Segment display question

Discussion in 'General Electronics Chat' started by peck68, Mar 22, 2010.

  1. peck68

    Thread Starter Member

    Nov 27, 2009
    Erm, i've been looking around now and i have been tempted to get a few 7 segment displays to have a play with and do some projects - however the datasheets aren't particularly that helpful...

    Can anybody explain to me how each number is made?

    Ie, is one bar lit at a time and i have to say turn on specific pins to make a shape of a number? Or is it say pin 1 turns on number 1. (just an example)

  2. retched

    AAC Fanatic!

    Dec 5, 2009
    There are IC chips that take your input and convert it to light up the propper 'bars' on the segmented displays.

    Look up the 7511. This is a 7segment display driver. There are different drivers for HEX input, DECIMAL, input or, BINARY input and can display the decimal equivalent on the LEDs

    and read this:
  3. beenthere

    Retired Moderator

    Apr 20, 2004
  4. Von

    Active Member

    Oct 29, 2008
    There are common anode and common cathode LED displays.

    There are pin(s) for the common and then a pin for each of the seven segments plus a decimal point if equiped.

    A driver IC is usually used in conjuntion with the display which actually strobes or pulses the appropriate segments to create the appearance of the number or letter desired.
  5. SgtWookie


    Jul 17, 2007
    Your application will dictate the need for either common cathode (CC) or common anode (CA) displays.

    You might be interested in looking at the 4543/4553 pair for a 3-digit counter.

    For more fun, try duplicating that functionality using a microcontroller (this is a good learning exercise for multiplexing)

    However, LED displays have been on the way out for a long time, in favor of LCD's. LCD's are much more efficient, if you do not count backlighting requirements. Each LED segment requires 10mA-20mA to drive, which is as much or more than an entire LCD display.
  6. peck68

    Thread Starter Member

    Nov 27, 2009
    Well what i want to try and do is use a 4017 as a timer, as a small project for me to do - with minutes going up to say 99. I don't really want to go into the hours as it gets a little complicated for me ;)

    I understand the 7511 IC, and the fact i can count in binary it wont be a doddle to join each leg to a corresponding bit. However, the 4543/4553 as you suggested looks a little daunting for me. :( How does it work?
    Last edited: Mar 22, 2010
  7. SgtWookie


    Jul 17, 2007
    The 4017 is not the correct IC to use for your project. Neither is the 4543/4553 pair. It would be fine if all you wanted to do is count up from 0 to 999, and then start from 0 again.

    Look for BCD counters.

    Then look for BCD to 7-segment decoders.