Cheap Pressure Sensors?
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Posts: 46,084
Hello,
I have been looking around for some cheap pressure
sensors(digi key seemed to be the cheapest), anyone
know of any good cheap ones, or even a way to "roll my
own" other than with the "black foam stuff" method
from IC chips? This is for a liquid application where
I have a some manometers built to measure the volume
indirectly via the pressure. Other methods to get the
volume(capacitance, weight, etc.)I believe will not
work as I need to test many different types of fluids
where I do not know what fluid or how much will be
added. The pressure seems to be the only fluid
invariant method, unless someone has another idea.
Thanks for any help provided,
Ross Cooper
__________________________________________________
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
http://taxes.yahoo.com/
I have been looking around for some cheap pressure
sensors(digi key seemed to be the cheapest), anyone
know of any good cheap ones, or even a way to "roll my
own" other than with the "black foam stuff" method
from IC chips? This is for a liquid application where
I have a some manometers built to measure the volume
indirectly via the pressure. Other methods to get the
volume(capacitance, weight, etc.)I believe will not
work as I need to test many different types of fluids
where I do not know what fluid or how much will be
added. The pressure seems to be the only fluid
invariant method, unless someone has another idea.
Thanks for any help provided,
Ross Cooper
__________________________________________________
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
http://taxes.yahoo.com/
Comments
Not sure what your setup is. If you don't know what the fluid is, you won't be
able to back out the volume because you won't know the density (i.e., pressure =
density * gravity * height). Am I misunderstanding your setup?
Clark Hughes
Klutch wrote:
>
levels. The sewer system here at work uses them. How cheap? I have no
idea.
--Dan
Original Message
From: "Klutch" <klutch66@y...>
To: <basicstamps@yahoogroups.com>
Sent: Tuesday, April 16, 2002 12:33 PM
Subject: [noparse][[/noparse]basicstamps] Cheap Pressure Sensors?
> Hello,
> I have been looking around for some cheap pressure
> sensors(digi key seemed to be the cheapest), anyone
> know of any good cheap ones, or even a way to "roll my
> own" other than with the "black foam stuff" method
> from IC chips? This is for a liquid application where
> I have a some manometers built to measure the volume
> indirectly via the pressure. Other methods to get the
> volume(capacitance, weight, etc.)I believe will not
> work as I need to test many different types of fluids
> where I do not know what fluid or how much will be
> added. The pressure seems to be the only fluid
> invariant method, unless someone has another idea.
> Thanks for any help provided,
> Ross Cooper
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Tax Center - online filing with TurboTax
> http://taxes.yahoo.com/
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
need?
Leroy
Klutch wrote:
>
> Hello,
> I have been looking around for some cheap pressure
> sensors(digi key seemed to be the cheapest), anyone
> know of any good cheap ones, or even a way to "roll my
> own" other than with the "black foam stuff" method
> from IC chips? This is for a liquid application where
> I have a some manometers built to measure the volume
> indirectly via the pressure. Other methods to get the
> volume(capacitance, weight, etc.)I believe will not
> work as I need to test many different types of fluids
> where I do not know what fluid or how much will be
> added. The pressure seems to be the only fluid
> invariant method, unless someone has another idea.
> Thanks for any help provided,
> Ross Cooper
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Tax Center - online filing with TurboTax
> http://taxes.yahoo.com/
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
As far as I have been able to tell, there are no inexpensive pressure
sensors that are designed to tolerate direct contact with liquids. Some will
do quite well when additional silicone grease is added to protect their
internals, however, in a recent exchange with Motorola and another sensor
manufacturer the old method of allowing a column of the liquid medium to
proportionally pressurize dry air above it still remains the standard....Of
course, the nice things about this method are that of working with a lower
pressure range, and with minimal risk of leakage.
Chris
> Hello,
> I have been looking around for some cheap pressure
> sensors(digi key seemed to be the cheapest), anyone
> know of any good cheap ones, or even a way to "roll my
> own" other than with the "black foam stuff" method
> from IC chips? This is for a liquid application where
> I have a some manometers built to measure the volume
> indirectly via the pressure. Other methods to get the
> volume(capacitance, weight, etc.)I believe will not
> work as I need to test many different types of fluids
> where I do not know what fluid or how much will be
> added. The pressure seems to be the only fluid
> invariant method, unless someone has another idea.
> Thanks for any help provided,
> Ross Cooper
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Tax Center - online filing with TurboTax
> http://taxes.yahoo.com/
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
http://sales.goldmine-elec.com/prodinfo.asp?prodid=3888
You could check at All Electronics, Alltronics, and other surplus dealers.
> Hello,
> I have been looking around for some cheap pressure
> sensors(digi key seemed to be the cheapest), anyone
> know of any good cheap ones, or even a way to "roll my
> own" other than with the "black foam stuff" method
> from IC chips?
What I am doing is building a robotic bartender.
Making drinks involves simply pouring out predefined
drink formulas(ie: 1 shot vodka, 4 shots orange juice
= screwdriver) via liquid solenoids from 16 seperate
liquid containers. I need to be able to measure maybe
2 gallons per container and be able to pour out with
an accuracy of hopefully some fraction of an ounce,
very doable I think. The velocity flow rate is a dead
linear downward slope according to the basic bernoulli
equation for fluid flow, and some trials I have
performed, but the problem is I cant just use the one
curve and fit a line to it because I have 16 seperate
fluids(at least 16 different potentially unknown
densities). I need to keep track of how much I have
poured out of the container so I know where I am along
the line(ie: 16 counters) , and I believe that this
may be too memory intensive for the stamp to deal
with, along with the other supporting devices (LCD,
EEPROM, Shift Reg. I/O expanders, Keypad, etc.). So
rather than do this, I have built a
manometer/container that I SHOULD, the operative word,
be able to very accurately measure the volume of the
fluid regardless of the fluid type in it from the
pressure. By this method I hope to avoid using all
the counters and memory, and hopefully boil it down to
just 1 measurement routine performed on each
manometer/container seperatley. Anyway, there are
more details, but that is the jist of it, and why I
need the pressure sensors, and why I would like to
minimze cost as this is all currently prototype just
to try to get the bugs and theory worked out. I
havent hashed out the fluid math yet but for a
pressure range, I assume 0<=p<=~20 PSI for the 2
gallons of fluid(assuming 8.33 lb/gal) in a 1"
diameter pipe. If any one has any input, better
method, or something to debunk my method, it would be
greatly appreciated. This originally was supposed to
be a very simple project, but as I dug in it just
spiraled, but that is ok, it has been alot of fun, and
I have learned alot from it. When, and "if", I get it
done, I hope to post it on my website so that others
wont have to stumble and fall quite as much as I have.
