7 Segment LED display

Discussion in 'The Projects Forum' started by noltex, Jul 24, 2007.

  1. noltex

    Thread Starter Member

    Apr 18, 2006
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    I need a circuit that will allow me to display digits 0-9 on a 7 segment LED that it switched by a 10 position rotary switch. Each position on the rotary switch corresponds to a digit. Is there a simple way to do this?
     
  2. lightingman

    Senior Member

    Apr 19, 2007
    374
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    Hi...The simple wat to do it is with diodes..... I will post a schematic later this evening.....Daniel.
     
  3. techroomt

    Senior Member

    May 19, 2004
    198
    1
    a 10 line to 4 line encoder (74147 or equiv) and a bcd to 7 seg/decoder/driver (7447a or equiv) should do the trick. these can be had in ttl or cmos families.
     
  4. noltex

    Thread Starter Member

    Apr 18, 2006
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    Thanks. My skills are basic enough that I need a schematic. Theory won't do it for me.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    I suggest you go with techroomt's recommendation.

    You certainly could do it by using 49 diodes and seven current limiting resistors - but you would need to make a lot of connections.
     
  6. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
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    I suggest a decimal to BCD encoder connected to a BCD to 7-segment driver by the means of an inverter. Use this scheme:
    Decimal to BCD encoder -> Inverter -> BCD to 7-segment driver

    Decimal to BCD encoders:
    74LS147 (TTL);
    74HC147 (CMOS);
    74HCT147 (CMOS/TTL compatible).

    Inverters:
    74LS04 (TTL);
    4069 (CMOS);
    74HC04 (CMOS);
    74HCT04 (CMOS/TTL compatible).

    BCD to 7-segment drivers:
    74LS47 (TTL);
    4511 (CMOS);
    74HC4511 (CMOS);
    74HCT4511 (CMOS/TTL compatible).
     
  7. noltex

    Thread Starter Member

    Apr 18, 2006
    15
    0
    Any helpful schematics for those ideas? I'm a bit limited when it comes to theory.
     
  8. lightingman

    Senior Member

    Apr 19, 2007
    374
    22
    That's why I sugested diodes....I was going to mention the use of a 74HC147 into a CD4511....O.K. I will post both schematics tomorrow, as I have been just a bit busy today...Daniel.
     
  9. noltex

    Thread Starter Member

    Apr 18, 2006
    15
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    Thanks, I appreciate any help I can get.

    Jeff
     
  10. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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  11. noltex

    Thread Starter Member

    Apr 18, 2006
    15
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    I can't seem to connect to that address for some reason.
     
  12. lightingman

    Senior Member

    Apr 19, 2007
    374
    22
    Hi,I am so sorry that I have not yet posted the schematics for you....I have had one hell of a day and am still working now at 21:53, and will still be at it until midnight.... I will post them tomorrow, as I have more or less a free day....You will be best of using CMOS, as it is less fussy about supply voltage, and is very low power.....Daniel.
     
  13. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
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    The CMOS equivalent might be better, since consumes less power and drives better.
     
  14. lightingman

    Senior Member

    Apr 19, 2007
    374
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    O.K....Now I have just had time to sit and think about this one..... It is not going to work with just the priority encoder, as the zero will only be displayed when all the switches are off... I.E. each time a button is released, the display will return to zero.....This means that a latch arangenent would have to be added to hold the last number sellected, this would make it a lot more complicated.....It would mean the addition of a 10 input OR arangement to trigger a one-shot, and using the latch input on the CD4511 to hold the last digit sellected.....Do you wan't to go that far ????Daniel.
     
  15. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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  16. noltex

    Thread Starter Member

    Apr 18, 2006
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    As I said in my original post, I'd like to be able to use a 10 position rotary switch to have a 7 segment led display digits 0-9. I don't know enough about the various options for any of them to make sense on how to do it. I'm just looking for a schematic.

    Thanks for any help you can give me with this.

    Jeff
     
  17. dionaide

    New Member

    Jul 30, 2007
    7
    0
    How Can I Make This 3-digit Display?
     
  18. noltex

    Thread Starter Member

    Apr 18, 2006
    15
    0
    That looks like it may work for what I need. Anyone have a schematic I can use? I just need to be able to turn a 10 position rotary switch to make a 7 segment LED display #'s 0-9.

    Thanks for your help.
     
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