Author Topic: Thermopiles  (Read 2403 times)

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Offline Melcin PowellTopic starter

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Thermopiles
« on: January 04, 2011, 01:46:16 PM »
This isn't really a robot but it is still electronics. Could i use transformers to up the voltage of a Thermopiles voltage? Say i wanted to light up 7 leds using heat

Offline waltr

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Re: Thermopiles
« Reply #1 on: January 04, 2011, 01:58:38 PM »
A transformer requires a changing current (AC) to create a magnetic field in the windings. This would not work with DC.

You could use a DC-DC boost power supply (switcher) to transform a voltage to a higher voltage.

Offline madsci1016

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Re: Thermopiles
« Reply #2 on: January 04, 2011, 02:03:59 PM »
Nothing will increase power from a thermopile. They don't produce much at all, not nearly enough for 7 LEDs unless it's a really big one.

Offline Fr0stAngel

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Re: Thermopiles
« Reply #3 on: January 04, 2011, 03:20:08 PM »
lets see....an average thermopile available today produces 1-2 milivolts od voltage and current in micro amps.
an average LED may run on 3-8 volts and draws 15-20 milliamps current...now you can do the rest of the math.. ;)

and like waltr said, transformers only operate on AC voltage. thermopiles produce DC. U can use a high gain op-amp to run LEDs using the thermopile output though.
« Last Edit: January 04, 2011, 03:23:15 PM by Fr0stAngel »
'crazy' is the new hype! =)

Offline Melcin PowellTopic starter

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Re: Thermopiles
« Reply #4 on: January 04, 2011, 09:48:26 PM »
Ok thanks guys i was looking for a switcher online but i couldn't find one that takes in less then a volt. And how does the op-amp work could it increase the volts and amperage of thermopiles?

Offline Soeren

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Re: Thermopiles
« Reply #5 on: January 06, 2011, 12:10:46 AM »
Hi,

And how does the op-amp work could it increase the volts and amperage of thermopiles?
Yes, as long as you remember that there's no such thing as a free lunch.

An op-amp, or a transistor, can amplify both the current and voltage of your sensor as long as the amplifying element are fed from a supply that can deliver what you want.

An amplifier is not a magic component that gives out more than it gets, but rather a controller where a small control voltage or -current is commanding it to open a "tap" on the "main line" more or less.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Melcin PowellTopic starter

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Re: Thermopiles
« Reply #6 on: January 09, 2011, 10:23:06 PM »
I was only able to find one website that sells thermocouples http://www.customthermoelectric.com the only problem i had with this site is how expensive the thermocouples are.  Anyone know any other sites i could visit.

Soeren I am kinda confused are you saying i would need a battery to get the op-amp to work because the thermocouples  won't supply enough "juice"
And Thanks

Offline Soeren

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Re: Thermopiles
« Reply #7 on: January 10, 2011, 11:47:01 AM »
Hi,

I was only able to find one website that sells thermocouples http://www.customthermoelectric.com the only problem i had with this site is how expensive the thermocouples are.  Anyone know any other sites i could visit.

Soeren I am kinda confused are you saying i would need a battery to get the op-amp to work because the thermocouples  won't supply enough "juice"
And Thanks
Oh, you are talking about Peltier elements. I was thinking of something like a pyroelectric detector.
So, forget what I said.

A Peltier is not really suitable for generating power, although it can, if you make a thermal difference from one side to the other of eg. 70°C or more (depending on the actual element). How do you plan to accomplish that?
I haven't looked too far into the difference of their regular Peltiers and their "generators", but a regular Peltier should do.

For cheaper Peltiers, go to sites selling overclocker items for PC's.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Melcin PowellTopic starter

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Re: Thermopiles
« Reply #8 on: January 10, 2011, 08:19:01 PM »
I've just been looking at the different possibilities of converting heat to electricity i was thinking of using it for a barbecue pit or something with a hot surface. so what i would do is place the hot side on the barbecue pit which would create enough difference in temperature to create enough current to light several LEDs. Still just trying to figure out how i could do it.


Thanks again for the feedback.

Offline Soeren

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Re: Thermopiles
« Reply #9 on: January 11, 2011, 05:11:29 AM »
Hi,

I've just been looking at the different possibilities of converting heat to electricity i was thinking of using it for a barbecue pit or something with a hot surface. so what i would do is place the hot side on the barbecue pit which would create enough difference in temperature to create enough current to light several LEDs. Still just trying to figure out how i could do it.
I doubt that you'd get much temp. difference that way (apart from a very short term diff. at initiating time), as the entire brick will heat up. You'd have to actively cool the other side to get a usable result.
You'd need a diff. of around 80° to get 1.8V at around 740mA with the smallest of their "power generation" devices, just enough for a red LED, but with no overhead for current control.
As waltr mentioned, this could be converted (with some loss) to a higher voltage (and lower current).
Pay attention to the max. temps of both hot and cold sides if you proceed.