Ross Cooper
--- Leroy Hall <leroy@f...> wrote:
> How much quantity and accuracy do you need? What
> pressure range do you
> need?
> Leroy
>
> Klutch wrote:
> >
> > Hello,
> > I have been looking around for some cheap pressure
> > sensors(digi key seemed to be the cheapest),
> anyone
> > know of any good cheap ones, or even a way to
> "roll my
> > own" other than with the "black foam stuff" method
> > from IC chips? This is for a liquid application
> where
> > I have a some manometers built to measure the
> volume
> > indirectly via the pressure. Other methods to get
> the
> > volume(capacitance, weight, etc.)I believe will
> not
> > work as I need to test many different types of
> fluids
> > where I do not know what fluid or how much will be
> > added. The pressure seems to be the only fluid
> > invariant method, unless someone has another idea.
> > Thanks for any help provided,
> > Ross Cooper
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! Tax Center - online filing with TurboTax
> > http://taxes.yahoo.com/
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
__________________________________________________
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
http://taxes.yahoo.com/
required. Put it in an enclosure that allow fastening a potentiometer
to the shaft where you would remove the dial hand from? Might work, get
someone that only has two thumbs to build it.
Tell 'em where you got it!!!!!!!!!!
[noparse]:)[/noparse])))))))))
Leroy
it does not look like it made it, so I will strip it
down and try it again:
I am building a robotic bartender that pours drinks
from 12+ containers via solenoid valves. But because
all of the fluids are different they flow at different
rates according the the Bernoulli fluid flow equation.
I am trying to side step this problem without using
flow meters and counters and the like by trying an
indirect approach, what I have built is a manometer
that will hopefully be able to measure the pressure,
and from the pressure I should be able to determine an
estimate of the current volume empirically. As for
the density, I will have a general idea of what fluid
is in the container (kodka, gin, etc.) so I will use a
general, or average mass. So again the trouble is
determining the volume. I thought about measureing
weight, capacitance, acoustic distance, and flow rate
to keep track of the current volume but I keep coming
back to either the capacitance or pressure. The cap
method would be the easiest I think (aside from using
a pump i guess, but those little buggers are pretty
prices unless someone knows of a cheap one of those)
but i think there would be too great a difference
between drink types ( ie: i dont think a generalized
gin capacitance vs. volume would work) and I think the
overhead for the stamp might be a little much with all
the other things I'm trying to do, so I'm left with
trying pressure????? I hoped to be able to use 1
measurement routine, and just cycle through the
different containers. Either I've made it way harder
than it is, or it is just a very interesting problem I
need to get solved, cheaply if possible [noparse]:)[/noparse]
Any help or comments are greatly appreciated, Thanks
Ross Cooper
A neat little useless fact:
We had the Big Game lottery drawing last night, 2nd
largest in the US to date at $325 Million, any way,
your odds of being killed by lightning =1:~4.3 Million
while the odds of hitting that jackpot=
1:~76.3Million. WOW!!! and 3 people hit it, how about
that!!!
--- "J. Clark Hughes" <jchughes@a...>
wrote:
> Ross:
>
> Not sure what your setup is. If you don't know what
> the fluid is, you won't be
> able to back out the volume because you won't know
> the density (i.e., pressure =
> density * gravity * height). Am I misunderstanding
> your setup?
>
> Clark Hughes
>
> Klutch wrote:
> >
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
__________________________________________________
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
http://taxes.yahoo.com/
(formerly known as junkyards) you should be able to get some MAP
sensors. Manifold Absolute Pressure sensor. They would (naturally) be
effective close to 'standard' atmospheric pressure.
At 11:02 AM -0500 on 4/17/02, Mike DeMetz wrote
>http://sales.goldmine-elec.com/prodinfo.asp?prodid=3888
>You could check at All Electronics, Alltronics, and other surplus dealers.
> > I have been looking around for some cheap pressure
>> sensors(digi key seemed to be the cheapest), anyone
> know of any good cheap ones,
--
.-. .-. .-. .-. .-. .-. .-. .-. .-. .-
\ / \ / \ N / \ C / \ S / \ S / \ M / \ / \ /
`-' `-' `-' `-' `-' `-' `-' `-' `-'
Chuck Britton Education is what is left when
britton@n... you have forgotten everything
North Carolina School of Science & Math you learned in school.
(919) 286-3366 x224 Albert Einstein, 1936
does not seem to be working properly, here goes:
i hope this explins a little better.
overall problem: track volume of several hoppers of
different fluids to accurately pour out ounces.
i am buildig a robotic bartender that makes drinks by
looking up the mix from an EEPROM and then activates
the appropriate solenoid valves to pour out the proper
amounts. I am trying to come up with a way to
properly pour say 1 oz out of each hopper of fluid.
The problem is that the velocity flow rate is
linear(downward slope), not constant. So I need a way
to track how much is in each hopper to open the valve
for the correct amount of time, to properly match the
repective flowrate to volume that changes as the fluid
is poured out. Someone else mentioned that I need the
density, what I planned to do for that was measure
several types of say gin and average them. Anyway, I
examined several ways to measure the volume via
capacitance, weight, etc., but the best way both
functionally and economically, I thought at least, was
to indirectly measure it by finding the pressure from
a custom made manometer. see crude drawing below.
___ _ = sealed top
| | |x| x = pressure sensor -> Stamp
| | | |
|^^^^^| |^| ^ = fluid level
| | | |
| | | |
| | | |
| |__| |
|_ ______|
| |
| |
[noparse][[/noparse]x] [noparse][[/noparse]x]= solenoid valve(gravity feed)
| |
there will be at least 12 of these devices.
I believe that when fluid is placed in the large
hopper , it will flow into the small hopper joined to
it (3" PVC tube and 1" PVC tube) and because the
column of air is trapped in the small tube the
pressure will increase, and therefore I should be able
to fit a curve and get the equation of a line for
pressure vs volume regardless of liquid. If it was a
constant flow I could just use counters for each
hopper and open the valves for some constant time, but
I guess that is the ultimate problem at hand. Maybe I
have made this harder than it really is, ideally a
small pump would work the best, but I am trying to
minimize my costs, as most people do. I was hoping to
get the sensors for a couple 3 bucks maybe, but I
guess I'm dreaming. Anyway, If anyone wants to give
input to my problem, I am more than happy to listen.
And thank you to those that have given input already.
