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Technical Electrical switch question

Discussion in 'The Hokey Ass Message Board' started by Crusty Nut, Oct 26, 2015.

  1. Crusty Nut
    Joined: Aug 3, 2005
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    Crusty Nut
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  2. squirrel
    Joined: Sep 23, 2004
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    squirrel
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    Probably. Hopefully it won't burn out from too much load.
     
  3. That switch can work if wired correctly (your diagram didn't appear). I agree with Squirrel, it's a bit light-duty for a 12v motor load.
     
  4. Crusty Nut
    Joined: Aug 3, 2005
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    Well, you certainly know what you're talking about. Would you use it? Or what would you use? Just trying to avoid the super generic rectangle rocker switch that comes with the universal kits.
     

  5. It indicates 15 amp. How many amps does the motor pull, max?

    Ben
     
  6. Ask the guy if the switch has a DC rating also; most small toggle switches do. Generally, you want to de-rate AC ratings by about 1/3 or more if using them for DC. The issue on motor loads is the current inrush. While a motor is starting, current can be as much as 1200% of it's running current (but only 'instantaneously') so for good switch life the contacts should be rated for at least 150% of the running current (same thing goes for relays if you're using them). If you're using a window kit, what size fuse do they recommend? The switch should be rated as least as high as the fuse size, more is better.
     
  7. I'll note that you can also use two 2PST relays and a SPDT (with an 'off' position) switch and get around any switch limitations that way.
     
  8. squirrel
    Joined: Sep 23, 2004
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    The wiring diagram (a generic sketch of a DPDT switch wired across to reverse polarity) is on the ebay listing, it's not on this thread.
     
  9. It doesn't show up for me.....
     
  10. Davyj
    Joined: Jul 11, 2011
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  11. cretin
    Joined: Oct 10, 2006
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    The little diagram they are talking about is just a generic one for the switch. It is the second picture in the eBay ad.


    What about hiding the switch? I'm using the switches that look like window cranks on my doors, but also have hidden switches under my dash so I can easily control all windows.
     
  12. squirrel
    Joined: Sep 23, 2004
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    here's the picture, Steve. switch.jpg
     
  13. You could use a small chrome toggle switch and energise 2 relays (up and down), so you don't have to run thick wires to the big switch. Try your local radio hobby supply store. If you need a wiring diagram to use the relays, I (or someone quicker) can post it on here.
     
  14. garyf
    Joined: Aug 11, 2006
    Posts: 247

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    In most cases the power window switch just reverses the ground for up or down, no load is on the switch, so if wired correctly this switch would do the job.
     
  15. That's what I'd do, then you can use nearly any type of cutsy switches. Even antiquated 6 volt ones
     
  16. Crusty Nut
    Joined: Aug 3, 2005
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    Thanks for all the feedback. The switches that came with the kit seem pretty wimpy. I'll have to look closely for a rating on them.
     
  17. Crusty Nut
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    What is a 2pst relay? Is it a 2 post relay?
     
  18. gatz
    Joined: Jun 2, 2011
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    What squirrel posted is correct for the type of motor that has rotation reversed by swapping + - leads.

    Another type of power window motor uses the body as a ground and has 2 leads; usually color-coded.
    One lead is used for "forward", the other for "reverse".....never both at the same time !

    This is a simple diagram for an OT project I once did. The PW motor came from a GM car.
    LS1 & LS2 prevent over-extension in whatever direction the motor was going. When a Limit Switch has been reached, the motor stops turning and the SPDT switch is only effective in the opposite direction; thus moving the motor or mechanism away from that particular Limit Switch


    12v DC reversible motor circuit.JPG For circuits where a small toggle switch or hidden switch is preferred, you could wire in a relay that's rated for the load(s)

    Lots of them on eBay, Surplus Center has some 40 amp solid state relays, McMaster-Carr has quite a few, see page 949
     
  19. metlmunchr
    Joined: Jan 16, 2010
    Posts: 779

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    If you want to just use double pole double throw momentary toggle switches, then this is the type to use for 12V DC.

    http://www.colehersee.com/home/item/cat/44/55054/

    Rated 25A @ 12V DC. In general, on toggle switches that don't specify a DC rating, they're not suitable for DC use. DC current is bad to arc as the switch breaks under load. AC voltage passes thru zero volts 120 times per second for 60 cycle power, and that pass thru zero volts has a very large effect on reducing arcing as compared to DC voltage which stays constant.

    Cole Hersee switches are available from heavy truck parts houses as well as other sources. I've worked on heavy trucks, construction equipment, and earthmoving equipment off and on for 40 yrs as that was a part of the businesses my dad owned. I've never seen any brand of switches that would hold up even half as well as Cole Hersee in this sort of use. Yeah, more expensive than the Chinese ebay specials, but they also won't burn your car down when you least expect it.
     
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  20. Relays and switches are described by the number of 'poles' which is individual wires/circuits that can be switched and number of 'throws' which is switch/contact positions. So a SPST is a Single Pole Single Throw switch or relay, a 2PST is a two pole single throw, a 2P2T is a two pole, double throw. You can get relays with up to 6 poles, generally no more than 3 poles on a toggle switch. Relays will always be single throw. Relays and toggle switches will have no more than three terminals per switchable pole. Rotary switches can have more poles per each position and multiple positions, but are usually current limited.
     
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  21. Crusty Nut
    Joined: Aug 3, 2005
    Posts: 1,834

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    Thanks for the electrical hand holding. I was actually just looking at those very same cole hersee switches. Those are definitely a better quality.
     

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