Newbie..learning..help?

Discussion in 'The Projects Forum' started by james211, May 29, 2012.

  1. james211

    Thread Starter Member

    May 29, 2012
    210
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    Hello,

    First off, I'm happy to have found this forum and I look forward to hopefully getting some help with a small project.

    A few months ago I started a saltwater aquarium and needless to say its keeping me busy. Anyways, one of the things I need help with is building a programmable fan cooler. I have the code and the circuit diagram, but to be honest I've never read a circuit diagram so I have no clue where to start.

    I have done a lot of soldering and building my own basic electronics with radioshack circuit boards and project boxes but nothing like this, and even this seems pretty simple.

    I'm not sure where to start other than gathering the pieces listed on the diagram. Any insights would be great. I've attached the diagram for you to see.

    If I'm out of line and you don't think this is doable for a newbie please let me know.

    Best,
    James.
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
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    Most of it looks OK, but what's a DS18820? I can't find any data on it.

    Ken
     
  3. james211

    Thread Starter Member

    May 29, 2012
    210
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    Its actually a DS18B20, a waterproof temp sensor. The gist of it is, I have never read circuit schematics before, so I should probably start by learning how to read those then maybe I wouldn't have any problems figuring this thing out.
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    Have you used a PICAXE before?
     
  5. james211

    Thread Starter Member

    May 29, 2012
    210
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    I have not, is it tough to work with? I've done some basic programming before and their website seems to make things simple to understand. Any insights?
     
  6. MrChips

    Moderator

    Oct 2, 2009
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    Well then you'd better get started doing simple things first, like making an LED flash.
     
  7. james211

    Thread Starter Member

    May 29, 2012
    210
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    The entire program for the picaxe has been written so I just need to load that into the controller. The entire project is on a DIY site for reefbuilders. I figure I'll take one step at a time and hit this site up with questions.
     
  8. absf

    Senior Member

    Dec 29, 2010
    1,493
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    The reason to use a mcu is to make the project programmable.

    I dont see any preset or variable resistor in the circuit that if you want the fan to run on a lower or higher temperature, How are you going to change it if you dont know how to modify the source code? :confused:

    Allen
     
    Last edited: May 30, 2012
  9. james211

    Thread Starter Member

    May 29, 2012
    210
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    Here is a link the whole project. The terms are you talking about are a bit over my head unfortunately. What I think you're saying is that a variable resistor would allow for the fans to run at higher or lower rpm's is that correct?

    http://ozreef.org/content/view/297/29/
     
  10. BSomer

    Member

    Dec 28, 2011
    433
    106
    What absf is referring to is changing the temperature at which the fan comes on or shuts off. Now that you have provided the link to the original project I see that the temperature set points for the fan are in the program code along with the fan speed controls. If the fan speed or the temperature settings are not giving you the desired effect you have to change those in the program itself and test it again.
     
  11. james211

    Thread Starter Member

    May 29, 2012
    210
    2
    Based on this diagram, here is a list of what I think I need, there are a few questions in there as well, those are in bold. Any assistance is appreciated.

    1 x Power Supply - 12v / 1.5amp
    1 x SPST Switch
    1 x Diode (not sure what the rating on this diode is ???)
    1 x 100uf Capacitor (any additional specs I need to know about?)
    1 x LM7805 (Looks like most are 5v, but what amp rating?)
    1 x 10uf Capacitor (any additional specs I need to know about?)
    1 x DS18B20 Temp Sensor
    1 x 4.7k ohm resistor
    1 x 22k ohm resistor
    1 x 10k ohm resistor
    1 x 330R resistor
    ***Anything I should know when buying resistors, I noticed a lot of options***
    1 x LED
    1 x BUZ71 MOSFET ( ANY SPECS?)
    The "Download" on the diagram, I assume that's the socket for programming the IC?

    I know this is a lot and I appreciate anyone who takes the time to go through this list. I'm sure if I had studied some basic electronics I could figure all this out.

    Many thanks!

    Lastly..whats your favorite all-in-one source for buying parts?
     
  12. BSomer

    Member

    Dec 28, 2011
    433
    106
    I think that any 1N400X series will work fine for this. Such as the 1N4004

    This is one of the filter capacitors for the regulator. You need to consider what the input voltage will be and to be safe go approximately double that for the voltage rating of the capoacitor.

