Will do. I hadn't planned on posting anything until I had something more concrete other than some math and an idea that it "should work", but then this thread was revived. After all, my idea may end up as vaporware just like so many of these plans.
Digital Hydrometer
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Will do. I hadn't planned on posting anything until I had something more concrete other than some math and an idea that it "should work", but then this thread was revived. After all, my idea may end up as vaporware just like so many of these plans.
I am both a brewer and a winemaker. I'd like to find a way to get SG data into my PC every 30 minutes during fermentation. This would have lots of advantages in wine making. Automating and logging the samples is straightforward. Where I am stuck is in finding a low cost way to obtain the SG data in some type of electronic form. I see expensive systems out there, but if I can figure out how to collect the SG information, designing/building the rest of it should be easy. Does anybody know if a specific gravity "sensor" exists?
jpalarchio
Well-Known Member
Look into the "Brew Bug"; it seems to be designed to just that. Doesn't appeared to be fully released to production yet but it might give you some ideas if you're looking to come up with something of your own.
The way I imagine this working best is not actually a SG sensor but rather a floating hydrometer of sorts that is electronically measured. Determining the distance of the hydrometer above/below the liquid line should be achievable.
Mrcrowley269
Well-Known Member
I am very interested...this would be a great tool. Am going to check into the brew bug as well.
Got a link for that, all I can find on google is people talking about being bit by the brew bug!
Interesting idea. But, I take samples to not only check the gravity, but to taste my product as well. Now if a digital taster could be developed, and the flavors downloaded directly into my brain, sampling my beer may become a thing of the past.
thyirishmen
Well-Known Member
Def interested!
jpalarchio
Well-Known Member
Sorry, guess it would have helped if I gave the right name: "The Beer Bug".
Either way, information still seems a bit scarce although the Twitter feed was updated last month.
http://twitter.com/#!/theBeerBug (Check the images for some picture of prototypes in action)
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tophmck
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The beer bug website finally went live yesterday. Looks like the price point will be $99 for the ThermoBug (temperature only), $119 to test a prototype BeerBug (temperature and specific gravity), and $199 for a production BeerBug. Apparently they're launching a KickStarter page next month (I don't think they've announced yet when they're planning to ship).
rmaloney86
Well-Known Member
Want it!
Don't know if it is my browser but that website is seriously bad, reminds me of chugger's when he first opened. Missing links, missing photos, I couldn't even "buy" the thing. It looks like an interesting concept but it will be hard to get people to buy/trust the technology if the website has these issues.
Anyone got a link to the brew bug patent application? I really want to see how they are doing this.
lunchbox
Well-Known Member
I had the same problem, and I really want to buy one of these.
Erroneous
Well-Known Member
IDK if this is what brew bug uses, and kind of doubt it based on the pictures posted on their Parent Comany's Facebook Page but this could be a decent patent. Seems complex though, and this brew bug looks pretty simple at least in one picture.
Edit: I've also found this one which seems more likely. Still, it'd really help to know the inventor's name. No help from DNS whois records.
Erroneous
Well-Known Member
Based off what I can gather from the 2 facebook images, the beer bug uses a sealed and specifically weighted electronic hydrometer that is likely suspended from the top of the fermentation vessel. Give it a starting gravity and it uses a hall sensor to tell how far away the end of its pole it and can estimate the gravity. The devices on top of the fermentor pictured are likely only the data loggers with an extra air hole to allow co2 to escape while in a carboy. If that is what the beer bug is then I'm curious as to whether or not krausen affects it. I'd also guess it'd be useless in situations requiring a blowoff tube.
Erroneous
Well-Known Member
beermaker72
New Member
My inside source says the wireless temp sensor is a done deal - not that difficult. But, the wireless specific gravity is another thing altogether. They really can't even make it work at all in a fermentation. Truth is, none of the group knows diddly about making beer. Another thing I have heard is they are planning to use Kickstarter to raise money for developing the specific gravity sensor. You ready to donate?
beermaker72
New Member
Actually, it is just a digital hydrometer. Works just like a glass hydrometer except it provides a digital result. Just floats in the liquid at a depth that is dependent upon the density of the liquid. Sounds great until you introduce gas bubbles, foam, solids, blow-off... all the stuff that happens in a fermentation... Here is a link to a photo of the beerbug showing it pretty clearly http://www.facebook.com/photo.php?fbid=237635179632443&set=a.237635136299114.61564.199014980161130&type=1&relevant_count=3
Erroneous
Well-Known Member
Right, use a hall sensor to figure out depth. It's been discussed on this thread before.
