Switches and You

Oz_X Mar 20, 2012

  1. Oz_X

    Oz_X First Fill-Up (of many) Founding Member

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    343
    Location:
    Rancho Cucamonga, CA
    [​IMG]
    Switches and You

    Selecting a Switch
    There are three important features to consider when selecting a switch:
    • Contacts (e.g. single pole, double throw)
    • Ratings (maximum voltage and current)
    • Method of Operation (toggle, slide, key etc.)

    Switch Contacts
    Several terms are used to describe switch contacts:
    • Pole - number of switch contact sets.
    • Throw - number of conducting positions, single or double.
    • Way - number of conducting positions, three or more.
    • Momentary - switch returns to its normal position when released.
    • Open - off position, contacts not conducting.
    • Closed - on position, contacts conducting, there may be several on positions.

    For example: the simplest on-off switch has one set of contacts (single pole) and one switching position which conducts (single throw). The switch mechanism has two positions: open (off) and closed (on), but it is called 'single throw' because only one position conducts.

    Circuit symbol for a simple on-off switch: [​IMG]

    Switch Contact Ratings
    Switch contacts are rated with a maximum voltage and current, and there may be different ratings for AC and DC. The AC values are higher because the current falls to zero many times each second and an arc is less likely to form across the switch contacts. For low voltage electronics projects the voltage rating will not matter, but you may need to check the current rating. The maximum current is less for inductive loads (coils and motors) because they cause more sparking at the contacts when switched off.


    Standard Switches
    ____________________________________________________________________________________________

    ON-OFF; Single Pole, Single Throw = SPST

    [​IMG]

    A simple on-off switch. This type can be used to switch the power supply to a circuit.
    When used with mains electricity this type of switch must be in the live wire, but it is better to use a DPST switch to isolate both live and neutral.

    [​IMG]
    SPST toggle switch

    ____________________________________________________________________________________________

    (ON)-OFF; Push-to-make = SPST Momentary

    [​IMG]

    A push-to-make switch returns to its normally open (off) position when you release the button, this is shown by the brackets around ON. This is the standard doorbell switch.

    [​IMG]
    Push-to-make switch

    ____________________________________________________________________________________________

    ON-(OFF); Push-to-break = SPST Momentary

    [​IMG]

    A push-to-break switch returns to its normally closed (on) position when you release the button.

    [​IMG]
    Push-to-break switch

    ____________________________________________________________________________________________

    ON-ON; Single Pole, Double Throw = SPDT

    [​IMG]

    This switch can be on in both positions, switching on a separate device in each case. It is often called a changeover switch. For example, a SPDT switch can be used to switch on a red lamp in one position and a green lamp in the other position. A SPDT toggle switch may be used as a simple on-off switch by connecting to COM and one of the A or B terminals shown in the diagram. A and B are interchangeable so switches are usually not labelled.

    ON-OFF-ON; SPDT Center Off
    A special version of the standard SPDT switch. It has a third switching position in the centre which is off. Momentary (ON)-OFF-(ON) versions are also available where the switch returns to the central off position when released.

    [​IMG]
    SPDT toggle switch

    [​IMG]
    SPDT slide switch (PCB mounting)

    [​IMG]
    SPDT rocker switch

    ____________________________________________________________________________________________

    Dual ON-OFF; Double Pole, Single Throw = DPST

    [​IMG]

    A pair of on-off switches which operate together (shown by the dotted line in the circuit symbol). A DPST switch is often used to switch mains electricity because it can isolate both the live and neutral connections.

    [​IMG]
    DPST rocker switch

    ____________________________________________________________________________________________

    Dual ON-ON; Double Pole, Double Throw = DPDT

    [​IMG]

    A pair of on-on switches which operate together (shown by the dotted line in the circuit symbol).

    ON-OFF-ON; DPDT Centre Off
    A special version of the standard SPDT switch. It has a third switching position in the centre which is off. This can be very useful for motor control because you have forward, off and reverse positions. Momentary (ON)-OFF-(ON) versions are also available where the switch returns to the central off position when released.

    [​IMG]
    DPDT slide switch

    ____________________________________________________________________________________________

    There are of course many other types of switches but I think these would cover most things we might need in our Xs. :salute:
     
    Last edited by a moderator: Mar 20, 2012
    Prime, NismoFire and Macland like this.
  2. NismoFire

    NismoFire Titan Swapped / SAS'd Founding Member

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    This is almost as good as porn...I love switches!!!!
     
