Help with Brixometer design

[kaperdomo]

I have to make a brixometer/refractometer. This is a device used to measure the amount of sugar in a liquid. That's achieved by shining a ray of light through a piece of glass, and the light is refracted differently when the liquid has different levels of sugar in it.
The part I need help with is coming up with a circuit that will turn that refraction into an electrical signal and then showing it as the percentage of sugar in the liquid. So far, all I have is an LDR and an Arduino, but I realized I also need an LCD to display the number, and I'm not sure how to connect it, I would like to see if someone could help me with that. Also, if someone can come up with a better way, please let me know.

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[strawberry]

Your circuit will have low resolution. I guess sugar in a liquid wont give much change in voltage for ADC

[jbb]

An LDR might be the wrong tool for the job:
- I think a lot of them use Cadmium Sulphide (CdS) in the sensor. Cadmium is toxic and should be avoided
- you’ll only get a measurement at one point. Don’t refractometers offer a sort of bar output?

Maybe a linear photodiode array (or disassembled webcam) would be better?

[jct]

Look at the following electronic hydrometers for a more accurate solution:
https://tilthydrometer.com and even some opensource: https://github.com/universam1/iSpindel

[soldar]

I have to make a brixometer/refractometer. This is a device used to measure the amount of sugar in a liquid. That's achieved by shining a ray of light through a piece of glass, and the light is refracted differently when the liquid has different levels of sugar in it.
The part I need help with is coming up with a circuit that will turn that refraction into an electrical signal and then showing it as the percentage of sugar in the liquid. So far, all I have is an LDR and an Arduino, but I realized I also need an LCD to display the number, and I'm not sure how to connect it, I would like to see if someone could help me with that. Also, if someone can come up with a better way, please let me know.

That circuit is a total non-starter. You are way over your head here.

Brix is more commonly measured by measuring specific gravity. Note that temperature also needs to be taken into account.

What range and what precision do you need?

Degrees Brix to Specific Gravity Conversion Tables
http://www.cobell.co.uk/uploads/downloads/SG%20Tables.pdf

[CJay]

Never heard of a Brixometer before but the idea intrigued me and I immediately thought of a linear CCD array from a scanner or fax machine, turns out optical Brix meters are pretty cheap and they already exist with digital readout, using CCD arrays to measure the change in refractive index caused by a sample on a prism.

Neat application of technology and there's plenty of info about using CCD arrays with an Arduino too so from a brief read, I think the most difficult bit could be sorting out the optics.

You're almost definitely wasting your time with a CDS cell.

[cur8xgo]

I have to make a brixometer/refractometer. This is a device used to measure the amount of sugar in a liquid. That's achieved by shining a ray of light through a piece of glass, and the light is refracted differently when the liquid has different levels of sugar in it.
The part I need help with is coming up with a circuit that will turn that refraction into an electrical signal and then showing it as the percentage of sugar in the liquid. So far, all I have is an LDR and an Arduino, but I realized I also need an LCD to display the number, and I'm not sure how to connect it, I would like to see if someone could help me with that. Also, if someone can come up with a better way, please let me know.

That circuit is a total non-starter. You are way over your head here.

Brix is more commonly measured by measuring specific gravity. Note that temperature also needs to be taken into account.

What range and what precision do you need?

Degrees Brix to Specific Gravity Conversion Tables
http://www.cobell.co.uk/uploads/downloads/SG%20Tables.pdf

This.

"The part I need help with is coming up with a circuit that will turn that refraction into an electrical signal and then showing it as the percentage of sugar in the liquid. " represents the entire project, doesn't it?

Step 1, which cannot and should not be skipped, is a strategy here for how you will accomplish the project, _as project manager_ before you even get to the engineering.

[kaperdomo]

I have to make a brixometer/refractometer. This is a device used to measure the amount of sugar in a liquid. That's achieved by shining a ray of light through a piece of glass, and the light is refracted differently when the liquid has different levels of sugar in it.
The part I need help with is coming up with a circuit that will turn that refraction into an electrical signal and then showing it as the percentage of sugar in the liquid. So far, all I have is an LDR and an Arduino, but I realized I also need an LCD to display the number, and I'm not sure how to connect it, I would like to see if someone could help me with that. Also, if someone can come up with a better way, please let me know.

That circuit is a total non-starter. You are way over your head here.

Brix is more commonly measured by measuring specific gravity. Note that temperature also needs to be taken into account.

What range and what precision do you need?

Degrees Brix to Specific Gravity Conversion Tables
http://www.cobell.co.uk/uploads/downloads/SG%20Tables.pdf

I need just enough precision to measure sugar in water, not other liquids. And the range would not be that big, considering it's just for measuring that.

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[soldar]

I need just enough precision to measure sugar in water, not other liquids. And the range would not be that big, considering it's just for measuring that.

That does not answer anything and hardly makes sense. If you want to get help at least you need to communicate what you want clearly.

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What? Qué?