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Light intensity meter

  1. Nov 24, 2005 #1
    This is the schematic of my project (figure7)....but I don't know how to add display (ICL7107) using eagle, and how to power display .. how to connect the output voltage of stage2(second opamp) to the display?
    http://www.seas.upenn.edu/~ee205/Labs97S/Lab7/Lab7.html
    anyway , take a look at this attachment!
    best regards!
     

    Attached Files:

    Last edited: Nov 24, 2005
  2. jcsd
  3. Nov 24, 2005 #2

    mezarashi

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    That would depend on how your display works. If everything is really from 'scratch', you can implement a simple analog to digital convertor from the output. Scale it accordingly, but there's no reason to go beyond 8 to 10-bit precision. The digital output can then go into proper combinational logic so that the LEDs give you the right numbers.
     
  4. Nov 24, 2005 #3
    I've just attached eagle layout file of my circuit.
    any advices more wil be appreciated!

    best regards!
     
  5. Nov 24, 2005 #4

    mezarashi

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    This is what I meant by a simple ADC (Flash is particularly intuitive - atleast to me):

    http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/adc.html#c4

    About the LED Display and Combinational Logic, one you have a digital signal, you want to display this into something simple you can read off, you will need to input it into one of those seven-segment LED drivers (you know, the look of your calculator). How this will be really configured will depend on the bits coming from your ADC. If you use 3-bit, a total of 8 levels, you will need 1 display (0-9). If you use 4-bit or a total of 16 levels, you will need 2 displays (0-99). This link should be of some help. I can help if you need further clarification.

    http://www.play-hookey.com/digital/experiments/seven_seg_driver.html
     
  6. Nov 27, 2005 #5
    I've asked about IC7107CPL in electronic markets but they told me that it's available as ADC converter only.and i have to add display and other components that i need by myself .I shocked to hear that cause I thought that this IC contains ADC and display and many features also...
    anyway i don't know what to say more but i really need your suggestions my friends

    thanks in advance
     
  7. Nov 28, 2005 #6

    berkeman

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    Staff: Mentor

    I searched for info on the IC7107 and didn't find much. Do you have the datasheet? Also, the partial schematic that you posted doesn't seem to do much. What exactly are you trying to accomplish? What is your light sensor component exactly? A PIN photodiode, or something else?
     
  8. Nov 28, 2005 #7
  9. Nov 28, 2005 #8

    berkeman

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    Seeing your lab assignment helps -- I must have missed the original post of that. But I still don't understand where the ICL7107 display thing comes in. It looks like the display is provided in the lab as part of the lab equipment, from the way that I read the assignment. I could be wrong, but there doesn't seem to be much info on you building a display in the assignment, as opposed to just using a DVM or something in the lab as the display. Just be sure to match the output voltage range that they give you for that node.
     
  10. Nov 29, 2005 #9
    what do you mean exactly by ouput voltage range, can you help me with datasheet how to add that digital display, anyway the output voltage should be in the range 0-5 volt

    please help i don't know how to display my voltage value digitally...

    any suggestions more will be appreciated!
     
  11. Nov 29, 2005 #10

    berkeman

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    Like I said, it looked to me like you were just supposed to display the 0-5V signal on a DVM. Maybe check with your prof or a TA for clarification about the display block shown in the schematic....
     
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