From what I have read that was the first prototype which has been abandoned (I think because of the issues you mentioned!)
No idea how the new prototype works as it sits in the airlock bund/groumet and they are keeping the bit in the wort (if there is one) very secret.
beermaker72
New Member
Interesting. If it was abandoned they just did it this week. The thing you see that attaches to the bung is just the receiver/transmitter/memory module. They didn't want all those electronics to be inside the beerbug, would complicate a number of things. I hope they don't try bubble counting, seen that goat-roping once before.
Hahaha, that makes sense (both why the did it and why they are not showing more pics of the "inside" device).
I would still want to see someone try measuring the SG by a differential pressure sensor and 2 tubes of different lengths submerged in the wort. With a set distance it should be easy enough to work out the gravity, just rearrange "P = specific gravity * vertical tube seperation (in mm)* gravatational constant (9.81)"
And make the tubes big enough so they don't get blocked.
sharpk60
Member
mattd2: I tried out the differential pressure sensor idea a few years ago. It has potential but you need a VERY sensitive pressure sensor (which also makes the sensor expensive). Anyway, I posted my experimental results with an inexpensive Freescale pressure sensor here: http://sharpk60.blogspot.com/search/label/specific_gravity
I also spent some time playing with the bubble counting technique and gave up on it pretty quickly.
I also spent some time playing with the bubble counting technique and gave up on it pretty quickly.
stevegutteridge
New Member
Here are some possible ideas I had for a SG sensor:
Refractive index. The refactive index of a sugar solution varies with the concentration. A V-shaped notch in a block of clear plastic/glass forms a prism with the liquid in the gap. A CCD image sensor on one side measures the displacement distance of an LED-illuminated image/pattern on the other side.
Resistance. Sugar solutions conduct electricity. Measure the change in resistance across a fixed distance.
Speed of sound. The speed of sound in a liquid varies with its density. Use an ultrasonic transducer to emit a sound pulse and measure the time delay before the pulse is received a fixed distance away.
Polarisation. Sugar solutions rotate the plane of polarised light. Measure the light received from an LED after it has passed through two cross-polarised filters with the liquid in between them.
Viscosity. Measure the time taken for a steel ball bearing to fall a known distance inside a short glass tube that is only slightly wider than the ball. An electromagnet lifts the ball whereupon it bridges two contacts to close a circuit. On release, the circuit opens and timing commences. On reaching the bottom, the ball again bridges two contacts to close a circuit and stop the timer.
I haven't done any tests or calculations to work out how sensitive or accurate any of these methods might be. I simply present the ideas here for further discussion.
Note that most (all?) of these methods will probably produce different results according to temperature, so that also needs to be measured and taken account of.
Refractive index. The refactive index of a sugar solution varies with the concentration. A V-shaped notch in a block of clear plastic/glass forms a prism with the liquid in the gap. A CCD image sensor on one side measures the displacement distance of an LED-illuminated image/pattern on the other side.
Resistance. Sugar solutions conduct electricity. Measure the change in resistance across a fixed distance.
Speed of sound. The speed of sound in a liquid varies with its density. Use an ultrasonic transducer to emit a sound pulse and measure the time delay before the pulse is received a fixed distance away.
Polarisation. Sugar solutions rotate the plane of polarised light. Measure the light received from an LED after it has passed through two cross-polarised filters with the liquid in between them.
Viscosity. Measure the time taken for a steel ball bearing to fall a known distance inside a short glass tube that is only slightly wider than the ball. An electromagnet lifts the ball whereupon it bridges two contacts to close a circuit. On release, the circuit opens and timing commences. On reaching the bottom, the ball again bridges two contacts to close a circuit and stop the timer.
