I need assistance, BAD!

Discussion in 'General Electronics Chat' started by Beach, Dec 10, 2013.

  1. Beach

    Thread Starter New Member

    Dec 10, 2013
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    This is a very general question, and im not quite sure what to even search for so please, dont flame me, i admit i am a super n00b.

    a project has been placed into my lap and im going to do my best to achieve desired results from my company.

    From start to finish i need a small circuit board, with some kind of chip that does a few simple things.

    It needs to have:

    a thermostat that is accurate
    exhaust and intake fans (pc fans will work)
    run a few simple led's
    turn on/off heating unit and or chiller at desired temps.

    i work for a programmer but he is insanely busy and he gave me this project to get into this side of the business.

    ANY help or guidance is GREATLY appreciated. even if its you guys telling what it is i need to read up on, what kind of programming would be used for my needs, and where to buy the parts i would need (minus the fans/leds)
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    Every design begins with an idea and a concept. There is a systematic approach to design.

    1) Define your product.
    Give it a name. What are the objectives? What does it do?

    2) A picture is worth a thousand words.
    Draw a block diagram that shows the major components. Leave out the details for the moment.

    3) Specifications, specifications, specifications.
    Quantify the parameters. Write down the numbers.

    "a thermostat that is accurate" means nothing.

    Define your temperature units, range, precision (how many decimal places?)
    and accuracy.

    For example 0.0 to 55.0°C +/- 0.1°C

    "thermostat" can mean a 101 things.
    What is your heat source and load? Heat capacity? Ramp up/down time?

    What is your supply voltage?... just for starters.
     
  3. #12

    Expert

    Nov 30, 2010
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    Just a few more questions...
    What is making the heat? What is making the cooling? How many kilowatts are involved? How much mass is slowing down the temperature changes? How accurate do you need to hold the temperature? Are you controlling the temperature or just measuring it? etc.
     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,290
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    Depending on the temperature a sensor like this should work:
    http://www.ti.com/lit/ds/symlink/lm35.pdf

    Then a comparator like this one:
    http://www.mouser.com/ds/2/149/LM339-186212.pdf

    And a voltage reference like this to compare the output of the sensor to.:
    http://www.ti.com/lit/ds/slvs543m/slvs543m.pdf

    Then we need to know the voltage and current of the heater and chiller and we can figure out how to turn them on and off. This is a very basic approach, just on/off.
    How close do you need to keep the temperature and what is making the temperature change?
     
  5. Beach

    Thread Starter New Member

    Dec 10, 2013
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    ok, here is my basic diagram.

    all will be wired to board, needs to run off normal 115 volt household power source.
    the two fans on the left will be exhaust, right will be intake. as for the thermostat/thermometer, i just need it to moniter temps and turn on/off fans at set temp and vice versa for the chiller. Temperature range will be in farenhieght and celcius depending on customer location but for now we'll
    just use F*

    65-85 +/- 3*

    so basically chiller would come on until temp reaches set temp and vice versa with fans and heater.

    im still trying to figure out the heat source. Again, i appologize for being a super noob.

    thats where the programming comes in. how to write, make it control everything, how to build the board, what chip to use..etc...

    #12 - these units will be outdoors, all over the globe. hence the need for climate control.
     
  6. Beach

    Thread Starter New Member

    Dec 10, 2013
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    also, gren rectangle is board with a chip lol. i dont know what components need to be on there, what chips to use, etc.
     
  7. MrChips

    Moderator

    Oct 2, 2009
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    Forget the programming for now. You're jumping the gun.
    What would you call this thing? What is its purpose?
     
  8. Beach

    Thread Starter New Member

    Dec 10, 2013
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    its a climate controlled enclosure. 1/4" aluminum. welded, weather tight.
     
  9. wayneh

    Expert

    Sep 9, 2010
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    You don't need programming. A thermostatically controlled chamber is not that complicated.

    What are you using for producing heat and cold? You've mentioned fans, but not a source of heat or cold. Look again at all the questions that have been asked above.

    Also, you haven't mentioned how much heat must be moved. If you're cooling something making 1W or 1gigawatt, that matters.

    I'd also be curious what sort of life you expect from this device, and how mission-critical it is. I mean, how costly is a failure?
     
