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661  Using Arduino / Project Guidance / Re: Controlling Motors and Heaters on: November 20, 2011, 05:38:04 pm
In the "third world" very little goes to waste. Most things are re-used. This would include, for example, dentures which you can buy second hand (mouth) in the market. Lathes are often extremely skillfully powered using a bow with the blade being operated by foot, 1kw is usually not readily available. Go to a place where plastic bags are returned grab a random handful. How are those bags, some of which will be old, wet dirty and full of holes, be fed into your system?

I don't wish to be critical of your idea because you have given little information about it but I think you yourselves need to take an objective look at its practicality.

662  Using Arduino / Project Guidance / Re: Controlling Motors and Heaters on: November 20, 2011, 05:14:38 pm
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We are designing a machine that will take used plastic shopping bags and draw them through a heated section to seal the outsides making a "packet" of bags.  If it is thinner it can be used as padding or even molded into a shape, if its thicker it can be used for insulation.  The hope is to create an automated process that will reuse some of the wasted plastic in the world. 

So how do people recycle plastic bags at the moment and what is your improvement upon this?
Have you done any kind of energy balance calculations to work out what your energy saving will be?
663  Using Arduino / Project Guidance / Re: 2 Stage Model Rocket feasibility on: November 20, 2011, 05:06:05 pm
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I don't imagine any well-built Arduino would be troubled by the sort of accelerations likely to be encountered by amateur rockets, assuming all connections are soldered.
saulton7 seems to know what he is about but he also has budget considerations. My rocket attempts were all pretty terminal affairs, with people suggesting home made gunpowder I guess they have had similar experiences.  smiley-evil
I would be concerned not so much about about the board itself but how it was mounted, whether or not it would short and if/how it was protected from engine failure.
664  Using Arduino / Project Guidance / Re: 2 Stage Model Rocket feasibility on: November 20, 2011, 04:22:36 pm
I don't know about you but I cannot afford to kill my arduino. Since you just got it for your your birthday I guess you are going to try try not to blow it up, so how are you going to protect and recover it?

What is are your targets for payload and altitude, and what will the maximum g force be?
 
665  Using Arduino / Project Guidance / Re: Digital air conditioner control for daily car, possible with arduino ? on: November 20, 2011, 04:08:20 pm
I agree with PeterH, when you say
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I want to convert it to digital with using arduino.
that suggests you want to change rather than replace the existing system, and the manual systems are clunky and need a lot of force. It would probably help people if you said what your mechanical and electrical skill levels are and what sort of tools you have available.

Could an arduino control air conditioning - yes.
However there could be a lot of work involved, much more than just moving the lever up and down by hand, so is this for fun?

666  Using Arduino / Project Guidance / Re: MIDI/Motion sensor harness to make music while dancing. on: November 17, 2011, 05:06:04 pm
They seemed to be using a three wire system, which ties in with this and my guess;

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Electromyograph

An electromyograph (EMG) uses surface electrodes to detect muscle action potentials from underlying skeletal muscles that initiate muscle contraction. Clinicians record the surface electromyogram (SEMG) using one or more active electrodes that are placed over a target muscle and a reference electrode that is placed within six inches of either active. The SEMG is measured in microvolts (millionths of a volt).[6][7]

This article gives detail on EMG
http://edge.rit.edu/edge/P08027/public/IRB/Papers/intro_EMG.pdf

I suppose a first step would be to try and find an electrodes at a reasonable price and then some way of amplifying the signal.

The video clip seems to be advertising so it is also worth considering how much was "real" and also what was spent.
667  Using Arduino / Project Guidance / Re: MIDI/Motion sensor harness to make music while dancing. on: November 17, 2011, 04:36:53 pm
I am not sure he is using motion sensors. Possibly he is detecting electrical impulses to muscles or changing resistance as muscles move? Great idea. I don't think you need to worry about the midi part or the wireless communications, those problems can solved, the question is how to get signals a dancer can control by body movement.
668  Using Arduino / Project Guidance / Re: I Just bought my first Arduino!! yay!! on: November 17, 2011, 04:14:19 pm
I was expecting images of ghost animals by now  smiley-evil
669  Using Arduino / Project Guidance / Re: Infrared distance sensor through glass? on: November 17, 2011, 03:58:56 pm
I suspect that the glass will reflect the infrared so the sensor will always read the distance to the glass.
This article agrees with my practical experience;
http://answers.yahoo.com/question/index?qid=20081001100003AAH2Ouo

You are not really interested in "distance" though since paper on the table will always be at the same distance.
As suggested by PaulS you might be better looking for a drop in light level. Can you not always have an external light source then have a light sensor under each hole.

