7 Segment LED with a 6 Position Switch Help Please

Discussion in 'The Projects Forum' started by brittonracing, Mar 29, 2010.

  1. brittonracing

    Thread Starter New Member

    Mar 29, 2010
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    Hi, and thanks for you time in advance.

    In my pickup truck, I have a 6 position switch that I use to control the aftermarket "chip" for my trucks performance and towing.

    I have enough electronic knowledge to read a schematic, but not enough to make my own.

    Here is the problem. There is no way to identify what position I am in while driving down the road. I have been looking online everywhere to try to find a 7 Segment LED "driver" to work with a 6 position switch.

    I have found this schematic from a previous post, and think it would work. My question is, can I delete positions 7-12 by just unhooking all the wires attached to those positions?

    I will be working with 12VDC, and I am also not sure of the voltages needed at the parts, or the resistors needed to make the correct voltage. If someone has anything like this lying around, or any better ideas than this, please let me know.

    Any help would be greatly appreciated

    Thanks You
    Stephen
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    Hello Stephen,
    I see you found one of my old schematics.

    Yes, that circuit could be modified. Don't have time at the moment to make the changes, but I'll get 'round to doing it in a few days. If I forget (this board is quite busy) and haven't replied by the end of the week, add another reply to the end of the thread to bring it back up. If you still don't get a reply from me, send me a PM with a link to this thread.

    I typically do not like to receive PM's, but this is an exception
     
  3. brittonracing

    Thread Starter New Member

    Mar 29, 2010
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    I have downloaded Eagle Software, and made this setup, but it give me errors, and I am not sure why. I am completely new to this software, and this will be my first project like this ever. So I really would like to make it nice since it goes in my truck, and that is my baby.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    Hi again Stephen,
    I have a registered older version of Cadsoft Eagle, 4.16r2, and do not wish to pay several hundred dollars to upgrade to the new version. Unfortunately, this means that I cannot read .sch or .brd files that are created using the newer version.

    Before I even start making modifications to the existing schematic, I need to know whether the 7-segment display that you will be using is going to be common cathode, or common anode?

    In the project thread that you found from a couple of years ago, the original poster switched 7-segment displays on me several times during the thread, so it made several revisions necessary. I really do not wish to go through that again. So, before I even start making the changes, I would appreciate it if you could select the 7-segment display you wish to use, and have it in hand before I start modifying the schematic.

    Also, the 6-position switch - how is it currently wired? Do you have access to both the common terminal and the six switched terminals?

    It's important to know these kinds of things up front, otherwise revisions will be necessary down the line. It's better to know as much as possible in the beginning.

    Since you are going to be using this project in an automotive environment, a voltage regulator will be necessary to keep the supply at a constant voltage. Something like a 7808, 7809, or 7810 should work quite well.
     
  5. brittonracing

    Thread Starter New Member

    Mar 29, 2010
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    First off, for you to take the time to offer to help "basically draw the schematic" for me is AWESOME!!!! I GREATLY APPRECIATE THIS!

    I have not ordered any parts yet for this project, as I wanted to see what was going to be needed, and didn't know for sure what I could and could not do. If you are willing to draw this out with commonly available parts, I will gladly follow your advice to a T.

    I did buy a 2 pole 6 position switch from radio shack for this purpose, so that I am not interrupting the switch functions to my chip. 1 pole was going to be used for the only function of switching the chip in my truck, and the other pole was to be used for the display. I really do not want to take power away from the 1st pole for chip functions, and let the "MAGIC SMOKE" out of my $500 switch.

    I understand this is work for you, and I kind of wanted to do this on my own, but obviously it is way more complicated than I originally thought.

    If you want to draw it out, and tell me what and where to get parts-online I assume, I will do that. Or if you are willing, I will also do my own research and try to figure it out on my own, if you guide me in the direction I need to go.

    As for your questions about my project, I want to replace the single pole 6 position switch that came with my chip, with the 2 pole for reasons I mentioned above. I will be working with 11VDC to 14VDC, so if I need a regulator, I will use one.