I haven't done any tests or calculations to work out how sensitive or accurate any of these methods might be. I simply present the ideas here for further discussion.
Note that most (all?) of these methods will probably produce different results according to temperature, so that also needs to be measured and taken account of.
Erroneous
Well-Known Member
I'm back on the idea of simply weighing the fermentor throughout fermentation. Firstly, you'd have to weigh it empty. Then add your wort and tell it what the SG is (takes out need to know volume). Then it keeps track of the weight, as co2 is lost and SG goes down so does the weight. The advantage of this is that you don't need to know the temperature AND it can tell you the actual volume.
I ran some numbers. For this $10 sensor you can measure up to about 110 lbs. If you calculate the difference of 0.001 SG on 5 gallons of water, the weight difference is about 0.042. Divide 110 by 0.042 and you get 2619. This is the number of increments you'd need to accurately detect the difference of 0.001 SG. Now then, just get a microcontroller that can give you 2048 on the voltage divider circuit and you will be good within about 2 gravity points, and throw in the accuracy of the sensor. But it should give you a good idea as to where you're at.
But here's my only problem: how to detect weight of dissolved co2 in the solution? Would it affect the weight enough to throw it off? Also, shouldn't I subtract the weight of yeast that has fallen out of solution?
I ran some numbers. For this $10 sensor you can measure up to about 110 lbs. If you calculate the difference of 0.001 SG on 5 gallons of water, the weight difference is about 0.042. Divide 110 by 0.042 and you get 2619. This is the number of increments you'd need to accurately detect the difference of 0.001 SG. Now then, just get a microcontroller that can give you 2048 on the voltage divider circuit and you will be good within about 2 gravity points, and throw in the accuracy of the sensor. But it should give you a good idea as to where you're at.
But here's my only problem: how to detect weight of dissolved co2 in the solution? Would it affect the weight enough to throw it off? Also, shouldn't I subtract the weight of yeast that has fallen out of solution?
sharpk60
Member
There was a pretty good thread on weight based measurement here. It even includes a good spreadsheet that takes into account the temperature and dissolved CO2.
I was able to replicate the results with very good accuracy. The only problem I found with this approach was that if you leave the carboy on the scale or weight sensor the reading will drift over time. I think this is a well-known issue that's linked to the sensor physically deforming over time (kind of like a spring that is under tension will stretch over time). So to get accurate results you have to put the carboy on the scale, take a reading, then remove it it from the scale. This adds some complexity if you want to take readings automatically. If you're fine with manually putting the carboy on and off the scale then this is a great way to measure gravity without having to unseal the carboy.
I was able to replicate the results with very good accuracy. The only problem I found with this approach was that if you leave the carboy on the scale or weight sensor the reading will drift over time. I think this is a well-known issue that's linked to the sensor physically deforming over time (kind of like a spring that is under tension will stretch over time). So to get accurate results you have to put the carboy on the scale, take a reading, then remove it it from the scale. This adds some complexity if you want to take readings automatically. If you're fine with manually putting the carboy on and off the scale then this is a great way to measure gravity without having to unseal the carboy.
Erroneous
Well-Known Member
Interesting. Well maybe an air pump that fills a bladder to lift it off the sensor...or a servo...or just a better sensor maybe...
LordUlrich
Well-Known Member
Creep of the sensor body (what is causing the drift) should be pretty minor over the short time a fermentation happens if you are not near the elastic limits of the sensor. So if you re zero the scale every fermentation and keep below say 20% of the rated max it should not be a problem.
Erroneous
Well-Known Member
Well then I guess we'd need a bigger sensor. This one is rated for 120 lbs, so probably fine for 3 gallon batches but nothing larger.
LordUlrich
Well-Known Member
Keep in mind you will not be putting the whole weight of the batch on one sensor... you need yo build a platform and either use multiple sensors or support the other edge in some way that is not fixed. A hinge would work, then you are supporting about half of the weight with the sensor. You will need to calibrate accordingly.
