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measuring jug for the blind

M

mimet66

Jan 1, 1970
0
hi all!
my project is to build a measuring jug for the blind.this jug can sense
certain water level for example at 250ml,500ml etc using some kind of a
sensor.i'm thinking of using an existing kettle with little floating thing
that tells the water level.but i don't know what suitable sensor to use to
detect this floating thing.i'm thinking of using infrared sensor.when the
floating thing passes the sensor at certain level,it will make sound.
 
C

Chris

Jan 1, 1970
0
hi all!
my project is to build a measuring jug for the blind.this jug can sense
certain water level for example at 250ml,500ml etc using some kind of a
sensor.i'm thinking of using an existing kettle with little floating thing
that tells the water level.but i don't know what suitable sensor to use to
detect this floating thing.i'm thinking of using infrared sensor.when the
floating thing passes the sensor at certain level,it will make sound.

Liquid level can easily be determined by attaching a float to a dancer
arm, have the dancer arm turn a potentiometer with a reference voltage
applied, or by connecting it as a rheostat, applying a reference
current, and then reading the voltage.

If you want to visually detect the position of a floating object,
you'd probably need an array of LEDs in a line, and float level would
be dependent on which was the highest one that was off.

You could also use ultrasonics to determine the distance of the water
level from the ultrasonic transducer.

However, each of these has a basic flaw -- it's difficult to have
something in the jug without being able to clean it. Much more
trouble than it's worth.

As a practical matter, this is usually either done by weight, or by
tapping the jug and listening for the tone (which will rise as the jug
becomes more full).

If this is a school project, you might want to describe in some detail
what the class requirements are. It's possible you could hone this up
into something that might get a good grade.

But as a practical matter, I'd guess there isn't a lot of potential
here.

Good luck
Chris
 
M

mimet66

Jan 1, 1970
0
hi chris.
i was given this topic 'innovations for special people' for my project.i
picked up this idea from this product,
http://www.cobolt.co.uk/cobs/product.asp?dept_id=2&pf_id=Jug

i prefer using the visually detect the position of a floating object
method.my kettle has this floating object at the side to indicate water
level.so i have to put sensors on the outside of the floating indicator.i
think this method does not need any device at the inside of the jug.

how about the electro-optic type sensor?is it expensive.i found it on this
site.
http://www.gemssensors.com/content.aspx?id=282
 
C

Chris

Jan 1, 1970
0
hi chris.
i was given this topic 'innovations for special people' for my project.i
picked up this idea from this product,http://www.cobolt.co.uk/cobs/product.asp?dept_id=2&pf_id=Jug

i prefer using the visually detect the position of a floating object
method.my kettle has this floating object at the side to indicate water
level.so i have to put sensors on the outside of the floating indicator.i
think this method does not need any device at the inside of the jug.

how about the electro-optic type sensor?is it expensive.i found it on this
site.http://www.gemssensors.com/content.aspx?id=282

This little ASCII diagram shows the idea behind the Gems opto sensor
you link (view in fixed font or M$ Notepad):

|
| Photo
| | Trans.|
| | LED - -|
| | ->|- \ ^ |
| | | --- |
| | | | |
| | V | |
| | | ^ |
| | | | |
| | | | |
| | | ^ |
| | V | |
| \ | | /
| \ | |/
| \'-->--'
| \ /
| \ /
| \
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

The LED sends light down to the apex of the cone. If there's no
liquid on the plastic, nearly all of the light will reflect off the
inner surface of the cone, and bounce back to the phototransistor as
shown (kind of -- sorry, this is a newsgroup ;-). However, any liquid
will change the optical characteristic, causing most of the light to
go through the clear plastic cone into the liquid. Hence, level
detect.

Now, in order to use this scheme, you'll need several of these
sensors. In addition, these are not rated as food-safe, which means
you can't sterilize the surface without damaging it. Gems makes some
other sensors which will do the job, but they're significantly more
expensive.

If you're trying to do opto level detection on the cheap, you'll
probably be best off with multiple LEDs and multiple photoransistors.
You can look through a clear jug that way. By turning on one and only
one LED at a time, and only looking at the phototransistor output
directly opposite, you can get a clear idea if something is
obstructing the view. And all of the LEDs plus all of the
phototransistors shouldn't cost more than one of these Gems switches.

Looking at the device you linked in the Cobolt catalogue:

http://www.cobolt.co.uk/Catalogue2006.pdf

I get the feeling that it's actually a scale. Note that you have to
calibrate it for different types of liquids, and it's also capable of
measuring solids with user-defined functions. This seems to be the
easiest way to "skin the cat", and I'm fairly sure it's the method
they use.

