 Volt

2N4401 : self starts to oscillate at 0.5 Volt  and can then be turned down to 0.1 Volt

BC574B : self starts to oscillate at 0.49 Volt  and can then be turned down to 0.14 Volt

I also tried with 10 turns for the collector coil, but 4 turns worked better (same self start voltages, but with 4 turns the LED showed some light with less supply Voltage). 4 and 100 turns seems to be a good ratio for the coils.

The 1 µF capacitor over the LED had no effect (also tried other values like 100 nF).

The resistor at the base influences power consumption very much. With 1 K the power consumption at 0.5 Volt was around 15 mA. With 10 K it was too low to be measured reliably, less than 1 mA.

I have redrawn magpwrs's circuit to give it a more conventional look. The LED is driven by the negative halve of the base coil spike. The positive halve of the spike triggers the transistor.

So, it really seems to be the transistor which is the determining component. On Monday I should get the 2SK170 transistors.

Greetings, Conrad