Breadboard 7 segmenting without decoder plain and or chip

Discussion in 'The Projects Forum' started by theblackknight, Aug 16, 2013.

  1. theblackknight

    Thread Starter New Member

    Aug 16, 2013
    Hello guys i'm new to electronics, i'm using a breadboard and creating a 7 segment, is it possible to only use chips and or chip without decoder to create single 7 segment display 0-9?
    Also i'm confused, i have 2 switches connected directly to the common cathode of led display displaying number 1, if i press wither switch both light for example a and b disappears, i wonder why? Is my breadboard defective? If i push one switch it should switch off only one digital line but it switches off both, please help me understand what's happening. I would really appreciate the help. Big thanks in advance.
  2. MaxHeadRoom


    Jul 18, 2013
    If the display is common cathode then you do not switch this, this connected to power common and the individual segments are taken to +pwr through the appropriate resistor.
    If common anode then the reverse, this is energizing the individual LED's with a simple switch on each resistor.
  3. w2aew

    Active Member

    Jan 3, 2012
    As stated above, yes, you can certainly use them without a decoder. The 7-segment display module is really nothing more than 7 individual LEDs arranged to form the familiar squared-off 8 pattern. Many time there is an eighth LED included for a decimal point (DP).

    As the previous reply stated, these displays are available where all of the segment's LEDs have their Anodes connected together, or have all of their Cathodes connected together (Common Anode or Common Cathode). Then, all you have to do is connect up - via a current limit resistor, like any other LED - to the segments that you want to illuminate.

    If you want to be able to display every number 0-9, then you'll have to design the circuitry / switching to light up the LED segments that are needed for that digit. This is what the decoders do for you.
  4. absf

    AAC Fanatic!

    Dec 29, 2010
    The attached diagram is how I did it. You just need a handful of 1n4148 diodes. I have also designed one using TTL logic gates to teach my friend how the 7 segment decoder works. Just dont know where I kept the file. Any way I'll attach it when I find it.

    Is that what you're looking ?