DIY plants growbox, PIC timer, 20W LED light

Discussion in 'The Projects Forum' started by takao21203, Jan 22, 2013.

  1. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
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    This is a complete project.

    -Schematic
    -Pictures
    -Source code
    -It was actually built + works

    It is a LED light growbox made from 2x Calypso Clear boxes. You could use any kind of cardboard box.

    There are various growkits for sale here for low prices, one of which I pictured. These plants typically grow in 2 or 3 months. No plants really like 24 hours light, so you need a timer. Or you need to switch it on/off manually.

    -You can place this box on your desktop or at work, maybe there is not enough light to grow plants. And it will be enclosed as well.

    -1x white 10W light + 1x red 10W light. A 12V 3A power supply is used. The LEDs have VGA coolers each. They don't turn so hot, the cardboard is not a problem. No screws of any kind are used.

    -The timer is based on a PIC 16f1824 but does not really need 4K space. You could use a different chip. A MOSFET is used to switch on/off the LEDs, and it works pretty well, does not heat up much.

    -The PIC is powered by a 78L05 and it also does not heat up much. Some 1uF capacitors are added but you could use any.

    -Two pushbuttons to set the time, the on-time, and the duration. The time is displayed as hours, 120 second minutes, and 2-second seconds, in binary!

    -The mode button will cycle through: Set hours, minutes, on-hours, on-minutes, duration hours, duration minutes, and reset.

    -The set button will cycle through from 0 to 31.

    -A 32 KHz crystal is used as timebase.

    -If there was a power surge, the timer actually will not turn on at all, so you have to check the display sometimes.

    -Total costs are about 30 dollar but can depend, it will be higher if you don't have all the materials available. This includes everything!

    -The timer just hangs outside the box but can be secured with some bell wire if neccessary. The wires inside are tagged a little with staples.

    -I have made a test run. The LEDs work fine and don't overheat. The timer switched on at the programmed time, and off again after the programmed duration elapsed.

    -If you build many of these, probably you can build them for less than $30. Yes I know a science laboratory needs $300 for the lamp, and another $200 for the box, and another $200 for the timer and power supply, as well $200 labour costs.

    Makes 900 dollar, so if you want 20 boxes, this is going to be expensive research.

    It is true if there is a power surge, the programmed time is lost, and the experiment will be ruined :)

    Actually the reason why I have built it was to show it on the internet. You can make a better PCB perhaps, or use some different display. I also use different displays, LCDs, LED 7seg, and I use real timers from a shop.

    But the circuit is quite useful, you can use it for just some minutes, or you could modify the program. Then you can switch on/off every few minutes or something like this.

    I have chosen a bit of an odd display so if you use it for college your instructor will wonder. As well the schematic is very specific so you need to redraw it. The C source is not commented but if you don't understand how the timer works, it can not be helped for now.

    By the way "It can not be helped" is a well known expression in japanese language.
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    There are several problems with this project. I have approved it so you may edit and bring it up to snuff. A proper schematic would help, the point is we are after clarity on the presentations. It is important.

    If you insist on running LEDs without current limiting I will disqualify this project, and move it to the Projects Forum. We have argued this point before, you are free to disagree, but in this my opinion rules. It is possible you have not drawn what I am looking for in the schematic.

    If the project is approved I will remove this post.

    Edit:

    The moderators are currently having a policy discussion on this thread.
     
    Last edited: Jan 30, 2013
  3. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
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    Here also the firmware for the PIC.

    If you wish to use a LED driver, this is also possible and makes little difference to the circuit.

    I don't have a better schematic.
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    Then it does not meet the requirements, as I said, you have a chance to edit. You still do, but this project does not meet the minimum standards for the Completed Projects Forum yet, and will be moved accordingly.
     
  5. GRNDPNDR

    Member

    Mar 1, 2012
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    7
    I'm a little lost on the diagram myself, I'd be willing to draw it up, but I don't know what some of the things are....like where it says 12V ... is that a battery?
     
  6. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
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    It's a 12V electronic transformer.
     
  7. MMcLaren

    Well-Known Member

    Feb 14, 2010
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    Not sure if this is would be of any help to anyone but I took the OP's program which was spread out across seven different files and combined it into a single 200 line source file which will compile in XC8. Unfortunately, the program lacks any meaningful comments.
     
  8. t06afre

    AAC Fanatic!

    May 11, 2009
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    Actually Bill, given that the OP use a 74164 or 74LS164 connecting a LED directly to a TTL output is quite possible. It will not harm the chip or the LED. Of course the output will not be valid as a logic output at the same time. Of course it is also considerations like the chip maximum ICC supply current. But one LED at a time in shift register will still be OK
     
    Last edited: Jan 31, 2013
  9. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
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    It is not so bad- the 78L05 heats up a little from 12V, but not that much. So the average currents is well within the limits of the 78L05.

    Maybe I could add some comments to the single source file which was produced.

    The plants of course grow but it looks they are stretching a bit from the white light. I will build another box like that with a 20W red and a 10W blue LED.
     
  10. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    yes they are stretching for sure.. With proper lighting they should NOT fall down. 20W of LED is NOT sufficient for decent plant growth.. more like 50W is needed. IMO
    Have you measured soil/plant height temps inside the grow box with the LED's either? IDK why anyone would put them into a box like that.

    Not to mention spectrum makes a big difference.. You haven't listed the spectrum of either LED you used. Should be like 660nm red and 455nm blues (something like that should work excellent)

    Then also lining the inside of the "hot box" with mylar will really help too.
     
  11. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
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    It is a pure white LED + one fake 660nm LED.
    They actually don't emit 660nm, I have compared them to 660nm LEDs.

    On order 1x20W 660nm, and 1x10W royal blue, for a better grow box.

    There is not much heat inside the box. The VGA coolers give a good airflow. I have watered today for the first time since I started the project.
     
  12. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    So you have a spectrum analyzer?

    And "pure white" is a marketing term.. Not an engineering one. (of course so is "not much heat") :p

    But yes LED's marketed as "royal blue" is typically in the proper bllue spectrum.
     
  13. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
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    The deviation is quite obvious. The fake red LEDs are almost the same as regular red LEDs, while the 660nm LED color tone is much deeper.

    I have understood "pure white" is a phosphor mix like cold white or warm white. Actually the white LED here is cold white- the one from my PC. So interestingly, it is not even "pure white".

    This may explain the stretching. Pure white is supposed to contain more red and yellow colors than cool white.
     
  14. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
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    Another picture from the box.
     
  15. tshuck

    Well-Known Member

    Oct 18, 2012
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    I think I'm done, but I can't be sure as the dang control unit is in the way...

    Also, I think I may have cheated on the maze:(
    [​IMG]

    This is a fun project...

    In all honesty, I like seeing other electronics personnel working on growing plants indoors... I grow Ghost Peppers in mine:D
     
  16. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
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    I am using it as desktop lamp now, the 50Hz fixture actually broke down some hours ago.

    I will be getting better LEDs soon: 20W 660nm + 10W royal blue.

    I will use them for my pineapple plant eventually.

    However, I will again need such a timer.
    Maybe I use a ready-made LED matrix this time :)

    2x 74hc164 is actually not so good. I will use 1x 74164+ 1x 74hc595 for the new timer.

    Or one of my LED display PCBs (these are a few years old with a powerless 16f716). I have one setup to drive a 5x5 matrix actually. So I think I will use this one. It does not have 32 KHz crystal but I hope it can be added.
     
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