Liquor Level Detect via Computer

[Kcarpenter]

Hey there.

This is my first post to the boards. I did do a search and couldnt find this specific hardware...

I want to be able to detect when liquor level that is in a 36 ounce gets below a certain level.

I also want a computer application to run the check every few minutes or whenever I specify.

I can't find anything like this and will it corrode and release chemicals/whatever into the liquor?

Thanks!

 

[blueroomelectronics]

What about weight?

 

[Kcarpenter]

I never thought of that...That will work perfectly. Do you know of such a device?

Thanks!

 

[Kcarpenter]

I should also provide that I need 16 instances if the chosen method....So price it a factor.

Thanks again.

 

[Leftyretro]

I never thought of that...That will work perfectly. Do you know of such a device?

Thanks!

It is the best method, as there is no contact with the bottle contents and can be quite accurate once calibrated, you have to factor out the weight of the empty container, called the tare weight.

Search on load cells and/or strain gauges. Commercial devices are somewhat pricey but used on E-bay or surplus outlets can be cheap. A load cell is just a variable resistor(s) that changes resistance depending on the physically force being felt by the device. They are usually wired to a resistance bridge circuit for proper sensitivity and balance adjustments. They usually require DC amplification for useful measurment. After that a simple A/D function on a microchip could then display the amount and or generate an alarm when a certain weight is reached.

Load cells come in a tremendous range, from grams to tons, so finding a cell having the range you need is the first order of business.

 

[Voltboy]

Or if you want to go back to detecting the fluid just use a float switch.

 

[mneary]

You could save some money by using one load cell and 16 detectors that sense a bottle absent. Might be difficult to keep track if multiple bottles are removed at the same time, but depending on your accuracy goals it might be acceptable.

 

[kchriste]

You could also use the capacitive method. You would put two foil strips on the side of the glass and measure the capacitance between them. The capacitor is formed with the liquid and the two strips so the capacitance is proportional to the liquid level. A person's hand on the glass could mess it up though.

 

[Kcarpenter]

The jugs are all plastic...I also need to measure/weigh each jug to determine when that specific one is almost empty.

kchriste, will this still work?

Thanks for the reply's everyone!

 

[kchriste]

kchriste, will this still work?

Yes, it will still work with plastic containers. As long as the container is an insulator (Not metal) and the liquid is a partial/full conductor, the capacitive method should work. The weight method will work with any type of container or liquid but the sensor will be more expensive than a couple of strips of foil.

 

[Kcarpenter]

and how will this interface with a computer?

 

[kchriste]

It depends on what interface is available on the computer. The choice is really yours: Parallel, serial or USB ports. Either way, you'll probably need a microcontroller do the capacitance reading and communicate the data via one of the above interfaces.
Here is a wireless method, but no computer interface. It does explain one way to do this with RFID devices:
https://www.electro-tech-online.com/custompdfs/2007/10/TR2002-21.pdf

If you want something really simple you could do this: Make a spring loaded platform with a microswitch under it. You design it with just enough spring tension so that the platform rises and the microswitch toggles when the weight on it falls below a set level. The microswitch could be connected across one of the handshake lines on a serial port. To do multiple switches we are back looking at a microcontroller again to minimize the number of serial ports you would need. You could also use the parallel port as it would handle more switches per port.

 

[KMoffett]

This is a non-contact liquid level detection circuit based on a Q-PROX QT114 IC. Two foil strips are placed around the non-conductive (i.e. glass or plastic) container. The trip point will be at about the top of the lower foil. The output at pin-2 switches from +5v to 0V when the level drops below the trip point. You will need to find a circuit/module/interface that lets your computer detect this logic level change. The pot is used to adjust the IC to the specific foil/container/wire-length dimensions. I've used this circuit to maintain the alcohol level in a 1L lab jar, through a solenoid valve (via a driver transistor) from a gravity fed supply jar. The alcohol was evaporated by air flowing through the jar. I was never able to see the change in level, but the the solenoid would cycle to maintain the level. It's that precise. I can't help with the computer interface, not knowing what program your using. Maybe someone else can help with that part.

Ken