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 31 Using Arduino / Project Guidance / Re: Tracker Solar on: June 16, 2014, 11:33:29 am Quote from: Xpendable on June 16, 2014, 10:30:56 amSo 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.Thankswade
 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 from: zoomkat on June 10, 2014, 08:05:40 amQuoteIf 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