Ross Cooper
--- "Chris Loiacono (E-mail)"
<chris01@t...> wrote:
> Ross:
>
> As far as I have been able to tell, there are no
> inexpensive pressure
> sensors that are designed to tolerate direct contact
> with liquids. Some will
> do quite well when additional silicone grease is
> added to protect their
> internals, however, in a recent exchange with
> Motorola and another sensor
> manufacturer the old method of allowing a column of
> the liquid medium to
> proportionally pressurize dry air above it still
> remains the standard....Of
> course, the nice things about this method are that
> of working with a lower
> pressure range, and with minimal risk of leakage.
>
> Chris
>
>
> > Hello,
> > I have been looking around for some cheap pressure
> > sensors(digi key seemed to be the cheapest),
> anyone
> > know of any good cheap ones, or even a way to
> "roll my
> > own" other than with the "black foam stuff" method
> > from IC chips? This is for a liquid application
> where
> > I have a some manometers built to measure the
> volume
> > indirectly via the pressure. Other methods to get
> the
> > volume(capacitance, weight, etc.)I believe will
> not
> > work as I need to test many different types of
> fluids
> > where I do not know what fluid or how much will be
> > added. The pressure seems to be the only fluid
> > invariant method, unless someone has another idea.
> > Thanks for any help provided,
> > Ross Cooper
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! Tax Center - online filing with TurboTax
> > http://taxes.yahoo.com/
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed.
> Text in the
> > Subject and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
__________________________________________________
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
http://taxes.yahoo.com/
takes the guesswork out of it.
Just my .02
Mark
Original Message
From: Klutch [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=8t8SHy6dtvn0tRzz0QirqXtbdUIw0IVfWO4DA5SyCNl4z8j69aT6_CerjIfKFgBHwyG0JxNHDAdZKg]klutch66@y...[/url
Sent: Wednesday, April 17, 2002 7:45 PM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Cheap Pressure Sensors?
well this will be the 3rd time i try this, my email
does not seem to be working properly, here goes:
i hope this explins a little better.
overall problem: track volume of several hoppers of
different fluids to accurately pour out ounces.
i am buildig a robotic bartender that makes drinks by
looking up the mix from an EEPROM and then activates
the appropriate solenoid valves to pour out the proper
amounts. I am trying to come up with a way to
properly pour say 1 oz out of each hopper of fluid.
The problem is that the velocity flow rate is
linear(downward slope), not constant. So I need a way
to track how much is in each hopper to open the valve
for the correct amount of time, to properly match the
repective flowrate to volume that changes as the fluid
is poured out. Someone else mentioned that I need the
density, what I planned to do for that was measure
several types of say gin and average them. Anyway, I
examined several ways to measure the volume via
capacitance, weight, etc., but the best way both
functionally and economically, I thought at least, was
to indirectly measure it by finding the pressure from
a custom made manometer. see crude drawing below.
___ _ = sealed top
| | |x| x = pressure sensor -> Stamp
| | | |
|^^^^^| |^| ^ = fluid level
| | | |
| | | |
| | | |
| |__| |
|_ ______|
| |
| |
[noparse][[/noparse]x] [noparse][[/noparse]x]= solenoid valve(gravity feed)
| |
there will be at least 12 of these devices.
I believe that when fluid is placed in the large
hopper , it will flow into the small hopper joined to
it (3" PVC tube and 1" PVC tube) and because the
column of air is trapped in the small tube the
pressure will increase, and therefore I should be able
to fit a curve and get the equation of a line for
pressure vs volume regardless of liquid. If it was a
constant flow I could just use counters for each
hopper and open the valves for some constant time, but
I guess that is the ultimate problem at hand. Maybe I
have made this harder than it really is, ideally a
small pump would work the best, but I am trying to
minimize my costs, as most people do. I was hoping to
get the sensors for a couple 3 bucks maybe, but I
guess I'm dreaming. Anyway, If anyone wants to give
input to my problem, I am more than happy to listen.
And thank you to those that have given input already.
Ross Cooper
--- "Chris Loiacono (E-mail)"
<chris01@t...> wrote:
> Ross:
>
> As far as I have been able to tell, there are no
> inexpensive pressure
> sensors that are designed to tolerate direct contact
> with liquids. Some will
> do quite well when additional silicone grease is
> added to protect their
> internals, however, in a recent exchange with
> Motorola and another sensor
> manufacturer the old method of allowing a column of
> the liquid medium to
> proportionally pressurize dry air above it still
> remains the standard....Of
> course, the nice things about this method are that
> of working with a lower
> pressure range, and with minimal risk of leakage.
>
> Chris
>
>
> > Hello,
> > I have been looking around for some cheap pressure
> > sensors(digi key seemed to be the cheapest),
> anyone
> > know of any good cheap ones, or even a way to
> "roll my
> > own" other than with the "black foam stuff" method
> > from IC chips? This is for a liquid application
> where
> > I have a some manometers built to measure the
> volume
> > indirectly via the pressure. Other methods to get
> the
> > volume(capacitance, weight, etc.)I believe will
> not
> > work as I need to test many different types of
> fluids
> > where I do not know what fluid or how much will be
> > added. The pressure seems to be the only fluid
> > invariant method, unless someone has another idea.
> > Thanks for any help provided,
> > Ross Cooper
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! Tax Center - online filing with TurboTax
> > http://taxes.yahoo.com/
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed.
> Text in the
> > Subject and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
__________________________________________________
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
http://taxes.yahoo.com/
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
combinations, you are guaranteed to be 1 of the $325 million winners!
--Dan
Original Message
From: "Klutch" <klutch66@y...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, April 17, 2002 11:09 AM
Subject: Re: [noparse][[/noparse]basicstamps] Cheap Pressure Sensors?
> A neat little useless fact:
> We had the Big Game lottery drawing last night, 2nd
> largest in the US to date at $325 Million, any way,
> your odds of being killed by lightning =1:~4.3 Million
> while the odds of hitting that jackpot=
> 1:~76.3Million. WOW!!! and 3 people hit it, how about
> that!!!
Go to any place which sells lawn mowers and supplies and take a look at the
little bottles of gasoline preservative used to treat the gas in your lawn
mower over winter to keep the politically correct gas from turning to jelly
or separating out into the chemicals which are there to make
environmentalist feel good. Those bottles have a larger reservoir which
contains the supply of additive. There is a secondary container which fill
from the main reservoir when the bottle is squeezed or tilted in some way.
