Choosing an LCD display

Discussion in 'General Technical Questions and Answers' started by KP4SX, Nov 29, 2019.

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  1. KP4SX

    KP4SX Premium Subscriber QRZ Page

    I need to replace the display in my old AADE L/C meter. It does not use backlighting apparently to save on battery consumption.
    I bought a generic 16x1 display that uses the same HD44780 driver as the old one and it seems to work but...
    1. It needs to be backlit. I can cobble that together I suppose but how much current does the backlight draw?
    -or-
    2. What is the magic terminology word or color for a display that does not need backlighting so I will know what to look for?
    TIA,
    Bill
     
  2. AB5CW

    AB5CW Premium Subscriber QRZ Page

    I've had sufficient back-lighting on those LCD modules with as little as 5mA, sometimes less. LED power is typically fed via pin 15 on those LCD modules.

    In lieu of back-lighting, it's worth trying to adjust the contrast on the module. That is typically adjusted by a pot on pin 3 of the LCD module. The AADE L/C meter may have a pot in place to do that. I don't have a schematic of that product available. A 10k pot would be connected as a voltage divider. V+ to the CW terminal, Pin 3 of the LCD to the Wiper terminal and the CCW terminal of the pot connected to common/gnd.

    I'm not sure what terms to use to search for LCD modules with no back-light.
     
  3. W7UUU

    W7UUU Super Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Hi Bill - I actually have a WHOLE BOX full of the exact display that AADE used in their L/C meter - actually came from AADE after he passed away.

    Happy to send you one or two...

    Dave
    W7UUU
     
    PY2RAF and KD2ACO like this.
  4. KP4SX

    KP4SX Premium Subscriber QRZ Page

    Really? Whooda thunkit. I'd be happy to take one off your hands. Maybe two. These things are pretty old.
    I'll cover the postage cost. :)
    Thanks!
     
  5. KP4SX

    KP4SX Premium Subscriber QRZ Page

    There is a pot on the board that I haven't fiddled with since I don't know its use. I'll look into that. Thanks.
     
  6. W7UUU

    W7UUU Super Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Just to be sure - here's photos. But these I can personally attest came from AADE as part of his estate. I got them for free, brand new still in sealed bubble wrap. Our club was left all of his parts stocks when he passed away, and a small box of them ended up on the "free table" so they went home with me. The club kept a zillion of them in hopes of producing kits of the AADE L/C meter - but we haven't found the source code for the EEPROM so the project has stalled. He used two versions of this display but I have it on good authority they are interchangeable (from documentation I found)

    Check the photos - is your QRZ mailing address the one to use?

    Dave
    W7UUU


    aade4.jpg aade3.jpg aade2.jpg aade1.jpg
     
  7. AA7EJ

    AA7EJ Ham Member QRZ Page

    Word of caution - without backlight , using just the contrast pot you may have a difficulty seeing the display unless viewed directly , not in an angle.
     
  8. AA3EE

    AA3EE Ham Member QRZ Page

    Reflective needs ambient light.
    Transmissive needs a backlight.
    Transflective can go either way.
     
    AI3V, K3XR and WN6U like this.
  9. W7UUU

    W7UUU Super Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Well, in this case, Bill can either go with the OEM display of which I have many - or find an improved version.

    Pretty sure the pinout and tech is identical - AADE was not really on the "cutting edge" in the last years of its existence.

    But my offer still stands - just let me know if that's the one Bill - should be.

    Dave
    W7UUU
     
  10. W7UUU

    W7UUU Super Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    NO ONE sees your posts, Shirley. You have us all on ignore.

    Why do you bother?

    Dave
    W7UUU
     

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