    The LM78XX series regulators are a 1.5 Amp regulator. If you are going to be getting close to that or are using a supply voltage considerably higher than 5 VDC you should put a heatsink on the regulator.

    You can use a 10 or 16 volt capacitor for this. It is basically the same story for the other capacitor.

    If you plan on doing a lot of electronics in the future, buy in bulk and buy according to the E12 / E24 standards. One of the more common sizes is the 1/4 watt 5% resistors. Read through this link to understand more about the E-series stuff... http://www.logwell.com/tech/components/resistor_values.html

    It is a 17A 50V N-channel MOSFET. Read the datasheet for more info.
    http://www.datasheetcatalog.com/datasheets_pdf/B/U/Z/7/BUZ71.shtml

    That looks correct to me.

    I like to use Jameco and Mouser for the most part. There are others that I use on occasion like Electronic Goldmine (has some odd stuff from time to time) or Newark.

    I hope this helps out some.. :)
     
  13. wayneh

    Expert

    Sep 9, 2010
    12,150
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    I heartily agree with the recommendation to buy in bulk. The shipping charge for your entire list will likely be more than the parts themselves. For any item less than 10¢ or so, I often just order 3 or 4 for every one I actually need. And for resistors, it's incredibly handy to have an entire set, maybe a couple hundred spanning a wide range, say from 1Ω to 10MΩ. It'll only cost a few dollars and can last you for years of experiments and DIY builds. DigiKey is another one to add to the BSomer's list. Lately I've been using Mouser the most - I like their search and filtering tools.
     
  14. MrChips

    Moderator

    Oct 2, 2009
    12,449
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    All resistors have a power rating. Make sure the resistor is rated at minimum twice the power generated in circuit. Usually 0.25W is a standard wattage to select.

    All resistors have a tolerance rating. For most circuits, 5% tolerance is ok.
    Some folks prefer to stock 1% since they are not that more expensive.

    All capacitors have a voltage rating.
    For capacitors under 1μF, 50V rating is common and will work for most circuits. Make sure the rating is at minimum twice the voltage in circuit.

    All electrolytic capacitors have a voltage rating. Pay close attention in this case because the physical size and cost goes up with the voltage rating. Don't go much higher than is necessary. For a 5v circuit, 10v to 16v rating is fine. Avoid using too low rating since electrolytics tend to short and the results can be disastrous when they fail.

    The tolerance of capacitance is not so important except in sensitive timing or filter applications. 20% tolerance on electrolytics is common. 5% for others.
     
  15. BSomer

    Member

    Dec 28, 2011
    433
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    One thing I forgot to mention about the capacitors is that most electrolytic capacitors are polarity sensitive. Pay close attention to this or you may end up with flying debris. :eek:

    Electrolytic capacitors have a mark on them indicating which side is the ground, or more negative. This mark varies between the manufacturers, but is usually a colored stripe with a "0" or a "-" in the stripe.
     
  16. james211

    Thread Starter Member

    May 29, 2012
    210
    2
    Thank you guys sooo much!!! :)

    Its nice when people on these forums don't make you feel like an idiot when your just beginning.

    Thank you again, I'm sure I'll be back with many more questions!
     
  17. MrChips

    Moderator

    Oct 2, 2009
    12,449
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    BTW, capacitors over 1μF tend to be electrolytics in order to keep the size down.
    Hence your 10μF and 100μF caps will both be electrolytics.

    Your choice is between tantalum or aluminum.
    For your application, aluminum is OK and will likely be less expensive.
     
  18. wayneh

    Expert

    Sep 9, 2010
    12,150
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    An IRF540N is a cheap, common and easy to find MOSFET if you need an alternative to the other. I believe Radio Shack stocks the lower-current-rated IRF510 in stores, if you're in a hurry.

    BTW, one thing missing from your list is the fans themselves. Maybe you already have them?
     
    Last edited: May 30, 2012
  19. james211

    Thread Starter Member

    May 29, 2012
    210
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    I do already have them. I have two 120mm / 3000rpm cooler master fans.
     
  20. james211

    Thread Starter Member

    May 29, 2012
    210
    2
    How does this look? Also, I know a lot of these only come in bulk, but do you think I could buy any of them at Radioshack or some where in NYC? I only ask because I don't know where I will ever use several hundred resistors. The price is right, but I hate wasting.
     
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