Roasted
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Found this thread when searching Google - have just broken another glass hydrometer - would be interested in digital readout or USB link for SG and Temperature
I think expensive part is the physical technology to make the measurement. The digital portion should be straightforward and inexpensive. I have yet to find a simple sensor for this and I have been looking for a very long time.
This is how I understand the measurement: Imagine a weight is attached to a bar at the end and a bar is fixed on a wall. When you hit the weight by a finger, the weight starts vibrating. Now you will find that the heavier the weight becomes, the slower it vibrates and vice versa. This is because the weight will vibrate on the oscillation period specific to a substance in proportion to the mass of a weight. This means that one can determine the density of a substance by measuring its oscillation period since density becomes proportional to the mass when the volume is constant (ie. a measured sample in a tube).
All I am saying is that this is not trivial measurement technology that can be implemented cheaply at this time. This could change in the future but don't hold your breath. I never said it couldn't be done though.
Look at the accuracy.I found something that might work in brewing (here), but is still very pricey at ~$995,
The 4-20 mA output represents the measured value you can read into an analog module, chart recorder or any other mA input control device, not used to turn on a common off the shelve relay directly.It also has a 4-20 mA output to trigger a relay or something (when a setpoint is reached, I assume).
From what I understand, refractometers aren't very accurate with alcohol present so they're not able to be used after/during fermentation. ...
Look at the accuracy.
Accuracy: better than 5% of span
The 4-20 mA output represents the measured value you can read into an analog module, chart recorder or any other mA input control device, not used to turn on a common off the shelve relay directly.
If we use 40 Brix span for example : 4 mA = 0 Brix, 8 mA = 20 Brix, 20 mA = 40 Brix
All my temperature controllers have the 4-20 mA output.
Cheers,
ClaudiusB
Formula for compensation of ethanol effect on refractometer: SG=1.001843-0.002318474(OB)-0.000007775(OB^2)-0.000000034(OB^3)+0.00574(AB) +0.00003344(AB^2)+0.000000086(AB^3)
I've read some papers on utilizing RF frequencies to determine the ABV% and sugar amounts in wine.
Essentially, you pick two different frequencies; one that is heavily attenuated by sugars, and one that is by alcohol. You construct some waveguides that have little holes in them to let fluid fill in. You measure the loss with nothing in it or just water as a cal, and then you dunk it in the tank.
Presto! Sugar and ABV measurements!
I looked up the oscillators for the frequencies necessary, and you can get some surface mount devices for ~$30 each. Two frequencies, so $60 right there.
I think that you could machine some waveguide or something that would work on this scale for somewhat cheap (~$20?).
Then you'd need a power meter on the far end...I think that surface mount versions of those are like $20 also.
All in all you're talking about ~$150 or so if you can pull everything off relatively cheaply. But it would tell you ABV also....that might make it worthwhile :rockin:
You'd have to get a little creative with the waveguide; the lower frequency is in S-Band, so a standard waveguide would be about the diameter of a pringles can. The higher frequency is in X-Band, so the diameter would be about a third....I'm sure that with a little research, a novel solution to that problem could be found though......a coaxial waveguide structure? Gap plates? Dielectrically load a portion of the waveguide?
Two wrapped dipoles that you can paste to your carboy/bucket, calibrate and then fill with liquid (the user would have to enter the distance between the antennae). Lots of interesting ideas...I may not sleep tonight now!!!!
If you're interested, I can shoot the paper your way.
EditL Spectroscopy might be another way....I know that they make pretty cheap devices for alcohol (couple hundred bucks), but I don't know of anything that would work for sugars....I'm not sure that there's a fingerprint for sugars in the near IR region...
I am an EE. I am interested in the paper. It sounds interesting and definetly feasible but the commercial market for such a device sounds limited especially at the price it would fetch. The NRE costs for a device like this are not trivial and of course would be built in to the price of the device making it fairly expensive not to mention the cost of the parts and manufacturing.
Formula for compensation of ethanol effect on refractometer: SG=1.001843-0.002318474(OB)-0.000007775(OB^2)-0.000000034(OB^3)+0.00574(AB) +0.00003344(AB^2)+0.000000086(AB^3)
I'll send you the paper when I get back home this evening. If you have an IEEE membership to the Antennas & Propagation Society, you could do a search for it and find the paper in their archives.
It would also be nice if it had the ability to monitor more than one beer at a time. So you could just hit a button and scroll through up to say 4 beers at any given time.
I am new to homebrewing. On Sunday I broke my hyrometer and cut my hand, blood everywhere, pretty nasty. I googled hydrometer and this thread popped up. I would gladly pay to have something safer and easier to read. Baron, Any progress on this?
Cool, I will check out the refractometer idea. Also, I found this website -sounds like exactly what I want. Anybody know anything about this?
http://fermonitor.com
It looks like someone came up with a sensor back in 1990 but nothing ever came of it:
Date: Thu, 5 Apr 90 10:21:10 PDT
From: c9a-aa at dorothy.Berkeley.EDU (Todd Matson)
...
Todd Matson / c9a-aa at dorothy.berkeley.edu
I really hope something comes of this. Some really cool monitoring could be done if this product does what its claiming to.Cool, I will check out the refractometer idea. Also, I found this website -sounds like exactly what I want. Anybody know anything about this?
http://fermonitor.com
Looks like this would do the trick...
http://www.densityanalytics.com/
it seems that this is just a cylinder (probably sealed) with a hall sensor on one end, float on the other and spring between them. Or a float on top, weight on bottom and spring in the middle. Calibrate the float/weight and spring well enough and you have a simple digital hydrometer. Anyone try this or something similar?
I will be working on a project for school that will include a data logging digital hydrometer. My current plan is to use a stainless steel object of known weight and volume immersed in the beer, and attached to a strain gauge. Using Archimede's Principle the density of the beer can be calculated based on the weight of the object in beer. Whether or not this works will depend greatly on the sensitivity of available affordable strain gauges (or whatever else I may be able to use to measure weight). I've gone through a number of different ways to approach the problem of automatically measuring SG over time while collecting data, and this seems to be the best approach thus far.
It will be a while before I have any more concrete information on the project, so don't get your hopes up yet! :cross:
I will be working on a project for school that will include a data logging digital hydrometer. My current plan is to use a stainless steel object of known weight and volume immersed in the beer, and attached to a strain gauge. Using Archimede's Principle the density of the beer can be calculated based on the weight of the object in beer. Whether or not this works will depend greatly on the sensitivity of available affordable strain gauges (or whatever else I may be able to use to measure weight). I've gone through a number of different ways to approach the problem of automatically measuring SG over time while collecting data, and this seems to be the best approach thus far.
It will be a while before I have any more concrete information on the project, so don't get your hopes up yet! :cross:
I have been working on something very similar for a brewery automation project (because i can, and like to learn)
So far I have run some calculations for using copper pipe for a weight, and low cost hanging scale (stripping the sensor out) would give me reasonable accuracy (0.01 SG), at this point i am looking at using it in the boil kettle to set boil off to hit my OG....i have yet to find a way to compensate for the bubbles though i have a work around for my situation.
I was looking at <$50 for the sensor, and everything else will tie into my control system (embedded ardunio thing)
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