When looking for a sensor check local stores for cheep digital bathroom scales. I picked up one with 4 sensors for $5 same the specs are similar to the sparkfun sensor (from my testing). If it can save you a few bucks you can spend that on a better amplifier which will have more impact on the quality of readings for a cheep load cell than the specific cell. (Cheep for load cells is <$100 each)
When looking for a sensor check local stores for cheep digital bathroom scales. I picked up one with 4 sensors for $5 same the specs are similar to the sparkfun sensor (from my testing). If it can save you a few bucks you can spend that on a better amplifier which will have more impact on the quality of readings for a cheep load cell than the specific cell. (Cheep for load cells is <$100 each)
sharpk60
Member
Lord Ulrich: That's a good point about the limits of the sensor. I think I had 60 pounds fully on a sensor rated at 75 pounds max and it drifted within minutes. I haven't tried it with a sensor rated for a much higher maximum.
Or I could try it as you suggested and put the carboy on a hinged platform so that only a portion of the weight is supported by the scale.
Or I could try it as you suggested and put the carboy on a hinged platform so that only a portion of the weight is supported by the scale.
FuzzeWuzze
I Love DIY
So, found this thread when investigating digital hydrometers like many others and was curious...
Has anyone used the Hall effect and displacing a magnet in some sort of float tube? As the density gets lower, the magnet would drop vertically and get further away from the Hall sensor...
Just trying to figure out how the beer bug is doing it with their torpedo for a low price (relative to industrial ones).
After reading this products description and how it works, it seems feasible?
http://www.gardco.com/pages/density/electric_hydrometer.cfm
Has anyone used the Hall effect and displacing a magnet in some sort of float tube? As the density gets lower, the magnet would drop vertically and get further away from the Hall sensor...
Just trying to figure out how the beer bug is doing it with their torpedo for a low price (relative to industrial ones).
After reading this products description and how it works, it seems feasible?
http://www.gardco.com/pages/density/electric_hydrometer.cfm
sharpk60
Member
FuzzeWuzze: I tried out the hall effect + magnet approach too. It seems like it should work, but there are some things that are tricky about it:
1) With a strong rare earth magnet a typical hall effect sensor has a range of around 1.5 inches, which is much less than the full movement of a typical hydrometer float. There are probably ways to eek out more range with different magnets or configurations, but I don't think the effective range is going to be significantly more than this. This means you probably have to design your own float that will have a smaller range of movement (as they did for the Gardco sensor).
2) Keeping everything food safe is a pain. If you have a hall effect sensor floating in the wort alongside the float you have to keep everything sealed up securely so as not to contaminate the wort or destroy the electronics.
3) If you go the other route and have the sensor mounted in a fixed position (maybe even outside the carboy) then you have to worry about accounting for the liquid level in the carboy.
This isn't to say it's not possible (as proven by the link you posted), it's just not easy.
1) With a strong rare earth magnet a typical hall effect sensor has a range of around 1.5 inches, which is much less than the full movement of a typical hydrometer float. There are probably ways to eek out more range with different magnets or configurations, but I don't think the effective range is going to be significantly more than this. This means you probably have to design your own float that will have a smaller range of movement (as they did for the Gardco sensor).
2) Keeping everything food safe is a pain. If you have a hall effect sensor floating in the wort alongside the float you have to keep everything sealed up securely so as not to contaminate the wort or destroy the electronics.
3) If you go the other route and have the sensor mounted in a fixed position (maybe even outside the carboy) then you have to worry about accounting for the liquid level in the carboy.
This isn't to say it's not possible (as proven by the link you posted), it's just not easy.
CSI - CandiSyrup
Well-Known Member
I thought this problem had been solved with inline density meter's. They mount sub-miniscus below the surface:
http://www.eepowersolutions.com/products/dm-series-inline-density-meters-online-process-control/
Since the output is 32 bit, it could easily be modified to log the pushed data to an SD card using a Spider Kit:
https://www.ghielectronics.com/catalog/product/297
pablosbrewing
Well-Known Member
CSI - CandiSyrup
Well-Known Member
"Call for Quote" means you cannot afford it. Best price I can find on that meter is $6,549
Got it...cost is the key factor. That would definitely be prohibitive for a home brewer
stever1000
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Any recent info on this? Very interesting thread