This smaller compartment holds usually about one once of liquid. When you
remove the cap and turn the bottle upside down, only the liquid in the
smaller compartment will run out the neck of the bottle. In your
application, I visualize a hose coming from your large tank of booze filling
both sections of this bottle via gravity when the bottle is in an upright
position. Your machine then turns this bottle upside down to empty the
smaller compartment into your cocktail glass. Note that you may have to
have a solenoid to close and open the cap on the smaller compartment at the
proper time.
Just an idea which popped into my head after reading what you wanted to do.
Henry
Original Message
From: "Klutch" <klutch66@y...>
To: <basicstamps@yahoogroups.com>
Sent: 17 April, 2002 5:44 PM
Subject: RE: [noparse][[/noparse]basicstamps] Cheap Pressure Sensors?
> well this will be the 3rd time i try this, my email
> does not seem to be working properly, here goes:
>
> i hope this explins a little better.
> overall problem: track volume of several hoppers of
> different fluids to accurately pour out ounces.
>
> i am buildig a robotic bartender that makes drinks by
> looking up the mix from an EEPROM and then activates
> the appropriate solenoid valves to pour out the proper
> amounts. I am trying to come up with a way to
> properly pour say 1 oz out of each hopper of fluid.
> The problem is that the velocity flow rate is
> linear(downward slope), not constant. So I need a way
> to track how much is in each hopper to open the valve
> for the correct amount of time, to properly match the
> repective flowrate to volume that changes as the fluid
> is poured out. Someone else mentioned that I need the
> density, what I planned to do for that was measure
> several types of say gin and average them. Anyway, I
> examined several ways to measure the volume via
> capacitance, weight, etc., but the best way both
> functionally and economically, I thought at least, was
> to indirectly measure it by finding the pressure from
> a custom made manometer. see crude drawing below.
> ___ _ = sealed top
> | | |x| x = pressure sensor -> Stamp
> | | | |
> |^^^^^| |^| ^ = fluid level
> | | | |
> | | | |
> | | | |
> | |__| |
> |_ ______|
> | |
> | |
> [noparse][[/noparse]x] [noparse][[/noparse]x]= solenoid valve(gravity feed)
> | |
> there will be at least 12 of these devices.
>
> I believe that when fluid is placed in the large
> hopper , it will flow into the small hopper joined to
> it (3" PVC tube and 1" PVC tube) and because the
> column of air is trapped in the small tube the
> pressure will increase, and therefore I should be able
> to fit a curve and get the equation of a line for
> pressure vs volume regardless of liquid. If it was a
> constant flow I could just use counters for each
> hopper and open the valves for some constant time, but
> I guess that is the ultimate problem at hand. Maybe I
> have made this harder than it really is, ideally a
> small pump would work the best, but I am trying to
> minimize my costs, as most people do. I was hoping to
> get the sensors for a couple 3 bucks maybe, but I
> guess I'm dreaming. Anyway, If anyone wants to give
> input to my problem, I am more than happy to listen.
> And thank you to those that have given input already.
> Ross Cooper
>
>
>
>
>
> --- "Chris Loiacono (E-mail)"
> <chris01@t...> wrote:
> > Ross:
> >
> > As far as I have been able to tell, there are no
> > inexpensive pressure
> > sensors that are designed to tolerate direct contact
> > with liquids. Some will
> > do quite well when additional silicone grease is
> > added to protect their
> > internals, however, in a recent exchange with
> > Motorola and another sensor
> > manufacturer the old method of allowing a column of
> > the liquid medium to
> > proportionally pressurize dry air above it still
> > remains the standard....Of
> > course, the nice things about this method are that
> > of working with a lower
> > pressure range, and with minimal risk of leakage.
> >
> > Chris
> >
> >
> > > Hello,
> > > I have been looking around for some cheap pressure
> > > sensors(digi key seemed to be the cheapest),
> > anyone
> > > know of any good cheap ones, or even a way to
> > "roll my
> > > own" other than with the "black foam stuff" method
> > > from IC chips? This is for a liquid application
> > where
> > > I have a some manometers built to measure the
> > volume
> > > indirectly via the pressure. Other methods to get
> > the
> > > volume(capacitance, weight, etc.)I believe will
> > not
> > > work as I need to test many different types of
> > fluids
> > > where I do not know what fluid or how much will be
> > > added. The pressure seems to be the only fluid
> > > invariant method, unless someone has another idea.
> > > Thanks for any help provided,
> > > Ross Cooper
> > >
> > > __________________________________________________
> > > Do You Yahoo!?
> > > Yahoo! Tax Center - online filing with TurboTax
> > > http://taxes.yahoo.com/
> > >
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> > > Subject and Body of the message will be ignored.
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> >
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can be under the glass ting (like under a table)
Ben
Klutch <klutch66@y...> wrote: I will try to be more specific:
What I am doing is building a robotic bartender.
Making drinks involves simply pouring out predefined
drink formulas(ie: 1 shot vodka, 4 shots orange juice
= screwdriver) via liquid solenoids from 16 seperate
liquid containers. I need to be able to measure maybe
2 gallons per container and be able to pour out with
an accuracy of hopefully some fraction of an ounce,
very doable I think. The velocity flow rate is a dead
linear downward slope according to the basic bernoulli
equation for fluid flow, and some trials I have
performed, but the problem is I cant just use the one
curve and fit a line to it because I have 16 seperate
fluids(at least 16 different potentially unknown
densities). I need to keep track of how much I have
poured out of the container so I know where I am along
the line(ie: 16 counters) , and I believe that this
may be too memory intensive for the stamp to deal
with, along with the other supporting devices (LCD,
EEPROM, Shift Reg. I/O expanders, Keypad, etc.). So
rather than do this, I have built a
manometer/container that I SHOULD, the operative word,
be able to very accurately measure the volume of the
fluid regardless of the fluid type in it from the
pressure. By this method I hope to avoid using all
the counters and memory, and hopefully boil it down to
just 1 measurement routine performed on each
manometer/container seperatley. Anyway, there are
more details, but that is the jist of it, and why I
need the pressure sensors, and why I would like to
minimze cost as this is all currently prototype just
to try to get the bugs and theory worked out. I
havent hashed out the fluid math yet but for a
pressure range, I assume 0<=p<=~20 PSI for the 2
gallons of fluid(assuming 8.33 lb/gal) in a 1"
diameter pipe. If any one has any input, better
method, or something to debunk my method, it would be
greatly appreciated. This originally was supposed to
be a very simple project, but as I dug in it just
spiraled, but that is ok, it has been alot of fun, and
I have learned alot from it. When, and "if", I get it
done, I hope to post it on my website so that others
wont have to stumble and fall quite as much as I have.
