Double 7 segment led help

Discussion in 'The Projects Forum' started by corsasri, Jul 20, 2010.

  1. corsasri

    Thread Starter New Member

    Jul 20, 2010
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    0
    Hello all hope you will be able to help me. I need to build a Double 7 segment led to read the number 95 thats all a static display. But not sure what i will need and how to make it work.
    I know i will need a double led i will use this type: http://www.maplin.co.uk/Module.aspx?ModuleNo=2166
    the Common Cathode type

    i dont know what conections on that unit will display 95 (but think you will)
    the unit will be powerd by a 9 volt battery or maybe 2aa batterys (what is best ?)
    it will have an on and off switch. This is simple i can do
    Now to resitors i know i need them so not to blow my led up .If i can use one single resistor that would be best and maybe have many wires coming from that to the lcd display. But I need to know what size and type resistor to buy. thats if it can be done.

    i would like to wire everything directly to the led display i dont want to make a circit board.

    so if you can help that will be great. if you need any extra info i will do my best to help you.

    thanksgary
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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  3. corsasri

    Thread Starter New Member

    Jul 20, 2010
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    do i conect the + of the battery to the led bord then the resistors form a point on the bord. and the battery to -
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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  5. corsasri

    Thread Starter New Member

    Jul 20, 2010
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    still a bit confused. i can get the led segments to light up but not sure where to go next.
    here is a little diagram.
    0= PIN 1
    9= PIN 9
    R= PIN 10
    X= PIN 18
    D- des point on front of display


    0 I I I I I I I 9



    D D

    R I I I I I I I X


    pin 5 i think is earth or ground.
    how do i do the resistors do i, from + wire of the battery add a resistor to pin 0, then a resistor from pin 0 to say pin 11 then another resistor from pin 11 back to pin 5 earth making the circuit complete.

    hope this makes sence
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
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    The common cathode goes to the battery negative terminal. The positive voltage is applied through individual resistors to the LED segments, also individually.

    To make a 9 means lighting segments a, b, c, & f. A 5 uses a, f, g, c, & d. Look at the data sheet.
     
  7. corsasri

    Thread Starter New Member

    Jul 20, 2010
    5
    0
    thanks for all the help. i now have a double counter that that is reading 95.
    but have done it like this the from the + battery to a pin then i have conected all the pins i needed with a strand of wire. then found an - that makes them all lite up. did use a resistor but the led lights up real dim. removed the resistor and conected to the led now nice and bight. the led is now using no resistors, but dose feel a bit warm, has been displaying 95 now for over an hour with no resistors without any problems apart from dose feel a tad warm.
    do you recomend using a smaller resistor ?
     
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