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7 specific volatges to to 1,n,2,3,4,5,6 numbers in Alpha-numeric Display

Discussion in 'Hobby Electronics' started by [email protected], Feb 5, 2006.

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  1. Guest

    What I am attempting is to take 7 specific voltages, and display
    certain numbers for these specific voltages on an alpha-numeric

    What I currently have is a resistor ladder that breaks up the voltage.
    The resistors form a ladder that breaks up the 5v from a voltage
    regulator into reference signals to determine at what voltages an
    LM339N will use to ground each corresponding LED. It use 1% resistors
    to make sure I get exact reference voltages because in the higher gears
    the signal is very close and there is not much gap between voltages.
    The output voltages from the sensor are as follows
    1st gear = 1.782v
    2nd gear = 2.242v
    3rd gear = 2.960v
    4th gear = 3.630v
    5th gear = 4.310v
    6th gear = 4.660v
    Neutral = 5.000v
    The comparators in this circuit will turn on each LED as follows:
    1st LED = Anything over 1.022v
    2nd LED = Anything over 2.043v
    3rd LED = Anything over 2.660v
    4th LED = Anything over 3.356v
    5th LED = Anything over 4.052v
    6th LED = Anything over 4.526v

    I now want to take thes voltages and convert them to show the proper
    gear on an alpha-numeric display.

    How can I turn what I have working in to alpha numeric?

    Or, Do I have to start a whole new circuit. Something that takes the
    voltage and turns it into a digital signal and then sends to an A/N LED
  2. Franc Zabkar

    Franc Zabkar Guest

    Use the comparator outputs to drive a 74LS148 8-line-to-3-line
    priority encoder (or something similar), and then follow this with a
    BCD-to-7 segment decoder/driver. I'd use an additional comparator to
    detect neutral, and then apply this signal to the enable input of the
    74148 so that the display is blanked.

    - Franc Zabkar
  3. Poxy

    Poxy Guest

    How about using a LM3914 in dot mode with each output driving the required
    pins of the LED display via diodes?
  4. Guest

    Anyone with a good idea feel free to post schematic, as it will help me
    make sense of all this.
  5. Guest

    yes it is for a motorbike, GSXR actually.

    Love that line about the program with soldering iron. I have no fear
    in programming with a computer, I actually do this for a
    living(computers) but not electronics.

    I just need to know what chips to use for my soldering iron Basc
    And seven segment is enough as an "n" can be made.
  6. Phil Allison

    Phil Allison Guest


    ** LED displays are rendered in invisible in average daylight.

    ........ Phil
  7. Ken Taylor

    Ken Taylor Guest

    Since you have digital outputs from your comparators, if you don't want to
    send them to a PIC and do some code-crunching, send these to an EPROM as the
    address lines and use the outputs to drive the seven-segment display.
    Program the EPROM to suit.


  8. Franc Zabkar

    Franc Zabkar Guest

    You could probably do everything with a single PICAXE-18X chip:

    The PICAXE has a built-in ADC and an on-chip BASIC interpreter. No
    comparators would be needed, only the LED digit, and driver
    transistors for each segment. The chip can be programmed via a PC
    serial port.

    - Franc Zabkar
  9. Poxy

    Poxy Guest

  10. LOL, yeah, tell that to the traffic light designers and message board
    manufacturers. I suppose the auto manufacturers are wrong too, as are
    the manufacturers of truck indicator and stop lights.
  11. Phil Allison

    Phil Allison Guest

    "The Real Andy"

    = Andrew Pearson:

    Andy is a despicable, chronic alcoholic, anencephalic, autistic moron from

    Then there are his bad points.


    Anyone can try a typical 7 segment LED display in bright daylight and see
    the outcome.

    ......... Phil
  12. Quote from Phil
    "** LED displays are rendered in invisible in average
  13. Phil Allison

    Phil Allison Guest

    "The Real Andy"

    ** Run out of little kiddies to molest have you - Andy ??

    Or just getting over another MONSTER hangover ???

    Or is it both ??


    Andrew Pearson:

    We all know you are just another autistic *FUCKWIT* electrician from
    Brisbane with a FUCKED attitude to everything.

    ........ Phil
  14. YAWN......
  15. Guest

    Would a PIC16LF84A-04I/P or a PIC16F873A-I/SP accomplish this as I can
    get samples of these only so far.
  16. The 16F873 has an internal ADC so yes it is suitable. The 16LF84 does
    not have an ADC so you can't easily use it.
    Depending on the precision required you may need an external voltage
    reference for the ADC.

    A PICAXE would be much better if you have not used a microcontroller
    before, much easier to program.

    Dave :)
  17. Guest

    Anyone know what the code would look like for the 873A?.

    I should be able to wire the output voltage from the sensor to the PIC,
    and the outputs with resistors to the diplay, but what does the code
    look like internally?
  18. Guest

  19. Poxy

    Poxy Guest

    Yes, they are selling a kit with a pre-programmed PIC. Obviously if you want
    to use your own PIC you'll have to write the code yourself. There are many
    approaches to coding PICs - I'd suggest you do a Google search on PIC

    As someone else suggested, you should consider using a PICAXE chip as they
    are much easier to code and get started with.
  20. Guest

    Going to order the PICAXE, but do I need the 18, 18X or the 18A.

    Also can I feed it the voltage right from the sensor output?

    Or do I have to do something special to it so it can read acurrately
    and do the approriate action.

    Who ever said that the PICAXE is easy to learn is right. Fairly basic
    programming and compiler that come with it are good to.
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