Ross Cooper
--- Leroy Hall wrote:
> How much quantity and accuracy do you need? What
> pressure range do you
> need?
> Leroy
>
> Klutch wrote:
> >
> > Hello,
> > I have been looking around for some cheap pressure
> > sensors(digi key seemed to be the cheapest),
> anyone
> > know of any good cheap ones, or even a way to
> "roll my
> > own" other than with the "black foam stuff" method
> > from IC chips? This is for a liquid application
> where
> > I have a some manometers built to measure the
> volume
> > indirectly via the pressure. Other methods to get
> the
> > volume(capacitance, weight, etc.)I believe will
> not
> > work as I need to test many different types of
> fluids
> > where I do not know what fluid or how much will be
> > added. The pressure seems to be the only fluid
> > invariant method, unless someone has another idea.
> > Thanks for any help provided,
> > Ross Cooper
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! Tax Center - online filing with TurboTax
> > http://taxes.yahoo.com/
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
> >
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>
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[noparse][[/noparse]Non-text portions of this message have been removed]
>i am buildig a robotic bartender that makes drinks by
>looking up the mix from an EEPROM and then activates
>the appropriate solenoid valves to pour out the proper
>amounts. I am trying to come up with a way to
>properly pour say 1 oz out of each hopper of fluid.
My suggestion, for what its worth, would be to actually MEASURE 1 fluid
ounce of the liquid, then dispense it. Have you seen how a standard so
called 'automatic jigger'? When you tip the bottle to pour, first it fills
up the jigger, then you can pour it into the glass.
Same sort of idea here. Use 2 solenoids: one before the measuring
container, one after. Assume that the solenoid between the bottle and
measuring container is normally open and the solenoid between the measuring
container and dispense spout is normally closed.
The measuring container holds exactly 1 fluid ounce of liquid and is
normally full. When it is time to dispense the liquid, close the solenoid
between the bottle and measuring container, then open the solenoid between
the measuring container and the spigot. Voila! Exactly 1 fluid ounce of
liquid gets dispensed.
Its a little bit more complicated than this, of course. You have to worry
about vent tubes and such and may want to actually use a little air
pressure to force thick liquids out the spigot. But you can ensure that
exact measures get poured because of the 2 stage nature of the
technique. And it should not take any longer to do this because you allow
the measuring container to fill as soon as you have finished dispensing the
current shot.
dwayne
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
Celebrating 18 years of Engineering Innovation (1984 - 2002)
.-. .-. .-. .-. .-. .-. .-. .-. .-. .-
`-' `-' `-' `-' `-' `-' `-' `-' `-'
Do NOT send unsolicited commercial email to this email address.
This message neither grants consent to receive unsolicited
commercial email nor is intended to solicit commercial email.
vane and a hall effect sensor. then all you do is count pulses.
A periostolic pump would handle the different viscosities of the
various liquids pretty well.
if your application is always the same volume, or can be broken down
into the common units, you might be able to build a pressure pump
like a periostolic. you may have seen the soft rubber tube in the
bathroom soap dispensers at restaurants. each solenoid pulse would
dispense 1 unit. you could break ounces into 10 pulses or some value.
The pump would need to be a pair of check valves, just a rubber flap,
and vaccum tubing that would expand under it's own elasticity to re-
fill after each discharge.
Dave
--- In basicstamps@y..., BENS ANTS <bensrobot@y...> wrote:
>
> For that project, can't you use a pump, much simpler, and the
liquid hoppers can be under the glass ting (like under a table)
> Ben
> Klutch <klutch66@y...> wrote: I will try to be more specific:
> What I am doing is building a robotic bartender.
> Making drinks involves simply pouring out predefined
> drink formulas(ie: 1 shot vodka, 4 shots orange juice
> = screwdriver) via liquid solenoids from 16 seperate
> liquid containers. I need to be able to measure maybe
> 2 gallons per container and be able to pour out with
> an accuracy of hopefully some fraction of an ounce,
> very doable I think. The velocity flow rate is a dead
> linear downward slope according to the basic bernoulli
> equation for fluid flow, and some trials I have
> performed, but the problem is I cant just use the one
> curve and fit a line to it because I have 16 seperate
> fluids(at least 16 different potentially unknown
> densities). I need to keep track of how much I have
> poured out of the container so I know where I am along
> the line(ie: 16 counters) , and I believe that this
> may be too memory intensive for the stamp to deal
> with, along with the other supporting devices (LCD,
> EEPROM, Shift Reg. I/O expanders, Keypad, etc.). So
> rather than do this, I have built a
> manometer/container that I SHOULD, the operative word,
> be able to very accurately measure the volume of the
> fluid regardless of the fluid type in it from the
> pressure. By this method I hope to avoid using all
> the counters and memory, and hopefully boil it down to
> just 1 measurement routine performed on each
> manometer/container seperatley. Anyway, there are
> more details, but that is the jist of it, and why I
> need the pressure sensors, and why I would like to
> minimze cost as this is all currently prototype just
> to try to get the bugs and theory worked out. I
> havent hashed out the fluid math yet but for a
> pressure range, I assume 0<=p<=~20 PSI for the 2
> gallons of fluid(assuming 8.33 lb/gal) in a 1"
> diameter pipe. If any one has any input, better
> method, or something to debunk my method, it would be
> greatly appreciated. This originally was supposed to
> be a very simple project, but as I dug in it just
> spiraled, but that is ok, it has been alot of fun, and
> I have learned alot from it. When, and "if", I get it
> done, I hope to post it on my website so that others
> wont have to stumble and fall quite as much as I have.
> Ross Cooper
>
> --- Leroy Hall wrote:
> > How much quantity and accuracy do you need? What
> > pressure range do you
> > need?
> > Leroy
> >
> > Klutch wrote:
> > >
> > > Hello,
> > > I have been looking around for some cheap pressure
> > > sensors(digi key seemed to be the cheapest),
> > anyone
> > > know of any good cheap ones, or even a way to
> > "roll my
> > > own" other than with the "black foam stuff" method
> > > from IC chips? This is for a liquid application
> > where
> > > I have a some manometers built to measure the
> > volume
> > > indirectly via the pressure. Other methods to get
> > the
> > > volume(capacitance, weight, etc.)I believe will
> > not
> > > work as I need to test many different types of
> > fluids
> > > where I do not know what fluid or how much will be
> > > added. The pressure seems to be the only fluid
> > > invariant method, unless someone has another idea.
