Where do you usually/mostly put the switch in your simple dc circuit?

Discussion in 'General Electronics Chat' started by Lightfire, Feb 28, 2011.

when do you usually put the switch

  1. Negative

    1 vote(s)
    6.3%
  2. Positive

    15 vote(s)
    93.8%
  1. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    690
    21
    Negative
    Positive
     
  2. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    690
    21
    p.s. "which"=wrong. sorry :) it's where...

    Um, added. Why do you ussualy put the switch here (your desired answer)?
     
  3. debjit625

    Well-Known Member

    Apr 17, 2010
    790
    186
    Normally its positive,and also its standard all over the world ,I think you are asking this for only low voltage simple DC circuit for its power switching not for any other thing like switching signals in digital circuits (they are also simple DC one).
     
    Last edited: Feb 28, 2011
  4. Ctenom

    Member

    Nov 1, 2010
    59
    1
    What about double pole switches?
     
  5. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    690
    21
    I guess, double pole switches are only used in homes, buildings and infrastructures. yes, they can be used also in simple dc project but most of the projects only need 1 pole siwtch. :D *peace*

    why guys, it should be in positive. i thought it negative as the electron flows there. so if we put the switch there, on negative, it directly turn off the flows of electron.

    am i wrong???
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    It doesn't really matter, but I go for the positive side.
     
  7. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    690
    21
    since you are here bill_marsden. :)

    may i ask you?

    "Normally its positive,and also its standard all over the world" is that true???
     
  8. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    A good solid ground is always nice to have...
     
  9. debjit625

    Well-Known Member

    Apr 17, 2010
    790
    186
    If you understood "standard all over the world" is a standard by some authorities, then I am sorry because I meant in general.Electrical standards are issued by different countries by national authorities or by some well know private bodies,so they might differ.
     
  10. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    690
    21
    It seems that 'Positive' will be the winner. Others, why not choose negative? :D
     
  11. PackratKing

    Well-Known Member

    Jul 13, 2008
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    no matter which convention of electron flow you adhere to, Polarized plugs for AC being the prime example, the switch should always be placed on the "Hot" line.
     
  12. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    as many circuits have common, neutral, return, negative, etc, grounded for safety reasons, a switch at this point will not remove the potential hazard.
     
  13. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    When you have a dual powered circuit (wich often happens with opams),
    the positive AND the negative powerlines are switched.
    The "common" ground line stays unswitched.

    Bertus
     
  14. Wendy

    Moderator

    Mar 24, 2008
    20,766
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    Yes.

    The reason goes back a ways, when positive was thought to be electrons. This is known not to be the case now, but for a long time it was considered true. You cut the flow from the source.

    The reality is, it does not matter. It is tradition, and tradition is hard to break.
     
  15. magnet18

    Senior Member

    Dec 22, 2010
    1,232
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    I personally put my switches on the negative side of the circuit, assuming it's a simple DC battery powered circuit.
    I dont really have any reason, and for a simple hobby DC circuit it dosen't really matter. I just always have, I found it easier since I build everything else from the positive side, I can go ahead and put the switch on and it stays out of the way.
     
  16. debe

    Well-Known Member

    Sep 21, 2010
    946
    184
    Back in the early 70s when working on a timber fishing boat there was a problem with the batterys going flat. It turned out the OKI Radar on the boat had its power switch on the 24V negative line. When it was switched of there was considerable leakage back to the battery, through the salty wet timber in the boat, this was causing the batterys to go flat. The fix was to put a switch on the + line.
     
  17. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    690
    21
    why? why not put on negative side of the eletronics?

    electrons flow on the negative side (DC) right? so if you put the switch there, there is no more electrons flowing. am i correct?
     
  18. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
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    Electron flow stops no matter which side the switch is put on.

    There is often a lot more going on in the negative side of a DC system. The negative side of the DC system is often grounded for safety purposes. You do not really want to break that connection...

    In telephone systems the power switching is often done on the negative side. That is because they use a -48V battery to power the system. The positive side is grounded in that case. The grounded side still remains connected as it does in the case above.
     
  19. magnet18

    Senior Member

    Dec 22, 2010
    1,232
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    Could you explain how that makes any difference please??
    :confused:
     
  20. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    If the circuit has only one polarity, I will place a switch on the side furthest from whatever has been declared earth/ground/0v reference.

    Most common single-polarity (single rail) circuits use a ground reference on the negative side; the old MECL logic being a notable exception.

    As Bertus said, a dual-rail supply requires a switch in each "rail" that is away from the 0v reference.
     
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