Can the LF351N op-amp accurately measure light intensity in a fish tank?

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Discussion Overview

The discussion revolves around the feasibility of using the LF351N op-amp to measure light intensity in a fish tank, specifically through a plexiglass setup. Participants explore various methods for achieving accurate voltage measurements in relation to changes in liquid levels, including the use of photodetectors and op-amps.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests using Light Dependent Detectors and Photo Diodes after finding photodetector transistors inaccurate.
  • Another participant proposes using an op-amp to reverse bias an LED as a photodetector and perform photocurrent-to-voltage conversion with amplification.
  • A different viewpoint mentions the use of a lux meter, which typically employs photo-diodes for measuring light intensity.
  • There is a repeated suggestion regarding the use of an op-amp for photocurrent-to-voltage conversion, with a query about the necessity of powering and grounding the op-amp.
  • A later reply clarifies that the LF351N op-amp has specific power supply pin configurations (pin 7 for positive supply and pin 4 for negative supply).

Areas of Agreement / Disagreement

Participants express differing opinions on the best approach to measure light intensity, with no consensus on the most effective method. Some advocate for using photodetectors and op-amps, while others suggest lux meters.

Contextual Notes

The discussion includes assumptions about the operational characteristics of the LF351N op-amp and the configurations necessary for its use, which remain unresolved.

Who May Find This Useful

Individuals interested in electronics, specifically in applications related to light measurement and sensor design, may find this discussion relevant.

DeltaX
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Hello everybody,

I am trying to measure the light intensity of light going through a plexiglass (U Shaped) in a fish tank using led. I would love to see accurate voltage measurements due to the change in the liquid level. I tried photodetecr transistors; it wasn't accurate at all. I am thinking about using Light Dependent Detectors and Photo Diodes. Any suggestions ?Thanks !
 
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See pin 7 (+supply) and pin 4 (-supply)? It's the LF351N JFET input op-amp.
 

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