> > > Thanks for any help provided,
> > > Ross Cooper
> > >
> > > __________________________________________________
> > > Do You Yahoo!?
> > > Yahoo! Tax Center - online filing with TurboTax
> > > http://taxes.yahoo.com/
> > >
> > > To UNSUBSCRIBE, just send mail to:
> > > basicstamps-unsubscribe@y...
> > > from the same email address that you subscribed.
> > Text in the Subject and Body of the message will be
> > ignored.
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@y...
> > from the same email address that you subscribed.
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> > ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
>
>
> __________________________________________________
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> Yahoo! Tax Center - online filing with TurboTax
> http://taxes.yahoo.com/
>
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> basicstamps-unsubscribe@y...
> from the same email address that you subscribed. Text in the
Subject and Body of the message will be ignored.
>
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http://docs.yahoo.com/info/terms/
>
>
>
>
> BEN (TEAM DBR)
> http://www.geocities.com/temdbr
>
>
>
>
> Do You Yahoo!?
> Get personalised at My Yahoo!.
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
would have a cavity of say, 1/10 ounce and each time it passes the
fill sectin, it fills and as it rotates past the empty section it
pours it into the glass. then you can offer your total volume by
controlling rotations. This is similar to the periostolic pump
method, just a different way of handling the fluid.
btw, does anyone know how they dispense soda at McDonalds ? it
sounds like there is a pump in the machine dispensing known quantites.
Dave
--- In basicstamps@y..., Dwayne Reid <dwayner@p...> wrote:
> At 05:44 PM 4/17/02 -0700, Klutch wrote:
>
> >i am buildig a robotic bartender that makes drinks by
> >looking up the mix from an EEPROM and then activates
> >the appropriate solenoid valves to pour out the proper
> >amounts. I am trying to come up with a way to
> >properly pour say 1 oz out of each hopper of fluid.
>
> My suggestion, for what its worth, would be to actually MEASURE 1
fluid
> ounce of the liquid, then dispense it. Have you seen how a
standard so
> called 'automatic jigger'? When you tip the bottle to pour, first
it fills
> up the jigger, then you can pour it into the glass.
>
> Same sort of idea here. Use 2 solenoids: one before the measuring
> container, one after. Assume that the solenoid between the bottle
and
> measuring container is normally open and the solenoid between the
measuring
> container and dispense spout is normally closed.
>
> The measuring container holds exactly 1 fluid ounce of liquid and
is
> normally full. When it is time to dispense the liquid, close the
solenoid
> between the bottle and measuring container, then open the solenoid
between
> the measuring container and the spigot. Voila! Exactly 1 fluid
ounce of
> liquid gets dispensed.
>
> Its a little bit more complicated than this, of course. You have
to worry
> about vent tubes and such and may want to actually use a little air
> pressure to force thick liquids out the spigot. But you can ensure
that
> exact measures get poured because of the 2 stage nature of the
> technique. And it should not take any longer to do this because
you allow
> the measuring container to fill as soon as you have finished
dispensing the
> current shot.
>
> dwayne
>
>
> Dwayne Reid <dwayner@p...>
> Trinity Electronics Systems Ltd Edmonton, AB, CANADA
> (780) 489-3199 voice (780) 487-6397 fax
>
> Celebrating 18 years of Engineering Innovation (1984 - 2002)
> .-. .-. .-. .-. .-. .-. .-. .-. .-. .-
> `-' `-' `-' `-' `-' `-' `-' `-' `-'
> Do NOT send unsolicited commercial email to this email address.
> This message neither grants consent to receive unsolicited
> commercial email nor is intended to solicit commercial email.
Each cup size is different time.
Original Message
From: "dave_mucha" <davemucha@j...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, May 12, 2002 7:15 AM
Subject: [noparse][[/noparse]basicstamps] Re: Cheap Pressure Sensors?
> yet another method could be a rotating drum in a housing. The drum
> would have a cavity of say, 1/10 ounce and each time it passes the
> fill sectin, it fills and as it rotates past the empty section it
> pours it into the glass. then you can offer your total volume by
> controlling rotations. This is similar to the periostolic pump
> method, just a different way of handling the fluid.
>
> btw, does anyone know how they dispense soda at McDonalds ? it
> sounds like there is a pump in the machine dispensing known quantites.
>
> Dave
>
>
>
>
> --- In basicstamps@y..., Dwayne Reid <dwayner@p...> wrote:
> > At 05:44 PM 4/17/02 -0700, Klutch wrote:
> >
> > >i am buildig a robotic bartender that makes drinks by
> > >looking up the mix from an EEPROM and then activates
> > >the appropriate solenoid valves to pour out the proper
> > >amounts. I am trying to come up with a way to
> > >properly pour say 1 oz out of each hopper of fluid.
> >
> > My suggestion, for what its worth, would be to actually MEASURE 1
> fluid
> > ounce of the liquid, then dispense it. Have you seen how a
> standard so
> > called 'automatic jigger'? When you tip the bottle to pour, first
> it fills
> > up the jigger, then you can pour it into the glass.
> >
> > Same sort of idea here. Use 2 solenoids: one before the measuring
> > container, one after. Assume that the solenoid between the bottle
> and
> > measuring container is normally open and the solenoid between the
> measuring
> > container and dispense spout is normally closed.
> >
> > The measuring container holds exactly 1 fluid ounce of liquid and
> is
> > normally full. When it is time to dispense the liquid, close the
> solenoid
> > between the bottle and measuring container, then open the solenoid
> between
> > the measuring container and the spigot. Voila! Exactly 1 fluid
> ounce of
> > liquid gets dispensed.
> >
> > Its a little bit more complicated than this, of course. You have
> to worry
> > about vent tubes and such and may want to actually use a little air
> > pressure to force thick liquids out the spigot. But you can ensure
> that
> > exact measures get poured because of the 2 stage nature of the
> > technique. And it should not take any longer to do this because
> you allow
> > the measuring container to fill as soon as you have finished
> dispensing the
> > current shot.
> >
> > dwayne
> >
> >
> > Dwayne Reid <dwayner@p...>
> > Trinity Electronics Systems Ltd Edmonton, AB, CANADA
> > (780) 489-3199 voice (780) 487-6397 fax
> >
> > Celebrating 18 years of Engineering Innovation (1984 - 2002)
> > .-. .-. .-. .-. .-. .-. .-. .-. .-. .-
> > `-' `-' `-' `-' `-' `-' `-' `-' `-'
> > Do NOT send unsolicited commercial email to this email address.
