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31  Using Arduino / Project Guidance / Re: Tracker Solar on: June 16, 2014, 11:33:29 am
So if you have GPS, you have the time, right?  The clock signal being broadcast by the satellite is atomic-based if I'm not mistaken, and will likely be way more accurate than your RTC.  Each satellite has been calibrated to the same time, and all they do is transmit an ID and the time continuously... I think?   Then the GPS receiver compares the time it took for each of the clock signals to come in and uses some trigonometry to determine your latitude and longitude.  I'm probably oversimplifying, but that's at least how I thought I understood how they work.

I mentioned the RTC as I was just going to use the GPS initially to get the position, enter it by hand and then take the GPS away.  Having an onboard GPS is a great addition.  The price of GPS modules with antenna have come down below $20 so adding a permanent one would not be a big issue.

With the proper equations and evaluation of the math using the GPS time stamp I doubt very much if the search method will beat it.  Also, you need to keep in mind that search/optimization routines can find local mins that many times are not close to the best solution.  I have done a lot of optimizations in a former career and was always anxious if I could not see the results.

wade
32  Using Arduino / Project Guidance / Re: Tracker Solar on: June 15, 2014, 10:57:21 am
There are equations that very accurately estimate the position of the sun based upon the tear, month, day, time and your location, by accurate I think the max error is under 0.5° probably better than a tracker will do.

With these well known equations why not put in an RTC so you know the time, and use a handheld GPS to get the location of the collector (a one time measurement).  Calculate the position of the sun and then just point to the sun, adjust every 5-10 minutes and sleep the rest of the time.  The lag time could be calculated beforee it "went to sleep" by

This method will provide at least as much accuracy and since the system is not always searching for the best situation the driving motors will last longer.
33  Community / Gigs and Collaborations / Re: Gig available: ultrasonic tank level indicator on: June 13, 2014, 07:19:30 pm
LKB,

I sent you a PM.

Thanks
wade
34  Using Arduino / Project Guidance / Re: i need help for my graduation project on: June 12, 2014, 01:59:51 pm
Doing degree completion for money could be disastrous because we would be unleashing completely unqualified engineers on the world and some of them will be designing things that could cause you harm.

With the internet and many documented  cases of plagiarism and cheating in school many students (the OP I am sure does not fall into this category) many engineering students have never been confronted with a problem that a million people have not already done, documented it put it on the web etc.  As I would tell my engineering students no one is going to pay you much money to answer questions that have already been asked.  The hardest problem assigned in your 4 years of class will be easier than a very simple project out in the field.
35  Using Arduino / Sensors / Re: IR reflectance sensor pendulum on: June 11, 2014, 03:40:46 pm
tape a narrow stick on the bottom of the bell and place a photo interrupter so that the stick blocks it as it passes by.

wade
36  Using Arduino / Project Guidance / Re: Help with rebuilding electric golf trolley. on: June 11, 2014, 03:38:00 pm
I personally would use a solid state relay as they have come down in price and controlling that much power is a trivial thing for an SSR as long as you use the spec'ed heat sink.  I may be a little biased but spending a little extra money and getting one a little oversized is a good thing.  It is hard for manufa, ctures to over spec things because they are making 100's, 1000's whatever and want to make as much profit as possible and compete, you are only doing one so you can overbuild it in places.

wade
37  Using Arduino / Project Guidance / Re: Help with Sound Sensor on: June 11, 2014, 08:30:00 am
If you want to amplify sound it will work.  You might want to state what you want to do before asking if it will work.

wade
38  Using Arduino / Project Guidance / Re: Positioning using NRF24L01+ radios? on: June 10, 2014, 09:46:57 am
Quote
If where to place out alot of NRF24L01+ on the racks could I then use a noter NRF24L01+ and arduino on the forks of the forklift to determine on what locator the forks are depending on the streanghts of the sorrunding radios?

Probably not. RF signal strength and distance measurement are really not reliable unless under very ideal conditions.

The advice you are getting is spot on, listen to it.

Maybe the way to do what you want is with RFID tags on the shelves.  The Forklift would have an RFID reader interfaced to an Arduino and the Arduino would be radio linked back to the display you monitor.  This would fail if the sizes of the shelves were too small so the RFID reader got signals from more than one shelf. 

Hope this helps,
wade
39  Community / Gigs and Collaborations / Re: Build us a cell-communication device that monitors a cabinet door on: June 09, 2014, 10:25:55 pm
It seems we did not inspire the OP with greatness go here http://jobs.arduinoexperts.com/jobs/cell-communication-device-to-send-an-http-request-or-text-msg-when-switched-on/.  I responded to him with a PM.

