NEW HERE and very green

Discussion in 'General Electronics Chat' started by greenJames, Apr 24, 2013.

  1. greenJames

    Thread Starter Member

    Apr 24, 2013
    68
    3
    Hello all
    I thought I would Introduce myself

    I'm looking at starting to build a solar tracker for a summer project with my 12 year son.
    I know nothing about Electronics but that is not going to stop me.
    I have found a circuit diagram for a tracker and thats it, what do I need to do Help
    Last year I made with my son a CNC router with the help of a forum.
    I would like to cut my own PCB board but again not got a clue how to proceed
    Here is the circuit http://greentechtown.com/solar-tracker/ The only thing is I've bought a 24v Linear Actuator

    I live in the UK near Coventry

    I'm running to maplins tomorrow for the parts

    James
     
  2. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    Hi James, and that is a wonderful attitude! Welcome to the forum! :)

    To save people going to your external link, the circuit for that open-source solar tracker is shown here;
    http://www.greentechtown.com/images/solar_tracker_circuit.png

    It says it does not have a return to home after dark. I think that is a failing!

    Also it seems much too complex for my liking, and uses a messy h-bridge setup to drive the motor, which is a bit silly since it doesn't return to home after dark (ie the motor only needs to move forward when tracking)!

    There are a lot of other circuits on the internet, I would look for a much simpler one.

    OR, people here might want to suggest a circuit to you or help you design one.

    Personally I would try something like this;
    1. two photo sensors, slightly angled EAST/WEST by a few degrees.
    2. a simple comparator, if sensor WEST is brighter than sensor EAST, the motor runs forward.
    3. That only needs a single transistor or FET to drive the motor.
    4. When really dark (sensed by another comparator), a relay turns on, and runs the motor back to home, where a limit switch turns off the relay.

    Defining the operation like that in simple blocks is a good first design step. Then when you know what all the blocks do, it is easy to design the circuit for each small simple block. :)
     
    killivolt likes this.
  3. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    I like RB's idea. If you need help implementing it do ask.
     
  4. greenJames

    Thread Starter Member

    Apr 24, 2013
    68
    3
    I would love to have help Implementing it


    I'm going down to maplins for a bread board

    Ok I've bought a 24V DC LINEAR ACTUATOR from ebay to get me started what will I need to buy to start moving this I know I need LEDs and that's it.


    James
     
  5. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    LEDs as the two photo sensors? I've never tried that but have seen lots of examples. I don't think they are as sensitive as CDS sensors or little photocells.

    What is your power source? Is it a 24v battery?

    You will need something for the PSU like a 5v or 12v regulator and some caps. Then a relay, and transistor and diode to drive it. And a limit switch, like a lever type microswitch.

    For the comparator a LM311 or some common dual comparator will do, some resistors, trimpots, and something to drive the motor forward like a NPN power transistor or NFET.

    We need to know a bit about your linear actuator and final mechanical setup, like how much current it needs to move the solar panel. Personally I would have chosen a DC motor with built in wormdrive, like one of those "wheelchair" motor. A linear actuator will be a bit more complex in the way it rotates the panel.
     
  6. greenJames

    Thread Starter Member

    Apr 24, 2013
    68
    3
    RB I intend to use the actuator only for north and south movement and a geared motor for the East and West movement I have a golf trolley motor for this

    The power supply will come from two 12v battery's

    I'm going to make a small one first as a experiment.

    I've ordered a Arduino Uno R3 for my main tracker but a small tracker with LED's as a light sensor and then one with cds

    the small tracker is this one http://solartracker.greenwatts.info/solar_tracker_LM339.htm

    The larger tracker is going to be designed around this tracker http://www.binaryorbit.org/prototype1.asp

    I've bought LED's for the greenwatts project I think these are the right LED's
    ebay 330874982048

    James
     
  7. tobyw

    Member

    Mar 21, 2013
    37
    4
    Do you mean you want to make your own pcb from copper clad? I've recently been getting into this and had some good results using the free Eagle PCB software, photoresist board from Maplins, a UV unit, and ferric chloride.

    I'm not far from you - in Banbury. If you wanted to make use of my UV exposure unit, you would be more than welcome.
     
  8. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    Great! A golf trolley gearmotor is ideal.

