Electronic Product design: Fan Placement and interconnection between units

Discussion in 'General Electronics Chat' started by abhaymv, Mar 7, 2014.

  1. abhaymv

    Thread Starter Active Member

    Aug 6, 2011
    104
    4
    Hello,

    This question is related to two issues I'm facing while designing a proper product.

    I have divided the product to two modules to facilitate easy transport. They are a power supply unit (PSU) and the main unit. The first issue is related to the power supply unit and the second is related to the connection between PSU and main unit.
    Here's a brief description of my two units:


    Power supply unit: Input: 230 V AC, 2.3 A. Inside it I have three transformers and three (single layer) PCBs of similar size. The largest PCB is about the size of an A4 sheet paper. The PCBs consist of rectifiers and regulators. (And thus has many electrolytic caps). Obviously, I need an effective cooling for this power supply unit. I'm thinking of an AC fan, 230 V, 0.16 A of size 120 mm X 120 mm to cool the PSU.

    PSU shape: Cubical. I haven't worked out the exact dimensions yet, but I'm thinking of a 30 cm cube. I'm stacking PCBs inside the PSU in three layers.
    I've attached a crude paint drawing of the PSU. The green colored layers are the PCB, the fan is shown at the back side and the transformers are shown at the base.

    The ventilation are marked. In addition, there will be ventilation slits opposite to the fan. Is this arrangement good for proper outlet of heat?


    I have the following connections from PSU to main unit:
    Eight 1 A power lines.
    Four 0.5 A power lines.
    Two 5 A power lines.
    All of different rating. Also, there is a ground line capable of returning all these currents. (In case I cannot find a single ground line for the job, I may use multiple ones.)

    So, I have a lot of wires between PSU and main unit. How can I connect them without a big mess? I am currently thinking of using binding posts at each end and connect them using banana connectors, but is there a more compact way?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,507
    2,367
    Muffin fans are a usual choice, they come in 120/240vac.
    Also if the environment is unknown, it is best to provided filtered positive pressure to the enclosure.
    Filter on the outside of the fan and draw air through the filter.
    For connectors Amp/Tyco etc manuf plastic disconnect connectors similar to MS style but cheaper.
    http://www.digikey.com/classic/docu...8004/PDF/Tyco_CircularConnectors.pdf&curr=USD
    Max.
     
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  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    oh boy where to start..

    first...
    Is this a product you intend to sell or just a diy hobby thing?
    IF hobby then just use whatever..
    if professional we can't help without extensive details and I'm gonna want to be paid $ :)

    proper thermal management cannot be judged by a ms paint picture..
    inlet/exhaust opening sizing is critical.. Typically the inlet must be the same size as the outlet as far as surface area.. Then there is CFM rating/db rating/filtering/alarming,etc...

    Connectors.. there are THOUSANDS to choose from.. banana jacks/binding post would be the last type of connection I would look at..
    Those are typically used on the exterior of a "testing" device to facilitate easy attachment by lab rats.. I've never seen a professional product use them internally nor would you want to..

    There are tons of factors when choosing connectors.. shock/vibration requirements/safety standard requirements,finish/mating cycles,etc..
     
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  4. abhaymv

    Thread Starter Active Member

    Aug 6, 2011
    104
    4
    Thank you! The circular connector really appeals to me. :D

    When I checked it out in Farnell (Digi Key has no regional office in my country, I think) I saw these connectors. Do I just buy an appropriate gauge wire and connect them? Or are there cables corresponding to these connectors available?
    Its not a professional product in the sense that I do not intend to market this (at least, I have no such intention at the present time). I am an undergraduate student and this is the last stage of our project. I'm trying to make it a product... not in a marketing sense, but I guess you could say, in an engineering sense. Now its not going to be perfect, its just undergrad level, and our focus is on the electronics part. What I am looking for is a compact solution that wouldn't be an utter blunder.

    My bad... I know I should develop a better model, but I don't have enough material to work on. Do you know any book that discusses the inlet-outlet designs and such?

    Banana connectors would be my last choice too, but I'm not that familiar with the different connectors.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,507
    2,367
    Yes you have to make them up yourself, but not hard, usually a cable with a sheath of some kind is used, and the cable clamps are used as a strain relief.
    Max.
     
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  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    Circular connectors require a specific crimp tool for the terminals that get crimped onto the wire then the terminal w/wire is inserted into the plastic housing.. Be aware that the crimp tool may be pricey..
     
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