A pretty easy project that he wanted 50% solved in the proposal and then an interview in San Fransisco for a simple project.

Maybe his time is not expensive,
wade
40  Using Arduino / Project Guidance / Re: really need help guys ... my graduation project :( on: June 09, 2014, 09:42:27 pm
Well let's see you say you need to graduate, and you are asking for help and the manner in which you asked the question showed limited knowledge in RF wave propagation, Arduino programming and XBee configuration, it sounds like your total project.  The key is  you need to graduate yet, you are asking for us to do the bulk of the work for you.

I taught at the college level for 11 years here in the USA and on the bottom of the syllabus under the Terms and Conditions section was the following:  There are no extra points granted because you have to graduate, because YOU are the one who is supposed to do the work to graduate not receive extra points just because you have a job lined up after graduation.

If your method was to work why would the unknown location have to be within the confines of the box defined by the location of the 4 XBees, if you have this magic equation that converts RSSI values to distance the sender could be anywhere in proximity.  In fact if you have this magic equation you really only need 3 XBees so I have saved you some money to put against next year's tuition, no thanks needed.  Are you asking on another forum for a large RF anechoic chamber to test your system in, and yet another forum to carefully measure the sensitivity levels of each XBee?

You will have more fun in school than any other time of your life so enjoy the extra time you will be having.

wade
41  Community / Gigs and Collaborations / Re: Seeking Design and Prototype development for BBQ Temperature Controller on: June 09, 2014, 03:27:18 pm
You may want to start here http://www.ebay.com/itm/AC-110-120V-Digital-Temperature-Controller-Thermostat-F-fahrenheit-/140938285343?pt=LH_DefaultDomain_0&hash=item20d093911f.  You will need a thermocouple and either an solid state relay (electric grill), electric valve (gas) which you will need if you went with an Arduino.

I use one very similar on my smoker and my curing box.

wade
42  Using Arduino / Project Guidance / Re: Pest Repeller on: June 05, 2014, 01:42:51 pm
Neptunus,

The first and hardest part of the task is to find how to repel the mosquitoes in the first place and then see if arduino would be a good controller of that repelling method.

I know the US army has done a lot of research in reducing mosquitoes, as it reduces effectiveness if the troops don't get sleep mosquitoes carry pathogens with them at times, and they found the best solution was to use a CO2 generator that is driven by a liquid propane tank.  After the mosquitoes get attracted to the CO2 a slight vacuum suck them up into a reservoir where they are not a bother to the troops.  Occasionally you have to empty the reservoir and you are done.  I have one that I used to use outside my house before the trees grew up and supported birds and other eaters of mosquitoes.

Not a lot of help I know,
wade
43  Using Arduino / Project Guidance / Re: Graphic Overlay For Capacitive Touch Buttons on a PCB on: June 01, 2014, 07:08:52 pm
Well... inkjet printable vinyl sticker with a laminating clear sheet applied might be what you need. You need to make sure and get an inkjet printable vinyl that is compatible with your printer. IE, compatible with water based inkjet inks.

http://www.papilio.com/inkjet%20waterproof%20adhesive%20film%20media.html


This is exactly the route I decided to try I ordered the vinyl and clear oversheet from papilio, I placed the order about an hour before your post.  I will keep people aware of the progress.

Thanks to all who read and to those that responded with ideas.

wade
44  Using Arduino / Project Guidance / Re: Graphic Overlay For Capacitive Touch Buttons on a PCB on: June 01, 2014, 11:23:21 am
Thank you for the two responses, I appreciate them.

I should have included in my original post that I need a solid sheet not a transparent one as I want the solid color of the sheet to fully cover up the PCB.  In addition I should have included that this is for an outside un protected location for water soluble glue might not work the best.

Thanks Again,
wade

45  Using Arduino / Project Guidance / Graphic Overlay For Capacitive Touch Buttons on a PCB on: June 01, 2014, 10:37:52 am
I have purchased a capacitive touch panel from Sparkfun https://www.sparkfun.com/products/12017 and would like to find a plastic sheet that I could print with a laser or inkjet printer to use as an overlay for this panel.  Ideally, the sheet would have an adhesive on the back side, otherwise I would use glue that is acceptable to that application.  The overlay would have outlines and identifiers for the tough pads.

I have googled and looked on ebay and have been unable to find an appropriate material.  I imagine there is sheet material out there that is appropriate but I am probably not using the correct search terms.  So any help here would be great.

Thanks
wade
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