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Need some electronic add-on ideas for my new project (Stirling engine)


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hello daza long time no hear. i to have the details to biuld the stirling engine to , you can use the counters from out of a cassette player i think as youll only need to modify it to turn a small wheel and run a band from it to the cassette counter , thats one idea , as for turning a generator get one thats easy to turn not to high in tourqe otherwise you would have to biuld it on a larger scale to be able to turn a generator, once youve modified it , use all the plastic cogs and shafts you can find from dismantled video recorders they would be of use and even the mbushes from the motors in some microwave ovens. to

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Hi steven, and thanks for your reply :).

Yes that's a good idea for a counter :D, I'll have to have a hunt around to see if I can find one.  I have scavenge the electronic components from a couple of video recorders, but unfortunately that's all I kept, the electronic components :(.  I guess it's time for a trip to the scrapyard ;).

Steven, have you had any experience in using an electric motor as a generator?  I would expect that some would work better than others.

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Hi audioguru and thanks for your reply :)

That's not very optimistic Audioguru ;D ;D, I thought you were very good at making a project run on very little power, like your 3V LED Chaser project 8) ;D.

Sure I can add a few more candles and I can improve its efficiency ;), it's still early days  ;D. I'm in my comfort zone with this project to the point of adding a generator to power an electronic device, then it becomes a little more difficult for me :o.  That's why I'm asking the electronic experts for advice on the best way to generate power from this Stirling engine as well as a nice project to be powered from it.

The short of it is, I want to produce a very efficient model Stirling engine, and demonstrate its efficiency by powering an electronic device from it, I have little confidence of achieving good efficiency on the electronic side of this project, but I do have a lot of confidence of achieving good efficiency for the mechanical engineering side.

you could say this is my area of expertise although I have no qualifications, but I do have many years of experience in various kinds of mechanical engineering and construction ;).

I would appreciate some nice low-power projects ideas that could be powered by the Stirling engine, but the first step would be some ideas of an efficient generator of some sort.

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Hi Dazza

from the web searches I've done on the Stirling engine, it looks like it's the bees knees and someday might even replace the current internal combustion engine  :o

You could try starting with a very very small motor acting as a generator and use it to light a LED, whilst not very inspiring it will give you an idea of how much power you are actually generating from your temperature difference, you could then set up a solar cell as a comparison (I'm thinking of a tug-o-war) and experiment with different heat sources to find out the best way of driving the beast and then see if it can be scaled up/down and maintain efficiency.

Hope this helps

Ed

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Hi EdwardM :),

Yes, I do believe the Stirling engine will play a big role in our future energy needs, but I don't believe it will replace the internal combustion engine. it's a fare bet that the internal combustion engine will be fuelled via hydrogen in the near future ;), it has already been done and it was done as early as the Seventies 8)( http://www.rexresearch.com/hyfuel/ybrown/4014777.htm )

Thanks for the advice/suggestions EdwardM :D, that might be the best way to go to get started, use a very small motor as a generator to power some LEDs and see how the engine handles it.

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Hi Dazza,
I'm sorry to be so pestimistic but 1 candle power isn't much power.
I don't think it has enough power to drive an ordinary motor for its use as a DC generator. Maybe a very low-power electric motor for a school solar-cell spinning fan project might provide the low amount of drag that is required.
I think it would need gears or belt-drive to step-up its RPM so that it can produce enough voltage (1.8V) to light a red LED.

My pestimisticism (sp?) is because another member tried using a computer fan as a generator on his bike. With the fan spinning at a high RPM in the wind caused by him riding very fast downhill, it barely lighted a single LED (he wanted many LEDs to be lit and charge his batteries too!). When he connected the LED, the fan slowed down. So maybe the generator should charge a big cap at a low current, and have a Schmitt-trigger discharge the cap into an LED for a brief flash every couple of seconds.

LCD calculators use a very low voltage and current. Maybe you could make a 74HCxx oscillator (in my chasers they work with a supply lower than 1.25V at a very low current) and it can "push" the button contacts of the calculator. ;D

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Hi Dazza

Yes that's a good idea using a solar cell as a comparison Cheesy, but I am not too sure what you mean by (I'm thinking of a tug-o-war).


