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How to interpret datasheets? (akak 7-segment displays)

  1. Feb 17, 2012 #1
  2. jcsd
  3. Feb 18, 2012 #2

    vk6kro

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    Science Advisor

    This display needs multiplexing.

    You need to select which digit you want and then apply a positive voltage to that anode connection at the top of the diagram. You have a choice of three.

    Then you need to select which segments of the chosen digit are to be lit. This will depend on the number you want to display.
    So, you might turn on ABCDEFG to get the number 8 and you do this by grounding these pins on the display via a current limiting resistor and the output of an IC.

    This is done rapidly so that the eye thinks all the digits are on at the same time.

    So, the display gets +5 volts on an anode from a multiplexing Integrated circuit, current flows from that anode, through a LED, through a limiting resistor, maybe 100 ohms, and then into the IC again and thence to the negative supply line.
    There are 3 digit counter chips that provide multiplexing like this in their outputs.

    Here is a voltmeter circuit that uses a similar display. Note that it uses transistors to give more current to the display.
    circuit.GIF
     
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