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Help needed (Solar Lamp Circuit)

Discussion in 'General Electronics Discussion' started by Rogueraven, May 18, 2013.

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  1. Rogueraven

    Rogueraven

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    May 18, 2013
    Hello

    I need help with a solar lamp circuit with dawn and dusk detection. I've posted this on other forums and got no help so here I am :)

    Firstly I do not have all the equipment required to make this project yet and the equipment I do is subject to change if required.

    What I want to do is take a 12v 10w solar panel the type used to trickle charge 12v car/trailers/caravan batteries, and use it to charge two 7.2v 3000mAh (6x1.2v AA) battery packs at C/10. The two battery pack will be used to power two lamps at two different locations, one battery pack per lamp. Also the solar panel needs to act as the switch Sun down lamps on, Sun rise lamps off charging begins.

    I've drawn out a basic diagram however I cannot enter the resistor values due to currently not owning the solar panel yet and not having the read outs, but can someone tell me if the first part of my circuit is valid. and if not draw a better solution :)


    Diode = 1N5391 / 1N5399 ?
    Voltage regulator = L7809cv
     

    Attached Files:

  2. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    652
    May 8, 2012
    NiCd, NiMH, else?

    Chris
     
  3. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    I forgot to mention that your title had me expecting something else. I thought it was a Solar Oven or grill! :p

    Chris
     
  4. Rogueraven

    Rogueraven

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    May 18, 2013
    I will be using NiMH, Solar Oven or Grill... maybe the next project
     
  5. duke37

    duke37

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    Jan 9, 2011
    Ewe mutton ram the point home!
     
  6. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
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    May 8, 2012
    I would think that a Constant Current Source (CCS) with full charge dropout or trickle charge mode would be in order. Considering that the cells will cycle every day full charge dropout should suffice.

    Chris
     
  7. Rogueraven

    Rogueraven

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    May 18, 2013
    I guess I should have mentioned I actually have no idea about electronics and are a complete beginner I'm slowly looking a circuit diagrams to expand my knowledge a little.

    CCS or Constant Current Source is a circuit that maintains a constant current? I do not know how to build one of these, I guess I should draw out the entire circuit diagram for the project then we can take it from there ?
     
  8. BobK

    BobK

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  9. Rogueraven

    Rogueraven

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    May 18, 2013
    So I take my solar panel, connect it to a CCS (LM317) device split it into two 9v outputs ?

    What I should do I guess is buy the solar panel, then from there have someone draw up the diagram for me to follow that way we have the panel specifications to start with ?
     
  10. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
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    May 8, 2012
    Keep in mind that 10W is a max value and equates to only 833mA @ 12V. This has to be shared with a storage battery and two 7,2V battery packs.

    Chris
     
  11. Rogueraven

    Rogueraven

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    May 18, 2013
    Maybe I should explain purpose, beings I have the mutton with a P bulbs already it would be better to explain purpose and given that 12v/10w and 12v/20w panels are roughly the same price you'd be better served to advise me :)

    The idea is to take two TTS-1WCREE (Red) bulbs, inserted into waterproof camping lamps which would be then hung from inside of two grow houses for chilli plants and tomato plants, these are small grow houses 3 plants each house just to get a idea. Chilli plants and Tomato plants must be kept apart hence the need for 2 lamps at different locations.

    The idea was to use the solar panel as the on/off switch like in the basic LED garden lights, however individual dawn/dusk sensors could also be attached.

    Using battery packs like I mention means I could keep them contained within the individual lamps, however I could easy fabricate another storage box for alternative power options, and beings this project seems to outstretched my basic knowledge of Electronics its best if I let you experts decide on the best options to proceed with this project
     
  12. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
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    Jan 21, 2010
    I see no reason not to plant tomatoes and chillies together.

    Two bulbs are not going to provide enough light to encourage a lot of growth.

    Full sunlight is around 1000W per square metre. Consider the power your lights need to have to get even a fraction of that.
     
  13. Rogueraven

    Rogueraven

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    May 18, 2013
    I'm not trying to mimic the sun and the lights are not to encourage growth so to speak, Tomatoes and chilli's are being kept separate due to being closely related plants and to rule out potential cross pollination.

    Do not want to take subject off topic :)
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Look at the circuit diagram of solar garden lights (I'd google "solar garden light schematic).

    In the interest of minimum parts count, they frequently use a lack of voltage from the solar panel to turn on the light.

    One way to do this is to have a diode in series with the panel (this also serves to prevent your battery discharging through the panel at night. The voltage from the panel serves also to hold a transistor off. When the voltage from the panel falls sufficiently (much lower than needed to charge the batteries) the transistor can turn on and this then enables the lights.

    This page does a good job of explaining how they work. In this case the solar panel holds a transistor on. When it switches off it allows the other one to oscillate. If you remove the components which cause oscillation, the transistor will simply act as a switch to turn the lights on.

    If your lights are of significant power, it may be better to have a 2 transistor schmitt trigger being turned on and off by the first transistor. This will mean the light turns on and off sharply. For higher powered LEDs this will prevent excessive dissipation in the switching transistor..
     
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