  3. KChurch86

    KChurch86 Titan Swapped / SAS'd Founding Member

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    I can see this answering lots of questions, excellent post Oz_X!
     
  4. Macland

    Macland Titan Swapped / SAS'd Founding Member

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    Awesome! I'll be going over this in much more detail later. This is something I've struggled to understand.
     
  5. Oz_X

    Oz_X First Fill-Up (of many) Founding Member

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    Location:
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    Thanks guys! I did this a while sticky a while ago (more so I could understand it myself). I'm no electrical expert but I wanted at least to know what i was talking about when procuring elect. parts.
     
  6. Kokines

    Kokines Test Drive

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    Location:
    Ft. Hood, TX
    Good info, now I need to get some stuff for my X that requires switches....
     
  7. Ron ap Rhys

    Ron ap Rhys Bought an X Founding Member

    Messages:
    129
    Location:
    Columbus, OH
    Oz - I think the main question to answer that might help folks is what switches would we want to use for our X. For example, if you're putting in fogs and you want the switch to be illuminated with the headlights and when it lights up, what type of switch do you want? I don't believe it's any different when you're wiring up something directly or via a relay, in terms of the switch, so it wouldn't matter if it was fogs, a winch, driving lights, or anything else.
     
  8. Prime

    Prime Some Kind of In Charge? Admin

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    That's some quality switch information! Rep for sure!

    In that case you need a switch with an independent light that can be sent 12v tapped from the dash illumination and a second light that is lit when the switch is on. Usually these two lights will have separate ground pins, but they can be wired together. Alternatively they could have one pin that serves as ground for both lights.

    Take the Carling Contura SPST switches sold by ottraw.com for example. You have your power in and switch out just like any other switch but you also have an independent lower light (hot and ground) and a ground for the upper light. So 5 pins in total.
     
  9. Muadeeb

    Muadeeb Bastard Admin from Hell Admin

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    Depends on the switch. My Zombie switch is 4 pins: Switch in (also lights on lamp), switch out, upper lamp in, ground
     
  10. Prime

    Prime Some Kind of In Charge? Admin

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    Does yours have the bottom illumination for the dash light tap?
     
  11. Muadeeb

    Muadeeb Bastard Admin from Hell Admin

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    Location:
    Dallas
    It's dual illuminated
    [​IMG]

    Green on top lights up with the headlamps (ILL circuit) and the bottom bar is red when the switch is on
     
  12. Prime

    Prime Some Kind of In Charge? Admin

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    Okay, that's different. Heh. All of mine are dash illuminated on the bottom and then the top lights up when active.
     
  13. Ron ap Rhys

    Ron ap Rhys Bought an X Founding Member

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    129
    Location:
    Columbus, OH
    I've believe I've got the dual-illuminated model SPST myself. It's one of the Zombie switches. Hopefully I was smart enough to to keep the invoice so I can order the same type of switch in the future.
     
  14. Muadeeb

    Muadeeb Bastard Admin from Hell Admin

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    Location:
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    If you ordered from OTRATTW, they'll send a wiring doc, but I still recommend you grab a couple of jumpers to make sure it lights the way you think it should. I didn't and wired the top lamp backwards.

    Sent via wild ferrets on crack
     
  15. Ron ap Rhys

    Ron ap Rhys Bought an X Founding Member

    Messages:
    129
    Location:
    Columbus, OH
    I didn't end up using any jumpers. I pulled illumination from the glove box light, which goes on with the headlights and stays on even if your glove box is closed. I grounded both sides of that to a common ground and then had my normal wires in and out, along with a power line from the fusebox. I need to switch out which one I'm using as it's pulling from an always on item.
     
    Macland likes this.
  16. civicjoe

    civicjoe lone wolf mod Super Moderator Founding Member

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    aw this is the great knowledge ive been in search of!
     
  17. Ron ap Rhys

    Ron ap Rhys Bought an X Founding Member

    Messages:
    129
    Location:
    Columbus, OH
    Glad I could help? If I'd thought of it, I'd have drawn an actual diagram at the time of install, but I totally missed that one.
     
  18. leo

    leo Bought an X

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    Location:
    ny
    o men this really cool more i look xterranation more things i fine

    is everything here nice job men
     

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