> > This message neither grants consent to receive unsolicited
> > commercial email nor is intended to solicit commercial email.
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
contained in large foil bags are mixed with filtered / carbonated tap water
in the nozzle of the drink dispenser. This is why you see clear and colored
fluid coming out of the nozzle.
The pumping you hear is the syrup being sucked from the bag and pumped to
the nozzle. I believe its a constant pressure setup with the quantity being
metered by the nozzle, not a volume measurement.
Dewayne sounds as if he, like me, has been around a bar or two. In places
where they don't trust their employees to measure accurately, they fit a
device on the bottle that dispenses one shot at a time when a lever is
pulled and keeps count of the shots on a mechanical counter. If I remember
right, you pull the lever, invert the bottle, wait for the chamber to fill,
then release the lever, dispensing the booze into the glass.
One suggestion is to visit Home Depot and look at the Homelite brand
two-stroke oil bottle. They have a very unique measurement method for their
small oil bottles. This concept might work well for this application.
Original Message
> yet another method could be a rotating drum in a housing. The drum
> would have a cavity of say, 1/10 ounce and each time it passes the
> fill sectin, it fills and as it rotates past the empty section it
> pours it into the glass. then you can offer your total volume by
> controlling rotations. This is similar to the periostolic pump
> method, just a different way of handling the fluid.
>
> btw, does anyone know how they dispense soda at McDonalds ? it
> sounds like there is a pump in the machine dispensing known quantites.
>
> Dave
>
>
>
>
> --- In basicstamps@y..., Dwayne Reid <dwayner@p...> wrote:
> > At 05:44 PM 4/17/02 -0700, Klutch wrote:
> >
> > >i am buildig a robotic bartender that makes drinks by
> > >looking up the mix from an EEPROM and then activates
> > >the appropriate solenoid valves to pour out the proper
> > >amounts. I am trying to come up with a way to
> > >properly pour say 1 oz out of each hopper of fluid.
> >
> > My suggestion, for what its worth, would be to actually MEASURE 1
> fluid
> > ounce of the liquid, then dispense it. Have you seen how a
> standard so
> > called 'automatic jigger'? When you tip the bottle to pour, first
> it fills
> > up the jigger, then you can pour it into the glass.
> >
> > Same sort of idea here. Use 2 solenoids: one before the measuring
> > container, one after. Assume that the solenoid between the bottle
> and
> > measuring container is normally open and the solenoid between the
> measuring
> > container and dispense spout is normally closed.
> >
> > The measuring container holds exactly 1 fluid ounce of liquid and
> is
> > normally full. When it is time to dispense the liquid, close the
> solenoid
> > between the bottle and measuring container, then open the solenoid
> between
> > the measuring container and the spigot. Voila! Exactly 1 fluid
> ounce of
> > liquid gets dispensed.
> >
> > Its a little bit more complicated than this, of course. You have
> to worry
> > about vent tubes and such and may want to actually use a little air
> > pressure to force thick liquids out the spigot. But you can ensure
> that
> > exact measures get poured because of the 2 stage nature of the
> > technique. And it should not take any longer to do this because
> you allow
> > the measuring container to fill as soon as you have finished
> dispensing the
> > current shot.
the cup and press a button with a certain size icon to fill it? These are
probably time-based, although some have what looks like a spring-loaded
platform to sense the weight. Most have gone to self-service fountains in
the lobby.
Of course the coolest drink machine was the one they had (maybe 15 years
ago -- not there now) at the Burger King on the turnpike rest area near
Wichita, Kansas. The clerk took the order and punched the drinks into a
console. No human handled the cup until it was handed to the customer.
The drink machine dropped the cup, filled it with ice, filled it with drink,
then slid it down to a waiting area where each cup was positioned behind a
two-digit 7-segment display showing what drink was in the cup.
Original Message
> I believe there is only a timer in the dispensing equipment, last I knew.
> Each cup size is different time.
> > yet another method could be a rotating drum in a housing. The drum
> > would have a cavity of say, 1/10 ounce and each time it passes the
> > fill sectin, it fills and as it rotates past the empty section it
> > pours it into the glass. then you can offer your total volume by
> > controlling rotations. This is similar to the periostolic pump
> > method, just a different way of handling the fluid.
> >
> > btw, does anyone know how they dispense soda at McDonalds ? it
> > sounds like there is a pump in the machine dispensing known quantites.
to control the total flow is a workable and simple solution as long
as you can pressureize the liquid.
Since the syrup is in non pressurized bags it only makes sense that
they are using a pump to move the liquid. the style of pump is a key
factor. A perisotolic pump would not require a fixed size nozzle, as
the pump would meter the liquid.
I think we all are going to watch the service guy next time we are in
the store when they are fixing one of those machines.
Now a really neat device would be wireless (rf ?) and send data back
to the cash register.
--- In basicstamps@y..., Rodent <daweasel@s...> wrote:
> The dispensers they use are called post-mix. Concentrated soft-
drink syrup
> contained in large foil bags are mixed with filtered / carbonated
tap water
> in the nozzle of the drink dispenser. This is why you see clear and
colored
> fluid coming out of the nozzle.
>
> The pumping you hear is the syrup being sucked from the bag and
pumped to
> the nozzle. I believe its a constant pressure setup with the
quantity being
> metered by the nozzle, not a volume measurement.
>
> Dewayne sounds as if he, like me, has been around a bar or two. In
places
> where they don't trust their employees to measure accurately, they
fit a
> device on the bottle that dispenses one shot at a time when a lever
is
> pulled and keeps count of the shots on a mechanical counter. If I
remember
> right, you pull the lever, invert the bottle, wait for the chamber
to fill,
> then release the lever, dispensing the booze into the glass.
>
> One suggestion is to visit Home Depot and look at the Homelite brand
> two-stroke oil bottle. They have a very unique measurement method
for their
> small oil bottles. This concept might work well for this
application.
>
>
Original Message
>
>
> > yet another method could be a rotating drum in a housing. The
drum
> > would have a cavity of say, 1/10 ounce and each time it passes the
> > fill sectin, it fills and as it rotates past the empty section it
> > pours it into the glass. then you can offer your total volume by
> > controlling rotations. This is similar to the periostolic pump
> > method, just a different way of handling the fluid.
> >
> > btw, does anyone know how they dispense soda at McDonalds ? it
> > sounds like there is a pump in the machine dispensing known
quantites.
