traffic light controlled by 4 position switch

Discussion in 'The Projects Forum' started by tmdteach, Oct 3, 2012.

  1. tmdteach

    Thread Starter New Member

    Oct 3, 2012
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    My 10 year old son wants to be a working traffic light for Halloween. He loves learning about circuits. I want to wire a very simple circuit using a 4 position switch so he can control the state of the light: Off, green only, yellow only, red only. I was thinking of using 3 battery operated LED Christmas string lights as the light sources. I am a novice but am willing to tackle this with some guidance.

    So...
    1) Can I use a 4 position switch for what I think I can (to create those 4 states)?
    2) Can I strip the battery connector off the string lights, connect to the 4 position switch and then reconnect the switch to a battery compartment?
    3) Do you recommend a different light source or wiring arrangement (the simpler the better)

    This is a homemade costume that he is in charge of with wiring help from me (from you:) ). He's thought of using transparent colored plexiglass (or maybe transparent colored plastic plates) for the lenses, a painted cardboard box, cardboard or foam for the lens visor. Comments or help is tremendously appreciated.
     
  2. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
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    Welcome to AAC!

    This is fairly straight-forward. I assume you are talking about white LED Christmas lights that are battery-powered? If so, you can remove the battery packs from the lights and wire them as shown in the attached image. Be sure to pay attention to which wire goes to the + and - of the battery packs - orientation is critical.

    Take a look at the image and let us know if you have any questions.

    I'm not sure where you are located, but if in the U.S., you can purchased colored plastic from here: http://www.tapplastics.com/product/...plastic/acrylic_sheets_transparent_colors/519

    I suggest the dark red, dark green, and dark yellow.
     
  3. tmdteach

    Thread Starter New Member

    Oct 3, 2012
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    Thanks so much! That is exactly what I was hoping would work. I am wondering if I should use white LEDs or get strings in red, yellow and green. I assume the white ones will be brighter behind lens/diffuser. Do you happen to know where I could purchase tinted, transparent diffusers or what I could use in place of a plexiglass/diffuser combo? I'm concerned that the string lights will be too muted behind two layers when the string is just running off some AA batteries.
     
    Last edited: Oct 3, 2012
  4. elec_mech

    Senior Member

    Nov 12, 2008
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    This is for a Halloween costume, correct? You don't want the lights too bright, otherwise observers will feel like they are looking into a flashlight. There is a balance and the answer lies in how you want the traffic light to look.

    The AAs won't affect brightness, they'll only determine how long the lights will remain lit for.

    Options:

    #1 The simplest would be to use colored LEDs without worrying about a diffuser or any cover. They will be plenty bright but not too bright.

    #2 The next option would be to use colored LEDs with color, transparent acrylic. The output will not be affected much and it will add a little more clarity.

    #3 Same as above but with white LEDs. The look of the color will be better with colored LEDs, but depending on the intensity of the white LEDs, these may come across as brighter.

    #4 You can use translucent (not transparent) plastic with very bright white LEDs.

    #5 This just occurred to me. You could also go with colored LEDs and cover them with clear, textured plastic to help diffuse the light without losing much brightness. I'd suggest the plastic used for ceiling lights which can be found in the U.S. in Home Depot.

    This all boils down to what you can get your hands on for the battery-pack LED lights, the look you're going for, and how much time and effort you want to put into it.

    Transparent plastic: http://www.tapplastics.com/product/...plastic/acrylic_sheets_transparent_colors/519
     
  5. tmdteach

    Thread Starter New Member

    Oct 3, 2012
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    #5 This just occurred to me. You could also go with colored LEDs and cover them with clear, textured plastic to help diffuse the light without losing much brightness. I'd suggest the plastic used for ceiling lights which can be found in the U.S. in Home Depot.

    That's what I was thinking to use as a diffuser behind a colored acrylic lens. I was hoping, though, to find a plastic diffuser like this that is itself tinted red, green, yellow. I just can't seem to find that product so perhaps it's not produced. Maybe easiest to just use a clear diffuser as the lens with colored lights.
     
  6. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,802
    832
    Some links for you - just to help give you some ideas.

    Colored Cellophane

    Clear light panels from Home Depot

    The first one could be used with clear LED lights - the second with colored LEDs.

    Also, consider searching for Stained Glass Paints; this may give you additional options, for example, using clear LEDs and painting them with the desired color. This source is but one.

    Just a few ideas to consider...
     