If the subject is just heat to LED light, you may consider making a small steam engine driving a small stepper motor with either a capacitor (or a suitable NiMH battery) to make it DC'ish and some current regulation following that.

Is this purely for the learning experience or do you need the light(s)
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Melcin PowellTopic starter

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Re: Thermopiles
« Reply #10 on: January 11, 2011, 12:49:38 PM »
More for a Learning experience but it would be nice to have the lights.

Offline Soeren

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Re: Thermopiles
« Reply #11 on: January 12, 2011, 09:47:50 PM »
Hi,

What about a head band LED lamp for when you need light?

Most of them are fairly dim (I have bought many different types over the years and they have all been disappointing), but about 18 month ago I got me a "LED Lenser" putting out more light than I ever need (I only run it on max when the batteries are close to dead) and I have used it for work outside in total darkness as well as in dim areas like under kitchen sink cupboards etc.
It has a dimmer and is amazingly lean on the batteries (3xAAA) which is placed at the back, opposite the lamp.

What really sets it apart from most other head lamps are the very even and focus-able beam core (difference between narrow and wide beam is around 1:4) and the 170 lumen of light it puts out at the max setting. A brilliant lamp in several ways.

I think it's that one, although mine is grey in the accent on the head band instead of orange.

There are cheaper copies. I bought one about half a year ago (as a cheap backup) that looked exactly like it, but it have no beam adjuster and the light beam is not even like the original, but it was only about 1/4 the price.

Such a lamp will enable you to get your steaks (or shrimps) perfectly done, as well as help you not burning your pinkies when experimenting with heat to electricity conversion  ;D
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline madsci1016

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Re: Thermopiles
« Reply #12 on: January 13, 2011, 08:33:51 AM »
Hi,
What about a head band LED lamp for when you need light?

I see your sensible head band and raise you a stylish Red Neck version.





Offline Soeren

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Re: Thermopiles
« Reply #13 on: January 13, 2011, 04:17:08 PM »
Hi,

I see your sensible head band and raise you a stylish Red Neck version.
Oh, I've already broken 3 or 4 of those (different models, all of them somewhat wider), some of them have been fair (considering they ran from a couple of CR2032's), but their (plastic) attachment clips isn't really made for a cap (even though they're called cap lights).
As long as they keep together, they're OK and and I always kept an old beaten cap with a lamp on, as it's nice to just slam it on, have the hands free and the light where you need it. I used them very much until I got the Lenser and was happy with them (until I saw the light ;D)

A hybrid might be good - 1..3W in a cap with AA cells and electronics placed balanced around the rim.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline madsci1016

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Re: Thermopiles
« Reply #14 on: January 13, 2011, 04:29:36 PM »
The hat pictured is a 'hybrid', the LEDs are sown into the fabric of the bill, and the battery compartment is tucked inside around the band of the hat.

My brother got one for Christmas. That's why I thought of it when I saw this post. 

Offline Soeren

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Re: Thermopiles
« Reply #15 on: January 15, 2011, 10:13:42 AM »
Hi,

[...] the LEDs are sown into the fabric of the bill, and the battery compartment is tucked inside around the band of the hat.
I probably sound stupid now (just trying to learn), is the "bill" the proper name for the part sticking out (which in Danish is called the "shadow" translated).

Oh, I just have to get a cheap cap for experimenting now  :)


My brother got one for Christmas. That's why I thought of it when I saw this post. 
Nice, much better than the ones I have seen previously.

I'll post results and modus operandi here, when I get around to try it out.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline waltr

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Re: Thermopiles
« Reply #16 on: January 15, 2011, 10:25:23 AM »
Hi,

[...] the LEDs are sown into the fabric of the bill, and the battery compartment is tucked inside around the band of the hat.
I probably sound stupid now (just trying to learn), is the "bill" the proper name for the part sticking out (which in Danish is called the "shadow" translated).


Not stupid.
Yes, we do call that part of the hat a bill, like a duck's bill. This is only for that style of hat.

Us Americans still have a difficult time with British terms for many items so we don't expect these to translate to other languages.

Offline Soeren

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Re: Thermopiles
« Reply #17 on: January 16, 2011, 10:22:18 AM »
Hi,

Yes, we do call that part of the hat a bill, like a duck's bill. This is only for that style of hat.
Thanks waltr!
Now I just wonder why you named a ducks beak after a hat  :P  ;D


Us Americans still have a difficult time with British terms for many items so we don't expect these to translate to other languages.
Yeah, not all can be translated litterally. Just take a word like (having an) "issue", the closest thing is considered to be "problem", which it doesn't have to be, but we don't have a direct Danish word for it (well, that's the same in British language of course).
Well, it wouldn't be fun if it was too easy :)
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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