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Lcd or led display tachometer. How can i build one?

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by swiftakias, Mar 5, 2004.

  1. csaba911

    csaba911 Member

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    Yes it is working fine. :wink:
    Exept after "99" =9900 rpm, turn in to 0c instead of "00".
    I gues if you runing ower 9900 rpm you are nuts or runing in first gear at 100km/h. :?:


    STEVE
     
  2. kirlcheah

    kirlcheah New Member

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    can anyone tell me how to make this circuit work in proteus? i have drawn everything on lite and then make the pic on the hex file. what more i have to do to make it run like they have in the examples?
     
  3. surfr

    surfr New Member

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    Steve, after 99 (9900 rpm) which is the maximum count, it is suppose to display O/r (over-range). :wink:
    So, you did not have any problems with the display multiplexing.
    Hm, I bought some new led digits and I will try once more.

    Thanks for the feedback.
     
  4. dave

    Dave New Member

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  5. csaba911

    csaba911 Member

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    You right about the Or that what I mean, newer thought is stand for Over range.
    and no, I had no problem using your hex file, just uploaded to mi PIC and up&running, no need to change anything.
    On the link I posted earlier you can find a easy input circuit.


    STEVE :arrow:
     
  6. scholesy

    scholesy New Member

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    Someone might be able to do something whizzy to create an LED-analogue hybrid. Maybe a semi-circle of small green 1.8mm LEDs at 200rpm intervals, with orange 1.8mm LEDs at the 1000's of revs. Red for the red-line of course.

    You might be able to use a LM3914 or LM3915 (not sure if rev count is linear or log?). One of these packages should cover a 2000rpm range, so four would be enough. Of course, you need a few LEDs :)

    I'm a near-novice, so have no idea how you would start drawing a circuit for this..... if anyone does have one; please let me know!

    kind regards
     
  7. surfr

    surfr New Member

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    For displaying you have to cascade four LM3914's. But you will also need a frequency to voltage converter circuit for the input. Try looking around the net for that, there are particular ic's that can do that.

    If you ask me, it is not worth to get into so much trouble (too many ic's on the pcb) for just a tachometer!
     
  8. GynZi

    GynZi New Member

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    I think you could do this with a single PIC... I have no experience programming pics, but i do know how they work... You could make it light a led between every 1000rpm, and maybe blink at 500rpm... so if your engine was running at 3500rpm, 3 leds would be lit and one would blink... same way all the way to 11000rpm... one pin on the PIC would be used for switching between 1, 2, 4, 6 and 8 cylinder engine, one for measuring the spark interval... i'd use the only pic i have experience with, PIC16F84... (yeah, can't program others :()
     
  9. surfr

    surfr New Member

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    usfhugs88

    Hope this helps!

    Manos
     

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  10. marianol

    marianol New Member

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    Re: usfhugs88

    Do you happen to have the schematic of the Analog/Digital tach? or at least where and how to conect the leds for the bar-graph display.

    Thanks,
    MarianoL :D
     
  11. surfr

    surfr New Member

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    Re: usfhugs88

    I am no longer working on this project, but it is not too dificult to find that out reading the code. From what I remember, I think the code needs some corrections regarding the bargraph display. If I find any time I will try to do it, but right now it is not possible. Try reading the code and decode the porta and portb definitions. Then correct the bargraph table.
     
  12. eduponto

    eduponto New Member

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    upload article

    can upload original EPE article..........or other with lcd or led........

    Thanks in advance
     
  13. chemelec

    chemelec Well-Known Member

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    Digital Tachometers look PRETTY, But Unfortunately by the time it reads your Actual RPM, You have Probably BLOWN UP YOUR MOTOR.
    Particularly True if used in a Racing Situation where you need to Rev up a lot.

    Analogue is Far Superior, Except for Possible Vibration problems that mainly occur in High Speed Boats.

    Gary
     
  14. finch661

    finch661 New Member

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    how can the 7 seg output be changed for a bank of LEDs?
     

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