Connect with us

Seven segment upsize

Discussion in 'General Electronics Discussion' started by robabobbob, Sep 13, 2015.

Scroll to continue with content
  1. robabobbob

    robabobbob

    2
    0
    Sep 13, 2015
    Hi, I bought a kit to build a counter circuit but the kit comes with some small seven segment displays and I wanted to use some bigger ones I have. I wasn't sure the circuit would be able to drive the larger displays assuming the draw more power but thought I'd give it a go to see however the small 7 segments displays I have are double digit with 18 pins and the large ones are single digit with 10 pins so I' missing two pins. My knowledge of electronics is limited so I'd appreciate any help someone could offer. Is what I'm trying to do possible? How can I hook up the displays with the noted pin difference.

    The kit I bought is this one: http://goo.gl/WGDltV

    Pictures attached of the led displays. 20150913_142724.jpg 20150913_142749.jpg
     
  2. eetech00

    eetech00

    95
    8
    Nov 17, 2014
    Hi

    The short answer is maybe...:D
    Do you have a schematic of the circuit and the part number of the new LED display? LED datasheet would show voltage/current requirements.

    If more current is required, might be able to add a second PCB with a ULN2003/4 to drive each new LED display.
     
    KJ6EAD likes this.
  3. AnalogKid

    AnalogKid

    2,520
    718
    Jun 10, 2015
    The future Kit website has the schematic, board layout, and pinout of the intended display. Note that the board is set up to use either common-anode or common-cathode displays with a jumper, a nice feature. If you have the pinout of your large displays, you can match the segments one-to-one.

    ak
     
    Last edited: Sep 14, 2015
  4. eetech00

    eetech00

    95
    8
    Nov 17, 2014
    After looking at the schematic..Yes. Looks like you could connect outputs of the CD4543 to the inputs of a ULN2004A. Then use the outputs of the ULN2004A to drive a 7-segment LED display.
     
  5. robabobbob

    robabobbob

    2
    0
    Sep 13, 2015
    Thanks both for the replies. That's good news it can be done but I must admit the thought of trying to add a new PCB with a ULN2004A is probably beyond my abilities.

    I don't have any schematic of the large 7 segment display but the model number is FJS23101AH. I googled it but had no joy finding info about the pin outs. I will contact the seller on ebay to see if they can provide them.
     
  6. AnalogKid

    AnalogKid

    2,520
    718
    Jun 10, 2015
    If you know the intended operating voltage and current of the large display segments, you can map the pinout with a power supply or battery and a resistor. Large displays often have multiple LEDs in series for each segment, so while the operating current probably is a fairly standard 10 to 20 mA, the minimum voltage to get light might be 10 V.

    ak
     
  7. Colin Mitchell

    Colin Mitchell

    1,416
    313
    Aug 31, 2014
    The minimum voltage to get light is 8v so you need 10v to 12v supply and a 100R dropper resistor.
    The chip will not be able to deliver the full 20mA per segment, but you will get some illumination.
    A=7 B=6 C=4 D=3 E=2 F=9 G=9 DP=8
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-