Standard LED Display Components

Discussion in 'General Electronics Chat' started by Wendy, Mar 9, 2009.

  1. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    I'm planning ahead for some counter experiments using 7 segment displays. The shear number of display types is extremely large, unlike CMOS logic types. I bought some MAN74A, small common cathode LED displays, but it occured to me they might not be the most common kind out there (though I have seen them for over 30 years kicking around). What kinds of display components are available in your area? I'd like to get something that is available everywhere.
     
  2. mik3

    Senior Member

    Feb 4, 2008
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    Check what large supplier companies like Digikey, Farnel etc sell. I think everyone can order from them easily.
     
  3. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    That's not the point, these are local. How about Austrailia, or the UK, or Asia? I have a huge selection of parts on hand, I can make pretty much anything I want from my POP (pile of parts).

    For the newer folks, I have been writing for the AAC book experiments. Basically I want the most common (hopefully least expensive) stuff out there.

    Part of what got me to thinking was I saw some TI311 display units (they have a built in decoder), but they are completely obsolete and aren't really available anymore. I don't want to get something else that someone can't get.
     
  4. gotumal

    Active Member

    Mar 24, 2008
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    LT543 type displays with common cathod or anode pin and a to g, dp pins have been getting used since ages in Asia. I believe they are the most common 7- seg displays.
     
  5. Wendy

    Thread Starter Moderator

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    The LT543 keeps coming up a 5mm conventional LED doing a database search. Could you refine that a little please?
     
  6. Wendy

    Thread Starter Moderator

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    OK, so I go to the old standbye, Radio Shack. Their P/N 276-0075 looks awfully familiar. I buy one as a reference, and it comes up MAN74 on the reciept. Go figure. Guess MAN74 is the part, it's small (IC sized) and protoboard friendly. BTW, MAN74 can be bought for a lot less elsewhere.

    [​IMG]
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    Bill,
    Here's a Fairchild datasheet that contains the MAN74A:
    http://www.ee.washington.edu/stores/DataSheets/optoelec/7segled.pdf
    It's common cathode.
    Common anode displays can be easier to deal with, as driver IC's such as 74x47's and ULN2003/ULN2803 are only capable of sinking current. CMOS 4511, 4543 drivers can source current for the common cathode displays, so those aren't a total loss ;) It just depends on what your application is.
     
  8. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    My application is another experiment for the AAC book, I need a common part to use for counter circuitry. I plan on using a CD4511 decoder, which will drive a common cathode with only a resistor. Back in the day it would have been a 7447/7448.

    The next question (for the counter) is do I use J/K S/R flip flops (two per package) or a 4 bit counter? I lean to the former, a CD4027, since that is a basic building block, but the latter is more useful over time. Something like a CD4020/4024/4040, which is a ripple counter, a 4518 (a dual BCD counter), or a CD4029 Binary/BCD Presetable Up/Down Counter (my favorite).

    My intent is to show some clock circuits, mod 6, mod 10, mod 12, and mod 24 counters. Digital clocks seem to be one of our big hitters.

    After that I plan on introducing multiplexing, if there is room on a protoboard.
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    It would probably be most helpful to those interested if you demonstrated using various IC's.

    The 4543/4553 combination makes for a pretty simple 3-digit up-counter display, with built-in multiplexing. I even have an example circuit if you'd like to fiddle with it.
    FYI; U1 is a UDN3130 Hall-effect sensor. The idea was to keep track of turns on a coil winder. A $1 pedometer from the dollar store turned out to be more expeditious, less expensive, and have two more digits. ;)
     
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