Connect with us

Help Selecting A Switch (Novice)

Discussion in 'General Electronics Discussion' started by NewKindOfClown, Jan 23, 2015.

Scroll to continue with content
  1. NewKindOfClown

    NewKindOfClown

    7
    1
    Jan 23, 2015
    Hey, all. I'm a complete novice in the field of electronics, and I'm hoping you can help me figure something out.

    I have two separate LED strips that will receive power from the same 12V source. I want to install a switch so I can route power to whichever lights I want lit. What I'd like to have is a three position switch: one for the green lights, one for blacklights, and one that will illuminate both strips together.

    Would someone be willing to tell me exactly what I'm looking for in a switch? If you could point me toward one, and possibly even give me tips on wiring, I'd greatly appreciate it.

    The extent of my electronics knowledge is wiring speakers, so please feel free to explain things as if I were a child. I won't be offended.

    Edit:
    I'm not picky about the method of selection. It could be a toggle, a rotary, a pull knob, or anything else that'll accomplish the task. Oh, and it'll be in a Jeep, so weatherproof would be a big plus.
     
    Last edited: Jan 23, 2015
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    Hi there and welcome to Electronics Point :)

    A rotary switch is probably your best option - they're easy to mount, and they're available with various numbers of positions. They're not the cheapest switches available though.

    Slide switches are available but they are harder to mount in a panel, and ones with three or four positions don't fit with your control requirements.

    Speaking of control requirements, don't you want an OFF position as well?

    Also, do you know how much current your LED panels draw? This is important because switches are rated for a certain switching current and can be damaged over time if the current is exceeded.

    Switches are described by the number of positions, and the number of poles. Each pole is a separate switching circuit. In your application, it would be easiest to use one pole for each LED strip, so a double pole switch would be best. It is possible to use a single-pole switch and diodes though, so a double pole switch isn't essential.

    The switch you want is a bit specialised, so you won't find anything suitable at Radio Shack, for example. The widest range of components is available from Digi-Key and Mouser. I'm looking at Digi-Key but once you know what you're looking for, you can try http://www.mouser.com as well. Their freight charges can be high so check before you order.

    Here is Digi-Key's best option: http://www.digikey.com/product-detail/en/C5P0206N-A/451-1028-ND/514082
    USD 10.63, double-pole, sealed, 1A DC rating, with a configurable number of positions from 2 to 6, so you can add an OFF position if you want. It has a "flatted" shaft ("D"-shaped section) to take a suitable knob.

    It's only rated for 1A though. If either one of your panels draws more than that, the switch will be running beyond its specifications and its life will be shortened.

    There are other more complicated options for controlling the panels. See what you think of that one.
     
    chopnhack likes this.
  3. NewKindOfClown

    NewKindOfClown

    7
    1
    Jan 23, 2015
    Thank you for the greeting, and thank you far more for taking the time to help.
    Price isn't too much of an issue, as this will be a one-off project. I haven't installed any components yet, either, so I can work around size issues even if the switch has a large footprint.

    The light controller will handle On/Off and the flashing functions. I'm simply looking for a switch to route power to the proper light(s).
    From the LED manufacturer site: "Power Consumption: 24W (about 2 amps) per 16.4 foot roll"
    I'll be running 2ft of each color, so 4ft of LEDs with full illumination. If it's a linear function, that should be 6W max at 12V DC, which would be a .5A load if my math is correct.
    I wasn't sure if a relay would be needed here, but it seems to me the 1A switch would work for the .5A max load (again, if my understanding is correct). Could you help me with wiring that rotary switch? A position for green and a position for blacklight is simple, but what would I do to wire the third position that lights both strips?

    I can't stress enough how narrow my understanding of this field is, but here is the basic idea I came up with earlier. I'm open to criticism.
    DPST center open switch:
    Strip 1 to position 1
    Strip 2 to position 3
    Leads to both strips to position 2
    Use diodes to prevent power from flowing through position 2 when position 1 or 3 is selected
     
    hevans1944 likes this.
  4. hevans1944

    hevans1944 Hop - AC8NS

    4,630
    2,159
    Jun 21, 2012
    What you are asking for can be achieved with a special double-pole triple-throw (DP3T) miniature toggle switch, Model
    M2044B2B3W01-VA from NKK switches, available from Digi-Key here. Other manufacturers also make this specialty three-position toggle switch. The contact switching arrangement is unique to allow each pole to be selectively connected to one (and only one) of three contacts for each position of the switch: left, center, and right. This is shown in the switch diagrams as ON-ON-ON. An external jumper wire is required for each pole to obtain the desired triple-throw operation.