It's an allusion to a game where two teams of hefty blokes pull in opposite directions on a rope, the winner being the team which pulls the other team beyond a set position.  :D

I was thinking of something like a galvanometer/meter or something where it would be immediately clear which team (Stirling v Photocell) was winning and by how much

Ed
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Hi Ed, That's a good idea. ;D
You could have them each drive a solar-cell fan motor and their shafts could be connected to a belt, to show motion and point to the winner in the "tug-of-war" contest.

If one is much stronger than the other, the weakest will be pulled in reverse. :o

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Hi audioguru

maybe we could take the temperature differential between Canada and Oz as the input for a slightly larger Stirling engine  8)

Coz last time I was in Canada my eyeballs froze (Belle Isle Strait, December) and every time in Oz, even the occasional rain was warm  ;D

Ed

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Hi Ed,
Are you down under too? There are many of you upside-down folks on this forum. ;D
Isn't Oz closer to the South Pole than I am to the North Pole? ???

Just think of the huge tempersture increase in the center of our planet right in between us.
It would be more than enough to run a Sterling engine. ;D

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Guest Alun

I'm from England too, Bromham a village near Bedford to be exact.

audioguru,
PC fans won't be any good as generators because they are brushless and contain a small blocking oscilator that drivea an stator in the middle  a ring magnet is placed around this to which the fan blades are connected. When you were using it as a generator there were large voltage drops internally caused by the semiconductors in the driver circuit.

A small DC motor brushes from a an old CD-ROM draw works very well as a generator, some 12V remote controll car motors are good too. As a general rule I've found DC motors with brushes (given the correct load) generate electricity with exactly the same efficency as the do convert it to mechanical energy.

I agree though one candle power isn't that much if your candle outputs about 50 watts (Here is says 20 watts to about 111W)  of heat energy and I bet you your stirling engine is  getting less than a watt if you're very lucky and they'll be losses in the generator so you'll probably end up with a few mW of electrical energy there are still circuits you can run of this very low power level. I think in general the hotter the heat source the higher the efficency so try using your gas stove as the output will be several kW. ;D

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Hi all, and thanks for your replies :),

I am very sorry but I am a little short on time to properly respond tonight :(, but I will tomorrow night and I will provide pics of my Stirling engine or maybe even a short video clip ;), that is if I get the time to replace the diaphram which has failed, and of course just four you hotwaterwizard I will provide the design plans I used and further information on the principle of operation of the Stirling engine ;D.

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Hi Alun,
Yeah, I know. I've changed my profile's clock settings from Greek time to Californian time and now to my own time each time our server is moved.

Did you change your clock to Australian time so that you could post your crummy looking PNG?
Nya, Nya! My GIF looks much better and uses fewer bits too. ;D ;D

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Hi Dazza,

You need a well balanced lightweight flywheel with some small magnets evenly attached around it. Then make and fit some fixed coils close to the sides of the flywheel, put some load on the coils and you will soon find out how much load it can carry before it stops dead in its tracks. ;D ;D

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Guest Alun

Did you change your clock to Australian time so that you could post your crummy looking PNG?


PNGs are better they're 16 million colours while with gifs you're restricted to 256 and they take up less space too. :D

Nya, Nya! My GIF looks much better and uses fewer bits too. ;D ;D

Click on the paper clip next to the image to get a better view or if you're cool and use FireFox right click and go to view image. ;D
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Guest Alun

In fact PNG comes in two flavours, PNG-8 which is limited to 256 colours like a GIF, and PNG-24 which can store up to 224 (16.7 million colours). In general PNGs are smaller than GIFs but the only disadvantage is they can'r be animated but there's shockwave media flash for this so the GIF really is obsolete in my opinion.

Here are some links on image formats:
http://www.webopedia.com/DidYouKnow/Internet/2002/JPG_GIF_PNG.asp
http://www.yourhtmlsource.com/images/fileformats.html
http://www.sitepoint.com/article/gif-jpg-png-whats-difference
http://searchwebservices.techtarget.com/sDefinition/0,,sid26_gci214307,00.html

Here's and anti-gif site: http://burnallgifs.org/

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