LED Displays, Hard To find Data sheets

Discussion in 'Electronics Resources' started by kbyrne, Sep 17, 2016.

  1. kbyrne

    Thread Starter Member

    Dec 10, 2011
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    I have a couple of projects in mind that call for Common Cathode LED displays. In my stock is 21 pieces I bought in a grab bag type buy to experiment with and here lies the problems:
    1. Common Anode
    2. Data Sheet search only shows up MAN59234 Common Anode No Decimal points. I have two versions and both have two decimal points each.
    3. Number 1 sample Top row 727 space F, Bottom row MAN59234
    Number 2 sample Top row Space 640, Bottom row MAN59234 space F
    Question what is the difference as they both have 7 legs on the side of lettering and 8 legs on the other side, and the data sheet states no decimal point but both have two decimal points. The data sheet also shows 8 legs on the side of lettering
    but my part has 7. I have the part number right but it might be discontinued so how can I use these up in a circuit by a change from Common Cathode to Common Anode with out specs as I am new to electronics. I have Data sheet for anyone to view if need be.
     
  2. AlbertHall

    Well-Known Member

    Jun 4, 2014
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  3. kbyrne

    Thread Starter Member

    Dec 10, 2011
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    Good deal for checking as I have less legs than I should have per other pin charts.
     
  4. dl324

    Distinguished Member

    Mar 30, 2015
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    For CA displays, the segment drivers will sink current; you'll need to modify the circuit to source current. The digit drivers will source current and you'll need to modify the circuit to sink.

    Post the datasheet and the circuit using CC displays for more specific suggestions.
     
  5. kbyrne

    Thread Starter Member

    Dec 10, 2011
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    This is the only Data Sheet I could find for MAN59234 but note my parts have two decimal points, this data sheet is for a part no decimal point at all. How do I determine which leg is which. That is my first question as well as how can I find the right data sheet.
     
  6. takao21203

    Distinguished Member

    Apr 28, 2012
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    just apply the pins with DMM until you get a segment lighting up and then cycle through
     
  7. dl324

    Distinguished Member

    Mar 30, 2015
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    It has been mentioned twice to use the diode check function on a DMM; I use a continuity checker that consists of 2 AAA batteries and a flashlight bulb.

    Put the negative (or positive) lead on a pin and touch the other lead to all of the other pins, one at a time. When a segment lights, one end will be the common terminal. If nothing lights, swap the leads on that pin and do it again. Once you've found the common pin, you can map out all of the segments.
    If the display has no markings, finding a datasheet will be impossible. You'll be able to find datasheets for parts with the same pinout, but an exact match is unlikely.

    Post a picture of the display, front and back, and the schematic of the circuit you want to use them in.

    How do you know they're the wrong polarity?
     
  8. kbyrne

    Thread Starter Member

    Dec 10, 2011
    84
    2
    With all of your help I have figured out my displays that are common anodes. Pin 4 to V+ (9vdc) thru resistor 330ohm. The pins one at a time to gnd. My volt meter must be at fault as that did not work. This project calls for a LCD Display I believe but I want to use my MAN 7 Segments. What is the difference between the two if any?
     
  9. dl324

    Distinguished Member

    Mar 30, 2015
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    Post a schematic.
    Try google.

    LCDs block or reflect light. LEDs generate light.
     
  10. kbyrne

    Thread Starter Member

    Dec 10, 2011
    84
    2
    Got that info plus Driver info so after all my circuit is led type marked with display. This picture is actually my question. How to change from Common Anode to Common Cathode or vice versa. But due to google and
    a reply all it really amounts to is resistor or transistor to pins the right way. Now I have all the info I need
    to study. Sorry for my stupid questions. Common Anode Circuit Example uploaded Best wishes to all.
     
  11. dl324

    Distinguished Member

    Mar 30, 2015
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    Any decent CD4511 datasheet will have examples:

    Common cathode:
    upload_2016-9-18_9-42-55.png

    Common anode:
    upload_2016-9-18_9-43-11.png
    In this example, the base resistor needs to provide 10X the segment current. The collector resistor needs to limit segment current to a safe value. Any general purpose NPN transistor can be used.

    LCD:
    upload_2016-9-18_9-43-25.png
     
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  12. kbyrne

    Thread Starter Member

    Dec 10, 2011
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    Tanks Dennis that opens up a different way for me to view my problem also. I have figured out my questions today on breadboard and google searches also. That LCD display will bee looked into next for future info. Best regards Kevin
     
  13. takao21203

    Distinguished Member

    Apr 28, 2012
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    you cant change LCD to LED. LCD needs AC waveform, and some kinds are non multiplexed. Others are.
     
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  14. kbyrne

    Thread Starter Member

    Dec 10, 2011
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    I will continue to look at LCD's due to interest in them. But thank you for info. Why do manufactures produce a
    MAN59234 7 segment with decimal points (2) and no pin to light them up?
     
  15. dl324

    Distinguished Member

    Mar 30, 2015
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    Because there was demand for a display with no decimal points and they chose to use an existing package that had optics for one.

    I have some 2 digit displays and the most significant digit is only capable of displaying '1'. They also have light pipes for decimal points that are non-functional.
     
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  16. ian field

    Distinguished Member

    Oct 27, 2012
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    Display units are highly standardised - if you identify the general characteristics of the part you have; the datasheet from the nearest big name manufacturer will give you most of what you need.

    There are a few colour choices, loads of digit sizes and where the DP is if there are any. A few manufacturers do oddball pin layouts - but they're a minority.

    Not sure whether they're still made - but there were digit units with built in counter, latch and decoder-driver. At one time; there were plenty of onboard ROM starburst displays that could do the complete ASCII set.
     
  17. kbyrne

    Thread Starter Member

    Dec 10, 2011
    84
    2
    Tanks again for all the input to ponder. I guess a resistor and led will have to do for this Volt And Amp meter project.
    and Temp project also for dp. Kevin
     
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