how to convert voltage to brix?

I need a program to convert photodetector output (voltage) to brix value

op560a.pdf

i have attached the data sheet of the PD and IR LED.

IRL 81A, Lead (Pb) Free Product - RoHS Compliant.pdf

Hi,

brix? do you mean the sugar content of a fluid?

I just read at wikipeda about it. They speak of the IR absorption. I can′t help you with doing FFT at IR frequency spectrum.

Afaik. you can also use the angle of total reflection to calculate brix. Just put the fluid on a glass with known optical density. from below adjust a laser beam to point to the area where the fluid is on the glass.
Adjust the angle (laser beam to glass) to find the point of total reflection. The angle is in relation with brix. Maybe you find a table with the relationship.

Klaus

i have to use fiber optic to detect the refractive index of the sugar :)

A versatile method for taking output from a sensor. It resembles a wheatstone bridge.

The op amp amplifies the difference between your signal and the reference voltage.

You will need to experiment with resistor values, to find what creates usable volt readings.

thanks for the prompt reply mate. is there anyway to control the pot value in microcontroller because every time i need to adjust the pot to increase the IR Sensor intensity

As an alternate to adjusting the resistance but keep the voltage constant, you can also change the voltage through an unchanging resistance. The microcontroller can create a voltage by means of D-to-A conversion, or whatever method is least trouble.

i need a circuit for this http://www.osram-os.com/Graphics/XPi...0Compliant.pdf IR LED


must be low power consumption?


can i use 3.3v 110ma battery 37ohm resistor to fire the led or it need any other components required like 555timer?

i need one more help what is the minimum volt and ampere that this LED work?

LED current and pulsed versus DC operation will be commanded by your application. Nobody can answer the question without knowing your optical design.

We can guess that modulated light (=pulsed LED) may be preferable because it's a way to get rid of ambient light interferences.