Blue tooth sensor for Pez Dispenser

[geg250]

I know this is out there but I am helping my girlfriend's middle school kid on a project. He is trying to build a sensor in a Pez candy dispenser to know how many candies are left as it dispenses. He wants to put in blue tooth and app it to his phone. Any suggestions for the Pez end? It is just a spring loaded slide that moves up as you remove more candy. For those who are not familiar with a Pez candy, the image is below.

 

[jraef]

What's the budget? If unlimited, an LVDT could suffice. Highly unlikely however that he will want to spend hundreds of dollars to find out something that can be ascertained by simply looking at it instead of his smart phone...


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[geg250]

I want something fairy inexpensive but this is just an experiment for his class for the internet of things. Just wondering what could be modified for a sensor.

 

[ScottyUK]

Long travel linear pot and an A/D converter. Deal with the rest in software.

 

[geg250]

I would attached it on the side and thus the base plate would travel up and record position? What about a spring base tension reader at the base?

 

[ScottyUK]

Some are designed like a small piston and could read the position directly through the base. Something like

http://www.farnell.com/datasheets/25549.pdf

perhaps.

 

[itsmoked]

Use a V shaped piece of foil running up the side and a metal slug at the bottom. Use the CPU to measure the capacitance of the foil. As the slug rises it will vary in a linear manner.


Keith Cress
kcress -

http://www.flaminsystems.com

 

[geg250]

What about a tension sensor at the bottom of the shaft that can be calibrated depending on how much candy is loaded?

 

[jraef]

Use a V shaped piece of foil running up the side and a metal slug at the bottom. Use the CPU to measure the capacitance of the foil. As the slug rises it will vary in a linear manner.

Elegant, simple, cheap, I like it!

Geg250,
If anything ever comes of that, you need to make sure to cut Keith in on a piece of the action.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[waross]

Counter?

Bill
--------------------
"Why not the best?"
Jimmy Carter