A RaspberryPi/kegerator project

[imark]

http://www.raspberrypi.org/archives/3841 got me thinking....If you had some way of measuring the weight of the keg you'd know how much you'd left.

[Shane Phelan]

While the weight of the keg would work best, you can get flow meters for a lot cheaper. Just start with ~19L and the flow meter will subtract from that regardless of glass size. I have to say that the interface on the application in your link is amazing.

[Padraic]

I'd love a setup like that!

[Hop Bomb]

My programmer mate mentioned a Raspberry pi and flow meter when he saw my finished keggerator. Nerds are great.

[Metattron]

This may be more like it:

https://kegbot.org/

Now, where's my soldering iron...

[imark]

That kegbot is deadly!

[JimmyM]

http://www.raspberrypi.org/archives/3841 got me thinking....If you had some way of measuring the weight of the keg you'd know how much you'd left.

I started work on a keg weighing device a good while ago.
Needless to say i never finished it. I documented my progress in a thread on beoir as far as i remember.
Also, needless to say, it got shelved when i got bored and had higher priorities

It was basically a hacked electronic scales hooked up to an AVR processor (same chip used in an arduino)

(Insomnia cure alert!!)
Here's what i did. Took the scales apart to reveal a strain gauge arranged in a wheatstone bridge. Basically applying weight to the strain gauge causes the resistance to change meaning you get a very small voltage change that you can measure with your microcontroller. Since its so small you need to amplify the signal using an op amp.
I was reading it in and cant remember whether i had successfully converted the output from above to digital using the AVR - this task would be alot easier using arduino and its built in framework vs using the bare chip as i was doing. (Think of it as all-grain vs a kit)

So basically its the price of a cheap electronic scales (aside from the microprocessor) and a suitable op-amp. ~15 euro.

Flow meter is a neater solution. Weight of the beer depends on gravity - the weight of the keg when its empty would need to be taken account too and this could change for diff kegs. With a flow meter there is nothing like that to worry about other than knowing the amount you started with in the 1st place - so that you know you're getting near the end.

[Will_D]

Flowmeters from .nl are not cheap tho' $60 + $20 postage!!

[Metattron]

Get a flowmeter on aliexpress for about $12.  Had a look around the other day and couldn't find anything else close.

http://m.aliexpress.com/item/808817606.html