An electronic hydrometer I'm working on

[chris2012]

Hi guys,

I've been working on making an electronic hydrometer ( http://www.openhydrometer.com/about )
to graph your specific gravity, it's a work-in-progress
at the moment, i'm hopefully going to have a soldered prototype tommorow

At the moment I've got a breadboard with a single sensor connected, but I'm going to add
a number of them to a hydrometer tommorow and see how it goes.

Any critique on the page or the hardware would be great!

cheers

Chris

[gnutz2]

A great idea , especially as you could map your fermentation live on a computer.

[orlando]

This is a great idea Chris and I really hope you pull it off. Traditional hydrometers are too open to interpretation and if you like to take multiple measurements of the progress of the brew you push your sanitation rigour to the limit. Can I assume that the device will be able to cope with at least sanitation ior even sterilisation before it goes into the brew without having its function impaired? My other question concerns getting the data into the PC/Laptop etc. I ferment in a fridge to maintain the fermentation temperatures that I want. This obviously presents something of a challenge, what do you have in mind to make this possible?

[Dr. Dextrin]

My concern would be that in an actively fermenting brew you will get bubbles forming on the hydrometer, causing an incorrect reading. Also, there will be bubbles of gas and currents in the liquid itself, another possible source of error. Both of these could be quite hard to calibrate out.

[kane]

interesting concept!

Would it make more sense to mount the magnets on the hydrometer and have the hall sensors mounted on the float?
That way the hydrometer could be spun like it usually would to remove some of the gas bubbles that would interfere with the reading (as well as not having wires which could possibly add to the weight if not positioned correctly?)
They could also be sealed and easier to clean for example if the hydrometer gets covered in krausen.

Looking forward to hear how it turns out!

Kane

[Jocky]

My concern would be that in an actively fermenting brew you will get bubbles forming on the hydrometer, causing an incorrect reading. Also, there will be bubbles of gas and currents in the liquid itself, another possible source of error. Both of these could be quite hard to calibrate out.

This was my immediate thought too. Still, it's worth trying to see if it can be done.

[chris2012]

"Can I assume that the device will be able to cope with at least sanitation ior even sterilisation before it goes into the brew" - that's a good point orlando, i'm thinking of encasing the hydrometer & sensors in some kind of plastic bag/balloon.

" I ferment in a fridge to maintain the fermentation temperatures that I want." - I'll have a think about that one, potentially you could use wifi on the RaspberryPi, however this would mean you'd probably have to power it from batteries? within the fridge.

"My concern would be that in an actively fermenting brew you will get bubbles forming on the hydrometer, causing an incorrect reading." - This is a good point, i'm hoping the magnetic fields (i'm using strong rare earth magnets) would still be able to reach the sensors though.

"Would it make more sense to mount the magnets on the hydrometer and have the hall sensors mounted on the float?" - this wouldn't be possible unfourtunately, as the hall effect sensor wouldn't know which particular magnet it was seeing.

Cheers guys for the feedback!

[Underground Joe]

You will also get deposits stuck on the hydrometer that will give a false reading. I thought in the past about a low tech version of this, ie just chucking a hydrometer in each brew but I never did it because I didn't think it would be anywhere near accurate.

[chris2012]

Can you explain how the deposits would give false readings in this case?
Provided the magnetic fields still reach the sensor, it should still work.

[Dr. Dextrin]

"My concern would be that in an actively fermenting brew you will get bubbles forming on the hydrometer, causing an incorrect reading." - This is a good point, i'm hoping the magnetic fields (i'm using strong rare earth magnets) would still be able to reach the sensors though.

It's not the sensors, it's the fact that the bubbles buoy the hydrometer up.

[chris2012]

Oh sorry, misunderstood that.

[setmash]

Check this out, its kickstarter funded and hit its goal. This could be a very nice piece of kit :

http://thebeerbug.com/?submit.x=149&sub ... ormat=html

[Hogarth]

Good luck with this. For me, it'd be too much gubbins floating around in my beer. But gadget heads are bound to want one.

On your web page you claim that a 2nd-hand refractometer costs £150, but I think you can buy new ones on ebay for about £20, and people seem to be happy with them.

[chris2012]

That's for ones you can leave in-situ in the beer. Those ones for £20 are ones you put a sample of beer on.

[Hogarth]

That's for ones you can leave in-situ in the beer. Those ones for £20 are ones you put a sample of beer on.

Oops. Apologies.