  10. Beach

    Thread Starter New Member

    Dec 10, 2013
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    there will be a touchscreen monitor inside. there is a chiller unit with a fan to produce cold air, heating unit i have not figured out yet. so i just need a thermostat with multiple settings? it should hold up for quite some time. it will also be powder coated.
     
  11. MrChips

    Moderator

    Oct 2, 2009
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    What is going into the enclosure? Chickens, worms, wine, bananas, embryos?
    I imagine there is some reluctance at full disclosure but as a design engineer I could not help you without knowing.
     
  12. Beach

    Thread Starter New Member

    Dec 10, 2013
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    Indeed sir. :D

    Touch screen monitor lcd style
     
  13. dmshropshire

    Member

    Dec 1, 2013
    33
    6
    Just a little input that may help. Surveillance cameras, you may want to look into how their outdoor enclosures are built. They have heating and cooling elements that may work for you. These cameras need to operate in some of the harshest conditions. Below link is a heating element. Some also come with sensors built in.

    Just a shot in the dark, but it sounds like you are trying to achieve the same principle only in a larger scale.

    http://www.newegg.com/Product/Produ...T6311&ef_id=UlNgNwAAAF79FTpg:20131211031120:s

    Heating pads as well. Also used in camera enclosures

    http://www.alibaba.com/product-gs/529848728/110V_Small_Camera_Heating_Pad_ce.html
     
    Last edited: Dec 10, 2013
    #12 likes this.
  14. wayneh

    Expert

    Sep 9, 2010
    12,123
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    The way to really do this right is to perform an energy balance that fully considers conduction, convection and radiation from all sources including sunlight, nearby heat sources, local climate extremes and so on. If you don't want to do all that, you have to reverse engineer what others have done and hope they did their homework properly. And/or oversize the heating and cooling capacities with generous safety factors. That has a cost, but maybe trivial compared to running down all the data to any degree of accuracy.

    There have been several enclosure projects here but I'm not sure we ever had feedback on how they turned out. Hmmm...
     
  15. #12

    Expert

    Nov 30, 2010
    16,284
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    This information is so sparse that I can't tell the difference between this project and my back yard shed. It is an aluminum box, 10 feet by 14 feet, and 7 feet tall, with a window air conditioner installed in one wall. The air conditioner has an electric heating element and a thermostat accurate to 2F degrees. There is a flapper that can be adjusted to allow outdoor air to be blown into the aluminum enclosure. When I buy a new air conditioner for the shed, the odds are about 50% that it will have a touch-screen control and display.

    Seriously, do you want a work shed?
    I've been designing and installing what this box does for 40 years and I can't tell what you want.
     
  16. Beach

    Thread Starter New Member

    Dec 10, 2013
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    its not that serious #12. its enclosing a touch screen monitor. CLimate can very as long as it stays within the ranges i posted. There wont be any unstable compounds, etc...im just looking for help on controlling the units i will have in play. should i just find a thermostat with multiple settings, or will it be cheaper for me to produce these with a chip on a board. get a program written or learn how to do it. Program will just be turning things on/off based of temp readings. I told you i do appologize if im frustrating, i understand you have the knowledge and i dont..thats where we're having issues communicating. i do appreciate all of your posts though.

    thanks.
     
  17. #12

    Expert

    Nov 30, 2010
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    The enclosure will contain a touch screen monitor, right? How big? The size of a thermostat? The size of a computer monitor? Flat screen or CRT? I believe you are protecting the touch screen monitor from the external environment. Right? What are you thinking about for cooling? A Peltier junction? A Freon system? Water based evaporative cooler? What kind of power do you have available? 50Hz power grid? Batteries? Solar panel? Gasoline powered generator?
     
  18. Beach

    Thread Starter New Member

    Dec 10, 2013
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    19" on average monitor size. lcd flat panels, Peltier style cooling is my best option, and standard 115v U.S. power.
     
  19. t06afre

    AAC Fanatic!

    May 11, 2009
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    I also have problems figuring out what you want to do. So far as I understand. You will put a LCD monitor inside some enclosure. And you want to use some sort of system to take the heat generated from the LCD out of the enclosure. Is this some sort of a school project?
     
  20. Beach

    Thread Starter New Member

    Dec 10, 2013
    9
    0
    not a school project. climate needs to be controlled from heat output of lcd and outside ambient temp/cold. hence why i need to have a heater and chiller unit.
     
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