You have my curiosity, why are you taking pictures inside a box when holes are covered in paper?   smiley-kitty
670  Using Arduino / Project Guidance / Re: Need advice for first purchase. on: November 16, 2011, 04:01:09 pm
I was pleased with this kit, which may be the same as your second link certainly the booklet cover is the same;
http://www.oomlout.com/a/products/ardx/

As other people have said you could save money buying bits. However I thought it was worth the extra to get a "package" deal. When you are learning knowing that something should work makes it much easier to find your programming or wiring fault. If I had bought the bits my concern would have been that I had got the wrong spec. parts ad so on.

The motor and servo in the kit are just toys but they get the principles across.

I would also advise you to download Fritzing it is free at http://fritzing.org/. Fritzing seems to provoke some strong reactions in the forum. If you have no other package though it is a good way to be able to communicate your schematics and designs - which is essential if you have problems and want people to help.
671  Using Arduino / Project Guidance / Re: Solar Tracker on: November 15, 2011, 02:52:06 pm
I agree with robtillaart you need to avoid tracking the brightest part of the sky, rather than the sun, as you may waste more than you save. Also depending on what you want to achieve there may be simpler cheaper ways of getting 90% of the result. The maximum height of the sun in the sky changes through the year. You could put solar panels on a board whose angle was manually changed say once a week or month to a setting appropriate for the time of year.

Here is a site with lots of ideas for trackers from cardboard (must be sunny!!!) to clockwork, there are a couple of arduino based solutions as well.
http://www.instructables.com/tag/?sort=none&limit%3Atype%3Aid=on&limit%3Atype%3Acomment=on&limit%3Atype%3Auser=on&limit%3Atype%3Agroup=on&limit%3Atype%3AforumTopic=on&limit%3Atype%3AforumComment=on&limit%3Atype%3Aquestion=on&q=+sun+tracker

There is also a program that states;
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Calculates position of sun in sky, as azimuth (compass bearing
' measured clockwise from True North) and angle of elevation, as
' seen from any place on earth, on any date and any time.
' Also calculates alignment of a heliostat mirror.
672  Using Arduino / Project Guidance / Re: DESKTOP CNC Idea on: November 14, 2011, 04:59:21 pm
Take a look as this excellent project by Grumpy_Mike.
http://www.thebox.myzen.co.uk/Hardware/CNC_Conversion.html

673  Using Arduino / Project Guidance / Re: RS485 and commercial scrolling LED board on: November 14, 2011, 04:29:08 pm
RS232 is single ended and used for point to point communications over short distances. RS485 is a differential signal that can be used for multi-drop and over much longer distances. You cannot simply plug RS232 into RS485, you need a converter.
674  Using Arduino / Project Guidance / Re: creating a cyborg fish need some assisstance. on: November 14, 2011, 03:41:02 pm
The bionic marlin.
The chub men.
Darth viperfish.
675  Using Arduino / Project Guidance / Re: Several Things about an High Altitude Balloon on: November 14, 2011, 02:57:46 pm
Would speed of sound experiments not be best done in a lab where you can control temperature, pressure, humidity and gas composition?

If you are going to do it using a balloon then it might still be an idea to prove the equipment in a lab e.g. put it in a bell jar, in a fridge, reduce the pressure and temperature to what is anticipated on the flight and prove that the equipment functions and the readings are meaningful.

Using the ultrasonic distance sensor sounds like a good idea. The human voice though changes pitch with ambient pressure so its possible the ultrasonic transmitter will also change frequency which might affect the measurements it takes - something to check.
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