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Digital Voltmeter!! on Breadboard

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by remon7, May 23, 2014.

  1. 4pyros

    4pyros Well-Known Member Most Helpful Member

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    The 7660 makes the -5 volts that goes to pin 26 of the ICL7107
     
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  2. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Pin #26 is fed by the 7660 charge pump, hence -5V from the +5 supply. Easy to check with a DVM.


    ==

    If the LED display is really suspect, then one needs to compare the datasheet for the one that's needed and try to light the display segments with the series resistor and power supply. What I asked to do as a test.

    Alternatively, you can disconnect all of the segments. Leave the ANODES connected. Now connect each segment to ground through a resistor (The same one I said to test with) and each LED should light the same segment of the LED. Compare with the datasheet.
     
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  3. remon7

    remon7 Active Member

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    Today i will start work again .................
     
  4. dave

    Dave New Member

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  5. 4pyros

    4pyros Well-Known Member Most Helpful Member

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    good luck
     
  6. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The display is supposed to be common anode. It is simple to test if it is common cathode or common anode.
    The IC has a test pin #37. When it is at a logic high (it sinks 15mA!) then the display should read 1888.

    Most of the schematics posted show the 10uF capacitor at the output of the ICM7660 voltage polarity converter connected with backwards polarity.
     
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  7. remon7

    remon7 Active Member

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    I did not get u ...what about 37 pin with Power supply !!!!! volts ??? only 37 ,,necessary about negative and positive ....
     
  8. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    It does say 7106 but it may apply to the 7107

    The second function is a “lamp test”. When TEST is pulled
    high (to V+) all segments will be turned on and the display
    should read “1888”. The TEST pin will sink about 15mA
    under these conditions.

    CAUTION: In the lamp test mode, the segments have a constant DC
    voltage (no square-wave). This may burn the LCD display if main-
    tained for extended periods.
     
  9. audioguru

    audioguru Well-Known Member Most Helpful Member

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    I guess you do not have Intersil's datasheet or their 8 applications notes about it.
     
  10. remon7

    remon7 Active Member

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    i did not get you..... in silly things i was failed ...
     
  11. 4pyros

    4pyros Well-Known Member Most Helpful Member

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    Is it working?
    Did you check the negative supply?
    Did you try the test pin to test the display?
     
  12. remon7

    remon7 Active Member

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    No... :'( ...I have to collect right 7 segment display same as figure(Circuit diagram).................... MAN6910 maybe.
     

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