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spdt or dpdt switch?

Discussion in 'Pickups & Electronics [BG]' started by perutxo, Sep 10, 2008.


  1. Hi everyone,
    What's the difference between these two?
    I bought a on/on switch but it doesn't say if it's spdt or dpdt. I need the second one but ignore which one I bought.
    BTW I need it for pickup reverse phase.
    Thanks
     
  2. I forgot to mention that this switch has 9 pins (sounds like too many):confused:
     
  3. ReidK

    ReidK Jst sy n t lsy cmprsn. Supporting Member

    Briefly, SPDT means single pole, double throw. DPDT is double pole double throw. "Double throw" means that instead of "on/off", the switch is "on/on", i.e. connected to one side or the other, never disconnected. The number of poles is how many separate conductors are switched at a time. You can think of a DPDT as two SPDTs in parallel.

    Here's a good intro to switches. Starting with the picture of a knife switch makes it really clear, I think.

    Reid
     
  4. i2k

    i2k

    Oct 31, 2000
    Indonesia
    I think that's 3PDT
     
  5. ReidK

    ReidK Jst sy n t lsy cmprsn. Supporting Member

    DPDT is normally 6 pins. 9 would probably be a 3PDT, which you could use. Is yours a rotary switch (it turns like a pot knob)?

    Reid
     
  6. ReidK

    ReidK Jst sy n t lsy cmprsn. Supporting Member

    I should add that "never" isn't quite true for all switches, but we can worry about that later. :)

    Reid
     
  7. Nope, no rotary swicth, it's a lever switch. How could I use it? I've seen schematics for 6 pin but not for 9 pin,
    Thanks
     
  8. Cernael

    Cernael

    Jun 28, 2008
    You just ignore 3 of the pins, preferrably along the same edge. Then you can easily solder other stuff to them, should you later come up with something else you want the switch to do also. (Hey, it could happen!)

    To find out which pins to ignore, lay the switch on its side, so the lever goes up and down; you should ignore any one of the three vertical columns, of your choice.
     
  9. ReidK

    ReidK Jst sy n t lsy cmprsn. Supporting Member

    Just ignore three of the pins, and wire it as if it's a six pin switch. Which three? Take a look at this picture:

    [​IMG]

    Note that we're looking at the switch from the side (the lever moves side to side from this perspective). Let's call the three terminals closest to us in this picture the "first row", so there are two more rows behind it. Let's call the other dimension "columns" - the only column with all three terminals visible is the one on the left. You can use any two rows, and ignore the remaining row. If you try to do the same thing by columns, it won't work - you must have two terminalls wired in each column.

    I hope this is clear. Let me know if it isn't.

    Reid

    EDIT: Cernael posted his answer while I was editing mine. He and I are saying the same thing, we just chose different viewing angles.
     
  10. jacobmyers

    jacobmyers

    Aug 28, 2007
    Jackson, MI
    That's a friggin' lovely switch. I really like Carling's old-school designs. But the new 316PP (DPDT "stomp" switch) is nice, too, because the body is tiny (which leaves more room to work around it). Anyway...

    What you have there is a 3PDT switch. The center pins are grounds. The outer pins are the switched circuits. If you're going to "waste" this switch in a DPDT circuit, you'd ignore one row (left-center-right in the picture you posted). So you'd leave (for instance) the front three terminals alone and use the other six. But I think you already "got" that. If not, then good luck with your project.
     
  11. RyreInc

    RyreInc

    May 11, 2006
    Kalamazoo, MI
    Just some advice, I'd probably leave the middle row/column whatever unused, since the outside two are easier to work with. Electronically there is no difference tho.
     
  12. There is no ground involved unless you wire it to a ground. Don't want to confuse newbies.
     
  13. Cernael

    Cernael

    Jun 28, 2008
    Yup. The correct term is "Commons" innit?
     
  14. They aren't "commons" either. The center pole is just that - the POLE of the switch.
     
  15. jacobmyers

    jacobmyers

    Aug 28, 2007
    Jackson, MI
    I know what you mean, but the pole generally does end up (after hitting some resistance) being a path to chassis ground in an instrument (or pedal). And it is "common" in that both throws off the pole can (and usually do) share a connection to the pole.

    But yes; it is the pole of the switch.
     
  16. ReidK

    ReidK Jst sy n t lsy cmprsn. Supporting Member

    That's pretty much true of every part of the circuit, isn't it?
     
  17. morgan555@hotma

    morgan555@hotma

    Sep 16, 2008
    I gelieve this is a switch intended for a motor isn't it? Does that make any difference? As in a heavy duty switch as opposed to a light duty one? Would the resistance make a difference?
     
  18. RyreInc

    RyreInc

    May 11, 2006
    Kalamazoo, MI
    It won't make a difference, switches should have (almost) zero resistance whether they're heavy- or light-duty.
     
  19. jacobmyers

    jacobmyers

    Aug 28, 2007
    Jackson, MI
    OK, OK... That's funny. I seriously can't stop snickering. OK. Nope. Can't do it. I need to go do something else for a while.
     

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