If you wanted to do this, you'd have to build a scale around a
removeable jug in such a manner that it was watertight, the jug would
rest freely on the scale base when it was resting, and also that the
jug would be removeable for easy cleaning. Not so difficult to put
together, if you've got access to a microcontroller development kit.
Also, the "talking" function could be done with one of the ISD talking
chips without too much difficulty.

Now for the hard part -- fess up. This is a school project, no?
You'll get better advice if you can be clear about what you need.

By the way, it's almost midnight in this time zone -- if you need a
response, I'll try to post again in about 6 or 7 hours.

Good night
Chris
 
Y

Yukio YANO

Jan 1, 1970
0
mimet66 said:
hi chris.
i was given this topic 'innovations for special people' for my project.i
picked up this idea from this product,
http://www.cobolt.co.uk/cobs/product.asp?dept_id=2&pf_id=Jug

..my kettle has this floating object at the side to indicate water
level.so i have to put sensors on the outside of the floating indicator.i
think this method does not need any device at the inside of the jug.

how about the electro-optic type sensor?is it expensive.i found it on this
site.
http://www.gemssensors.com/content.aspx?id=282
This is supposed to for a BLIND individual !!!

The Answer is a Top Loaded Balance or Weight Scale with an Audio
Read-out with a Tare mode

With a Maximum of 5 Kg./10 pounds, sensitive to 5gm./0.1 ounce

In Use: You would Tare or Zero the Scales to the weight of the Jug or
container then fill until it sounds right, then confirm the "Fill" by
re-weighing the container and measure the weight by "Hearing the
Readout". Or just pour the liquid being measured into the jug and listen
to the Read-out as the liquid is being dispensed .

Yukio YANO
 
E

Esther & Fester Bestertester

Jan 1, 1970
0
With a Maximum of 5 Kg./10 pounds, sensitive to 5gm./0.1 ounce

Yeah, but will it be accurate when measuring out liquid nitrogen?
BFt
 
Y

Yukio YANO

Jan 1, 1970
0
Esther said:
Yeah, but will it be accurate when measuring out liquid nitrogen?
BFt
I don't see any problems, Yes I have used Liquid Nitrogen on several
instruments for several years.

Yukio YANO
 
G

Grey

Jan 1, 1970
0
mimet66 said:
hi all!
my project is to build a measuring jug for the blind.this jug can sense
certain water level for example at 250ml,500ml etc using some kind of a
sensor.i'm thinking of using an existing kettle with little floating thing
that tells the water level.but i don't know what suitable sensor to use to
detect this floating thing.i'm thinking of using infrared sensor.when the
floating thing passes the sensor at certain level,it will make sound.

I have seen commercial units for this exact purpose. The unit is in a small
box/enclosure which hangs over the side of a cup with two wires. Water
conatct, closes circuit, buzzer rings. I good design would be to have AC
voltage on the probes to prevent plating with time. Similar units are used
for bath tubs, sinks etc.

Graham
 
R

Rich Grise

Jan 1, 1970
0
hi all!
my project is to build a measuring jug for the blind.this jug can sense
certain water level for example at 250ml,500ml etc using some kind of a
sensor.i'm thinking of using an existing kettle with little floating thing
that tells the water level.but i don't know what suitable sensor to use to
detect this floating thing.i'm thinking of using infrared sensor.when the
floating thing passes the sensor at certain level,it will make sound.

How about a float with a stick on top, through a hole in the top of the
jug, (a la hydrometer) that the blind person can "sense" by simply feeling
it?

Admittedly, it's not very electronic or hi-tech, but shouldn't the first
question be, "What works?"

Good Luck!
Rich
 
C

christopher

Jan 1, 1970
0
my project is to build a measuring jug for the blind.this jug can sense
certain water level for example at 250ml,500ml etc using some kind of a
sensor.i'm thinking of using an existing kettle with little floating thing
that tells the water level.but i don't know what suitable sensor to use to
detect this floating thing.i'm thinking of using infrared sensor.when the
floating thing passes the sensor at certain level,it will make sound.

Hello,

I found this piezo-resonant fluid level sensor in a technology
magazine I received today and remembered your post. It could give you
ideas even if you don't buy one.

http://www.gemsmedicalsolutions.com/template.aspx?id=36

Good Luck,

* * *
Christopher

Temecula CA.USA
http://www.oldtemecula.com
 
J

jasen

Jan 1, 1970
0
It may be possible to cause air to blow across a "penny-whistle"
that's tuned by the water level instead of a manual plunger.
the pitch of the sound will indicate the water level.

A filling tube that extends to the bottom of the jug may be all
that's needed, if it's rigid enough you should get the "bottleneck filling"
sound as water is added, again the pitch of the sound will indicate the
water level.

Another option would be regulating the flow rate of the water so that the
user merely has to count eg. five seconds for each cup.

I find I can judge the level of fluid in a spray can fairly well just by
sloshing it

Bye.
Jasen
 
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