  7. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
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    Well, I've tried looking for textured, colored plastic with little success for an exact match. However, it may be easier to just buy it premade:

    http://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l2736&_nkw=plastic+traffic+light+lenses+

    Some other things I found:

    Translucent plastic: http://www.archplastics.com/us_california_plastic_distributor/lumasite_001.html#light

    Colored Plastic Bags which could be used to diffuse white LEDs:
    http://www.papermart.com/Product Pages/Product.aspx?GroupID=18979

    Textured, Colored Plastic: http://www.solterplastics.com/plastics/textured/
     
  8. williamj

    Active Member

    Sep 3, 2009
    180
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    with colored lights you might want to try bubble wrap for a diffused transparent lens.

    williamj
     
  9. tmdteach

    Thread Starter New Member

    Oct 3, 2012
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    I called a company that sells traffic light lens to see if they had any old ones to buy cheap. Generously, they sent me lenses to borrow!

    I've tried several different sets of battery powered LED string lights (10 to 36 lights) under a lens and they just not bright enough. One set that has 24 lights is almost usable. My question is, can I connect two sets of lights to the same poles on the 4 position switch so that both get turned on. Each light set uses 4 AA batteries. Do I need to use a battery pack that houses more voltage if I connect two string lights to the same position?
     
  10. elec_mech

    Senior Member

    Nov 12, 2008
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    The simplest thing to do is connect the two sets in parallel. Each set of lights will have a positive lead and a negative lead. Connect both positive leads together and connect both negative leads together. This will wear the batteries down faster, but for an evening of trick or treating, you should be fine.

    Only if you opt to connect the two sets in series: positive lead from set #1 connected to negative lead of set #2, then negative lead from set #1 and positive lead from set #2 go to switch/battery pack. In this case, you need double the number of batteries in series - instead of 6VDC (4 x AA), you'll need 12VDC (8 x AA). I suggest sticking with a parallel connection for ease of use.

    I played with another idea last week while on vacation. I took some large balloons and wrapped them around a 4" or so craft hoop made for cross-stitch. I then bought some battery-powered push-on lights made for closets and put them behind the stretched balloons. The lights did a decent job - the red was a little dim because the balloon was more opaque than translucent, but it looked fine in the dark. My goal was to find something to do this quick, easy, and cheap. I got the balloons and lights from the Dollar Tree and the hoops from a craft store. Altogether, about $7. I'll try to post pictures soon. Meant to do this sooner, but I've been busy and wasn't sure if you were still working on this.

    I played with LED X-mas lights, but found they were too dim as well. If you stick with the lenses you have, I suggest using some cheap LED flashlights or the closet light I mentioned earlier. I liked the closet light because it has three LEDs spaced an inch or so apart, so it's like having a wide flashlight. Alternately, you could wrap a few cheap flashlights together behind each lense. It'll be a little more challenging wiring these to a switch and battery pack, but it can be done. You can remove the back end of the flashlight (which houses the batteries) to save space.
     
  11. tmdteach

    Thread Starter New Member

    Oct 3, 2012
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    Very cool. Clever idea with the stretched balloons. My son loves the look of the actually lenses so I think I shot myself in the foot by borrowing them :)

    Called several electrical supply stores in my area and can't seem to find the type of switch I'm looking for. Is there a specific name other than calling it a 4 position switch. What is being recommended is 3 single switches then he'll have to turn a color off before turning the next one on. I'd prefer it does that through the wiring itself. I'm thinking a rotary switch should work. I'm not familiar with the jargon of these switches. How many "poles" and "ways" do I need for what I want to do. Maybe if I specifically ask for that at a store, I'll find it easier???
     
  12. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
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    Hmm, what you are looking for is referred to as a SP4T (single pole, 4 throw) switch. Unfortunately, these are not common items. If you go to an electronics parts store, ask them for a rotary switch with 4 or more positions. It can be double pole - this is may be more common and won't affect the operation. You may be able to find something at a musical instrument store called a 4-way rotary pickup selector switch such as this: http://www.guitarelectronics.com/product/SWR41/4-Way-Rotary-Guitar-Pickup-Selector-Switch.html. I'm not 100% this is the ticket, but I'm pretty sure it can be made to work.

    I can look for a vendor to order from online if you'd like.

    Alternately, you could use three switches - one to turn the circuit on and off, and two to control which lights come on. This isn't as nice as having a single switch, but your child can use two switches and only have one light come on at a time.

    I threw together a simple circuit showing a couple of options.
     
  13. tmdteach

    Thread Starter New Member

    Oct 3, 2012
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    0
    Only took 5 hours of online searching and calling, but found the switch linked below and it seems perfect. Good thing I'm as excited about this project as my son! They believe they were originally made for toaster ovens. Should come in by end of week. Was told it should still work with a DC source as it just provides the contacts. Any opinion on that?

    Don't know if picture will show, so here's a link to it:

    https://docs.google.com/open?id=0B-fnlgDBDqKyc044YzlvbmF5REk

    [​IMG]
     
  14. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    Ah, that would be perfect!

    I've attached pictures showing the balloon idea I mentioned as well as how to wire lights to your new switch. Note that it is important the polarity (+ & - leads) are hooked up correctly.
     
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