Light Intensity Meter: Schematic, ICL7107, Eagle & More

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Discussion Overview

The discussion revolves around the integration of an ICL7107 display with a light intensity meter project, specifically focusing on schematic design, component connections, and the implementation of a digital display. Participants explore various aspects of the project, including analog to digital conversion, display configuration, and component sourcing.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant shares a schematic and seeks guidance on connecting the ICL7107 display and powering it.
  • Another suggests implementing a simple analog to digital converter (ADC) from the output, recommending 8 to 10-bit precision.
  • A participant mentions the need for combinational logic to drive seven-segment LED displays based on the ADC output.
  • Concerns are raised about the availability of the ICL7107CPL, with one participant expressing surprise that it is only an ADC and does not include a display.
  • Another participant questions the purpose of the ICL7107 in the context of the lab assignment, suggesting that a digital voltmeter (DVM) may be used instead of building a display.
  • Clarification is sought regarding the output voltage range for the display and how to connect it properly.
  • Participants share links to datasheets and resources related to the ICL7107 and ADCs.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and implementation of the ICL7107 display. Some believe it should be integrated into the project, while others suggest using existing lab equipment like a DVM. The discussion remains unresolved regarding the best approach to display the voltage values digitally.

Contextual Notes

There are limitations in the information provided, including unclear assumptions about the project requirements and the specific configuration of components. The discussion also highlights a lack of consensus on whether the display is required or if alternative methods can be used.

electronic engineer
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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!
 

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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.
 
I've just attached eagle layout file of my circuit.
any advices more wil be appreciated!

best regards!
 
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
 
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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
 
electronic engineer said:
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...
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?
 
This is the datasheet for ICL7107CPL

http://www.datasheetarchive.com/semiconductors/download.php?Datasheet=931883
I use LDR as light sensitive component , it changes its resistance according to the anount of light falling on it

and my link that I've already posted and i post it again has a complete explanation about the function of my circuit

http://www.seas.upenn.edu/~ee205/Labs97S/Lab7/Lab7.html
 
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electronic engineer said:
This is the datasheet for ICL7107CPL
http://www.datasheetarchive.com/semiconductors/download.php?Datasheet=931883
I use LDR as light sensitive component , it changes its resistance according to the anount of light falling on it
and my link that I've already posted and i post it again has a complete explanation about the function of my circuit
http://www.seas.upenn.edu/~ee205/Labs97S/Lab7/Lab7.html
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.
 
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berkeman said:
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.

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!
 
  • #10
electronic engineer said:
please help i don't know how to display my voltage value digitally...
any suggestions more will be appreciated!
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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