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A little basic help please

Discussion in 'Renewable Energy' started by browningbuck, Dec 1, 2009.

  1. browningbuck

    browningbuck New Member

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    well Audio, judging by the name, you may be able to help me.

    im runing a lm4881n, and all the sudden its sounding very digital and distorted, lack of sound on some areas.... should i just get a new amp and see if i may have shorted a wire while putting all this together? or do you have another idea?
    [​IMG]
     
    Last edited: Dec 5, 2009
  2. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The LM4881 has a very low output power of only 0.2W per channel into 8 ohms. A cheap clock radio has more than double the power.
    Try replacing the IC if you want.
     
  3. browningbuck

    browningbuck New Member

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    Output wasn't the goal on this, not to mention this amp is more my level :) ... Anyway I'll try and replace and see if it fixes anything.
     
  4. dave

    Dave New Member

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  5. summitville

    summitville Member

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    browningbuck,
    Precision 15V 1W +/-1% Zener may be available here ...
    American Micro Semiconductor — Semiconductor Tutorials
    Part # 1N4744D (The "D" means 1% precision)

    Or you can replace the 15V Zener with a LM431 here ...
    LM431 - Adjustable Precision Zener Shunt Regulator
    I think R1 = 10K & R2 = 1K would work
    Adjust R1 to limit the Fully Charged A123 to 14.4 V when in Full Sunlight

    I like the LM431 better since you can simply adjust R1 to tune the "Fully Charged Cut-Off Voltage" to whatever works best for your A123 Battery.

    Prototype and let us now what happens.
     
  6. browningbuck

    browningbuck New Member

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    EDIT: read before i type :)

    and this seems like a REALLY simple design, EXACTLY what i was looking for. will get the thing built tonight. project was put on hold over the weekend due to the crappy amp out put. hopfully i can bring her back to life again

    testing of the solar panel on another set of A123 cells has produced better than thought results, this above discribed circuit will be required i think
     
    Last edited: Dec 7, 2009
  7. browningbuck

    browningbuck New Member

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    okay a bit more research and i am not sure if the LM431 by its self would do what we need? it has no dump mosfet :(.

    anyway i am getting kinda close on my dead line (box has to be complete by tomorrow)

    sooo i guess i may go manual control over the charging system since i dont think ill be able to figure out the requirments (ill pick up a 431 today, so that i am ready if some explains to me that this would work) just so you understand what i dont understand( i dont see where the circuit openes to stop charging once Ref is reached)

    [​IMG]
     
    Last edited: Dec 7, 2009
  8. browningbuck

    browningbuck New Member

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    this seems like, it would dump the energy, but man i dont think i can do all the cals on what i need in there by tomorrow :(

    [​IMG]
     
    Last edited: Dec 7, 2009
  9. browningbuck

    browningbuck New Member

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    ohhh maybe i can do this??
    this would do 14V

    D1 1N4007
    R1, R2 3.3K
    ZD1, ZD2 5.1V
    RX 100K
    R3 51K
    R4 130 ohms
    R5 8.1K or 8.2K
    ZM ZM33064
    N-fet 2N7000
    P-fet BSS92

    but not sure what C is ?


    ehhh i just dont think im going to be able to do it
     
    Last edited: Dec 7, 2009
  10. spindrah

    spindrah New Member

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    WTF :0

    [​IMG][/QUOTE]
     
  11. browningbuck

    browningbuck New Member

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    basically it dumps the charge off the panel on to the Nfet rather than over charging the battery
     
    Last edited: Dec 7, 2009
  12. browningbuck

    browningbuck New Member

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    wait i think this is the application Summit was thinking of witht he LM431
    [​IMG]

    not really sure what NPN or what the unlabled resistors or cap would be?
     
    Last edited: Dec 7, 2009
  13. summitville

    summitville Member

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    browningbuck, Just substitute the LM431, R1 and R2 for the 15V Zener component. I am tying to keep this as simple as possible. Unless you have upgraded your 34ma Solar Panel why do you need a Dump Mosfet for 34ma? The LM431 is rate 3/4W which is cutting it very close. But, I doubt you will even get 34ma at 15 volts from your 12v Solar Panel.

    Down the road if you really need to shunt more amps then you can use something similar to (but not exactly like) the ShuntRegLM431 diagram.

    OK ?
     

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    Last edited: Dec 7, 2009
  14. summitville

    summitville Member

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    browngbuck, Attached is an outline of a "Cell Balancing" Circuit for the 4S A123 Battery Pack. After you get your Solar Charger completed and you use it for a while you may find that one cell is "lazy". You cannot fix this problem (as discussed earlier) with a Series Charger. This circuit will re-balance all of the cells to within 1/100 of Volt !!! You could even attach the Balancer while your Solar Cell is charging the 4S A123 Pack. The Balancer circuit needs to be removed when the A123 Cells are balanced since the Op-Amps will continuously drain power from the batteries. A123's have low leakage (long shelf life) when disconnected.
     

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  15. spindrah

    spindrah New Member

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    BB just to help you on something else, when you draw a schimatic don't draw little bridges over wires, to indicate "no connection", like you have, instead draw a little circle. also draw the circle at your T's
     
  16. browningbuck

    browningbuck New Member

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    sorry spindrah, i cant take credit for those drawings.... they were copied off websites :(


    okay guys here is what i finished up last night, my plane leave tomorrow and this is a gift for my dad who is the guy who has everything, it is very much into energy and i thought this was kinda right up his road . like i said its a man toy and it will most likely sit on a desk, so the charging system is wired in to the Power switch and then cell monitoring is on the voltage switch that cycles through with the first number being the cell and the next three being the cells voltage. i know im gunna get flamed for the HHO system, but its just a toy and HHO has some good potential energy(the generator still has all the acrylic protection film on it ) thats why it looks brown. was able to fix the little amp, that powers two speakers. anyway thanks for all your help, i WILL be building the Shunt and adding it in on my next visit in June (but due to time, i will not be able to finish it at the moment, but hes smart enough to run the system where it wont hit critical voltages
     

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    Last edited: Dec 8, 2009
  17. Oznog

    Oznog Active Member

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    This will not work.
    For one, 12v is not enough voltage to charge 4x A123 cells. 3V per cell is almost dead.
    But the real problem here is the that any boost converter like this designed for a fixed-voltage input will fail on a variable-current-output supply like a solar panel. It will easily fall into an effect where it draws too much current and lowers the panel voltage below the MPP, then to try to generate 12V out from a lower Vin it will increase the current, dropping the Vin lower. It will latch into a state where Vin is very low and produce no significant output.
     

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