    However for the N/S tracking it's often considered to be not necessary. Year round the differenIce is only 23' (if I remember right) so if you set the panle tilt at the average then winter summer error is only 11.5' max, and talking the panel away from the sun just 11 degrees will barely make any difference in the power output.

    Another alternative is just to put a N/S adjustment on the panel mount, and every 2 months or so you walk out to the panel and move the adjustment to compensate for season.

    That's a great idea, it will give you experience with the sensors and what to expect from the sensor output voltages etc.

    I would avoid the RC servo project, as experience with those won't help much with your final large tracker design.

    But that little Greenwatts board with the LM339 comparator and parts to drive a DC motor looks like a good starting point. :)
     
  9. greenJames

    Thread Starter Member

    Apr 24, 2013
    68
    3
    Thats a very kind offer but I wanted to cut a pcb out on my CNC router as it would cut all the relevant copper of the circuit board and drill all my component holes as well I could also turn it over and engrave all the parts as well

    However If this doesn't work out Yes please

    James
     
  10. Rbeckett

    Member

    Sep 3, 2010
    205
    32
    James,
    This is definately the place to learn about electronics and systems. I have been a member for a few days and can tell you that you are on the right path and all you need do is ask and someone will usually be glad to help you set something up. The part I like is that they dont just do it all for you, but guide you to the lessons you need to learn to be able to figure it out all by yourself. Much more satisfaction when you do it yourself and accomplish what you set out to do. And it doesnt take much longer to learn it than it would for someone to do it for you. Take your time and follow the hints that the memebrs give you and you will have a great journey to building the Solar Tracker you have dreamed up. Good luck and dont forget to post some pics when you get started and when you finish it too.

    Bob
     
  11. greenJames

    Thread Starter Member

    Apr 24, 2013
    68
    3
    Bob
    Thank you for the kind words of encouragement I have today Down loaded Eagle to start my circuit and then Its cutting on the CNC Machine.

    My Parts for this project have started to arrive in the post. I am getting excited now just the odd motor to source and on my way

    James
     
  12. greenJames

    Thread Starter Member

    Apr 24, 2013
    68
    3
    Just a small up date.

    most of my components have arrived this week. I'm going away for a long weekend (camping) however I have down loaded Eagle pcb software and some tutorial to my laptop some circuits will be designed (ok copied), with some luck I will have Gcode for my LM339 circuit ready for cutting out next week.

    wish me luck I will try and upload some photos of parts to-date.

    James and Luke

    O'yes nearly forgot I have bought Luke a Raspberry Pi.
    The excited young man went to the science and technological museum in London with his school, let just say he was inspired. Ive also dug out his robotic arm from Maplins to take away with us and build hes only had it two years. I do want him to run this robot off his PI to take to school for the summer fair ( just think a solar powered PI and robotic arm) cool every boy/Dads Dream..

    we will be taking this project one day at a time, together.

    again thank you for all help and support given James and Luke
     
  13. greenJames

    Thread Starter Member

    Apr 24, 2013
    68
    3
    here is the small up date of Items as of last Friday I will update with better images tomorrow when I can get to a tripod

    [​IMG]

    James
     
  14. Rbeckett

    Member

    Sep 3, 2010
    205
    32
    Lookin Good James. I started about the same way as you and over time I have built a huge selection of misc parts from off shore and Thai suppliers. I allot a monthly allowance and try to shop diligently and it is amazing how far you can stretch a few bucks. I kind of over did the budget and was spending about 50 bucks a month and I have all kinds of Chips, Adders, Multiplexers, Drivers, Op-Amps and transistors. I also have several different flavors of caps, resistors in varios watt ratings, Diode, LED's, 7 segment displays and connectors of every description and size. Build a little at a time and follow the text above from beginning to end and do the exercises and you will have a very stron basis for a degree or job in the field. I'm old and crippled, so I wont ever go back to work, but I can just sit down and build whatever comes to mind and rarely have to order a part to finish a project. So stick with it and be patient, the math gets easier especially once you have a basic understanding, and Bill and the Book Developers are usually here and will help you if you get stuck. Try to figger it out first, then ask for a hint and try to figger it out from there. It will make you so much better at it when you are all alone in the dark trying to figure out a problem...Dont get discouraged and give up before your miracle happens. Trust me it will happen sooner or later, it always does. Enjoy the rest of the week and the camping trip too.

    Bob
     
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