    When wiring this switch, each string of LEDs is wired to one of two separate poles of the switch. The +12 V DC supply is then wired to the three positions provided for each pole as desired. For example, if the green LED strip is ON when the toggle switch is in the left position, the blacklight LED strip is ON when the switch is in the right position, and both LED strips are ON when the toggle switch is in the center position, you would designate one pole of the toggle switch for the green LED strip and the other pole for the blacklight LED strip and then follow the switch wiring diagram to connect +12 V DC to the switch contacts on the first pole that are closed when the switch is in the left and center positions. Then also connect +12 V DC to the switch contacts on the other pole that are closed when the switch is in the right and center positions.

    This may sound confusing, but the +12 V DC connections are simply "daisy chained" among four contact positions on the switch. I have attached a PDF page from the NKK website. The wiring diagram is located in the lower right corner of the page. Note one pole of the switch is on the left side of the diagram and the other pole is on the right. The two terminals labeled "common" are where you connect the two LED strips. The terminals labeled "out" are where you connect the +12 V DC. Refer to the switch diagrams above the connection diagram to see which "out" is connected to "common" for each of the three toggle switch positions.

    Be sure to read @KrisBlueNZ description of switches and their current limitations above. The switch I selected for you has a rather modest current rating of only 3A DC. You can use two relays with 12 V DC coils and SPST contacts with higher current ratings in place of the LED strips. If you do that, the toggle switch will operate the relays which will then switch current to the two LED strips.

    73 de AC8NS
    Hop
     

    Attached Files:

  5. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    I suspect Hop's idea is better but here's what I had in mind using the Digi-Key part I linked in post #2.

    272383.001.GIF

    The two wires on the right go to the positive sides of the LED strips and the negative sides of the LED strips are returned to chassis.
     
  6. NewKindOfClown

    NewKindOfClown

    7
    1
    Jan 23, 2015
    I was about to throw in the towel and ask for someone to spoon feed me, but I think I got it. Using the .pdf file that hevans1944 was kind enough to link, here is the logic path that I see:
    Switch Function.png

    If I followed that correctly, I give full credit to you gentlemen. Is that right?

    Edit: I found another page on the site. The LEDs are 70mA per foot. I'm using 4ft when all lights are illuminated. That comes to .28A total.
     
    Last edited: Jan 23, 2015
  7. NewKindOfClown

    NewKindOfClown

    7
    1
    Jan 23, 2015
    I seem to have lost my Edit button, so I suppose I'll bump my post. I think I understand the operation of the switch (and circuit) as outlined directly above, but I don't see that particular toggle switch listed in stock anywhere. After looking at Mouser and doing some searching, I've come to a list of toggle switches, here.

    They all seem basically the same, aside from size. Would it be correct to assume that the terminals would be the same as the one listed, since they all begin with part number M2044 from NKK?

    Is there a reason why any/all of these wouldn't work for my application?

    Thank you again, both of you. I greatly appreciate your assistance.
     
  8. hevans1944

    hevans1944 Hop - AC8NS

    4,630
    2,159
    Jun 21, 2012
    Near as I can tell, any M2044 series switch from NKK should work. Differences in part numbers appear to be related to terminal type and switch body mounting styles.

    Use Kris' wiring diagram. That is, 12 V applied to two positions at each pole. Can't tell if you did that with the NKK toggle (my vision is poor) but you should have four 12 V connections to the toggle switch.
     
  9. Arouse1973

    Arouse1973 Adam

    5,164
    1,087
    Dec 18, 2013
    I had to Hop, 73 de AC8NS is your call sign?
    Adam
     
  10. hevans1944

    hevans1944 Hop - AC8NS

    4,630
    2,159
    Jun 21, 2012
    Adam, AC8NS is my call sign. Look me up on QRZ.com. 73 translates to "best wishes" and de is French for "from".
     
    Arouse1973 likes this.
  11. NewKindOfClown

    NewKindOfClown

    7
    1
    Jan 23, 2015
    I ended up placing an order for NKK p/n M2044SS1W01. It should arrive sometime next week, and I'll be sure to post an update once I have everything set up. Thank you again for your assistance.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-