    The only complicated part of this project, is that I want to mount the LED display in my instrument cluster, so I have a feeling I will need to run 8 wires to the LED display because the board probably will not fit in there.

    My display in my dash is green, so I was going to get a green LED display, probably around 1" tall, maybe a little smaller or bigger depending on what I can find, or you suggest. But I can not see anything smaller that a .8" display where I am going to mount it.

    I have uploaded a WORD DOCUMENT file of your drawing I modified for me. Would this be the correct way to do it, if this is what I did? Also, would it work?

    Thank you again for your time, and please let me know what you how much you would like to help me with this.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    I actually have one or two of those Radio Shack 2-pole 6-position switches around here someplace, but I can't lay my hands on one at the moment.

    Oops, just remember where I used one - OK, measured it, and determined that it is of the break-before-make type. That means the common terminal is disconnected from one switched output before the next switched output is selected.

    It would be a good idea to make certain that your kit's switch is of the same type before just hooking it up.

    Since you bought the switch from Radio Shack, does this mean you live in the USA?

    Adding your general location to your profile will be helpful to people trying to help you, as suggestions can be made for parts suppliers.

    Rather than me trying to double-check your schematic, it would make things much easier on me if you selected a 7-segment display from a vendor that has one in stock, and then order much of the necessary stuff all at once.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    Do you have the capability to make your own PCBs?

    If so, that would make the finished project much neater. The whole thing could probably fit in a small space in your dash; display, switch, regulator and driver. Having some dimensions to work with would be a help.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Take a look at this green 7-segment display that Digikey stocks:
    http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=67-1467-ND
    The display character itself is roughly 14mm tall (about 0.56")
    The display is 3/4" tall x 1/2" wide. That should be plenty easy to read.
    The face color is gray. You might want a matte black finish, I don't know.

    Here is a larger 20mm (0.80") display:
    http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=516-1235-5-ND
    The face color is also gray.
     
  9. brittonracing

    Thread Starter New Member

    Mar 29, 2010
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    I have never made my own boards, but could figure it out I think. Is this hard to do? If it can be done at home relatively inexpensive, I really would like to do it this way.

    The majority of my electronic experience comes form the 300-in-1 electronic kit from radio shack I had as a kid. I know its not much, but I understand the basics.

    I live in Ohio, so yes the USA.

    My idea with mounting and location is to actually cut a space in my instrument cluster for the display, and run like a ribbon cable or something of that sort to it to power it up. I would really like to do it this way.

    Is there a good company to order this type of stuff through? I have been looking online, and most company's are bulk order.
     
  10. brittonracing

    Thread Starter New Member

    Mar 29, 2010
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    Is DIGIKEY the place to go for this stuff? If it is, I will order from there
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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    Digikey is a hobbyist-friendy authorized distributor for a number of manufacturers' products.

    There is no minimum $ order. They will ship SMALL orders via USPS 1st Class, which can save you money. Many other vendors will only ship via Fedex or UPS, which can up the price considerably.

    There are other threads on this site detailing various processes for homemade PCB's. It's not difficult, but it helps a lot if you have things like a good laser printer and an accurate drill press.
     
  12. SgtWookie

    Expert

    Jul 17, 2007
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    As far as the face of the 7-segment display being gray, that's not really a show-stopper. You could always just use a black Sharpie pen on it to black it out; being careful to not cover up the areas where the LED light exits the display. You could also use some flat black modeler's paint (like Testor's) and a fine paintbrush.
     
  13. brittonracing

    Thread Starter New Member

    Mar 29, 2010
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    Laser printer-Check
    Accurate Drill Press-NOPE

    I will look around on DIGIKEY, and find a display and let you know the part number so you can see the specs, and we will go from there.

    Again, Thank You for the help
     
  14. brittonracing

    Thread Starter New Member

    Mar 29, 2010
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    Which display would be easier to make everything work with? Anode or Cathode
     
  15. brittonracing

    Thread Starter New Member

    Mar 29, 2010
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  16. brittonracing

    Thread Starter New Member

    Mar 29, 2010
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