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

[DeltaX]

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 !

 

[berkeman]

Use an opamp to reverse bias the LED (using it as a photodetector) and do the photocurrent-to-voltage conversion with amplification:

http://images.google.com/imgres?img...odiode&um=1&hl=en&rlz=1T4SUNA_en___US232&sa=N

.

 

[dlgoff]

I would probably want to use a lux meter. They use photo-diodes. http://www.action-electronics.com/lightmeter.htm"

 

[DeltaX]

Use an opamp to reverse bias the LED (using it as a photodetector) and do the photocurrent-to-voltage conversion with amplification:

http://images.google.com/imgres?img...odiode&um=1&hl=en&rlz=1T4SUNA_en___US232&sa=N

.

Does the op amp need to be powered and grounded ? from the google image, I don't see that

Thanks

 

[dlgoff]

See pin 7 (+supply) and pin 4 (-supply)? It's the LF351N JFET input op-amp.