> >
> > Dave
> >
> >
> >
> >
> > --- In basicstamps@y..., Dwayne Reid <dwayner@p...> wrote:
> > > At 05:44 PM 4/17/02 -0700, Klutch wrote:
> > >
> > > >i am buildig a robotic bartender that makes drinks by
> > > >looking up the mix from an EEPROM and then activates
> > > >the appropriate solenoid valves to pour out the proper
> > > >amounts. I am trying to come up with a way to
> > > >properly pour say 1 oz out of each hopper of fluid.
> > >
> > > My suggestion, for what its worth, would be to actually MEASURE
1
> > fluid
> > > ounce of the liquid, then dispense it. Have you seen how a
> > standard so
> > > called 'automatic jigger'? When you tip the bottle to pour,
first
> > it fills
> > > up the jigger, then you can pour it into the glass.
> > >
> > > Same sort of idea here. Use 2 solenoids: one before the
measuring
> > > container, one after. Assume that the solenoid between the
bottle
> > and
> > > measuring container is normally open and the solenoid between
the
> > measuring
> > > container and dispense spout is normally closed.
> > >
> > > The measuring container holds exactly 1 fluid ounce of liquid
and
> > is
> > > normally full. When it is time to dispense the liquid, close
the
> > solenoid
> > > between the bottle and measuring container, then open the
solenoid
> > between
> > > the measuring container and the spigot. Voila! Exactly 1 fluid
> > ounce of
> > > liquid gets dispensed.
> > >
> > > Its a little bit more complicated than this, of course. You
have
> > to worry
> > > about vent tubes and such and may want to actually use a little
air
> > > pressure to force thick liquids out the spigot. But you can
ensure
> > that
> > > exact measures get poured because of the 2 stage nature of the
> > > technique. And it should not take any longer to do this because
> > you allow
> > > the measuring container to fill as soon as you have finished
> > dispensing the
> > > current shot.
I did not realize my questions would generate so much
feedback after my initial postings, anyway in
reference to my original problem I will be using the
Mariotte Siphon that Steve suggested, I built one and
was amazed at the results, and simplification of
programming, and you just can't beat the cost
effectiveness. See below for Steve's old message
(thanks, I owe ya Steve!):
Hi Ross,
I've not been following this thread closely, so
forgive me if this is irrelevant............
designed a system to dispense 500 ml of distilled
water over and over. It was based on a mariotte siphon
The accuracy was very good + - 1 or 2 ml.
I used a timer to control the open time of the valve.
Here's a link to show you how it would work
http://www.uswcl.ars.ag.gov/exper/mariotte.htm
-Steve
Anyway, since you guys are talking about the bars and
stuff monitoring drinks check out the Beverage
Tracker:
www.vitallink.com
The Wall Street Journal had an article maybe 3 weeks
ago on them, they have a full blown RF system that
monitors amounts poured and logs it into a Access
database, check it out, if I was only a little quicker
to the market......
Ross Cooper
--- dave_mucha <davemucha@j...> wrote:
> Constant pressure, known nozzel size and known
> viscosity with timer
> to control the total flow is a workable and simple
> solution as long
> as you can pressureize the liquid.
>
> Since the syrup is in non pressurized bags it only
> makes sense that
> they are using a pump to move the liquid. the style
> of pump is a key
> factor. A perisotolic pump would not require a
> fixed size nozzle, as
> the pump would meter the liquid.
>
> I think we all are going to watch the service guy
> next time we are in
> the store when they are fixing one of those
> machines.
>
> Now a really neat device would be wireless (rf ?)
> and send data back
> to the cash register.
>
>
>
>
>
>
> --- In basicstamps@y..., Rodent <daweasel@s...>
> wrote:
> > The dispensers they use are called post-mix.
> Concentrated soft-
> drink syrup
> > contained in large foil bags are mixed with
> filtered / carbonated
> tap water
> > in the nozzle of the drink dispenser. This is why
> you see clear and
> colored
> > fluid coming out of the nozzle.
> >
> > The pumping you hear is the syrup being sucked
> from the bag and
> pumped to
> > the nozzle. I believe its a constant pressure
> setup with the
> quantity being
> > metered by the nozzle, not a volume measurement.
> >
> > Dewayne sounds as if he, like me, has been around
> a bar or two. In
> places
> > where they don't trust their employees to measure
> accurately, they
> fit a
> > device on the bottle that dispenses one shot at a
> time when a lever
> is
> > pulled and keeps count of the shots on a
> mechanical counter. If I
> remember
> > right, you pull the lever, invert the bottle, wait
> for the chamber
> to fill,
> > then release the lever, dispensing the booze into
> the glass.
> >
> > One suggestion is to visit Home Depot and look at
> the Homelite brand
> > two-stroke oil bottle. They have a very unique
> measurement method
> for their
> > small oil bottles. This concept might work well
> for this
> application.
> >
> >
Original Message
> >
> >
> > > yet another method could be a rotating drum in a
> housing. The
> drum
> > > would have a cavity of say, 1/10 ounce and each
> time it passes the
> > > fill sectin, it fills and as it rotates past the
> empty section it
> > > pours it into the glass. then you can offer
> your total volume by
> > > controlling rotations. This is similar to the
> periostolic pump
> > > method, just a different way of handling the
> fluid.
> > >
> > > btw, does anyone know how they dispense soda at
> McDonalds ? it
> > > sounds like there is a pump in the machine
> dispensing known
> quantites.
> > >
> > > Dave
> > >
> > >
> > >
> > >
> > > --- In basicstamps@y..., Dwayne Reid
> <dwayner@p...> wrote:
> > > > At 05:44 PM 4/17/02 -0700, Klutch wrote:
> > > >
> > > > >i am buildig a robotic bartender that makes
> drinks by
> > > > >looking up the mix from an EEPROM and then
> activates
> > > > >the appropriate solenoid valves to pour out
> the proper
> > > > >amounts. I am trying to come up with a way
> to
> > > > >properly pour say 1 oz out of each hopper of
> fluid.
> > > >
> > > > My suggestion, for what its worth, would be to
> actually MEASURE
> 1
> > > fluid
> > > > ounce of the liquid, then dispense it. Have
> you seen how a
> > > standard so
> > > > called 'automatic jigger'? When you tip the
> bottle to pour,
> first
> > > it fills
> > > > up the jigger, then you can pour it into the
> glass.
> > > >
> > > > Same sort of idea here. Use 2 solenoids: one
> before the
> measuring
> > > > container, one after. Assume that the
> solenoid between the
> bottle
> > > and
> > > > measuring container is normally open and the
> solenoid between
> the
> > > measuring
> > > > container and dispense spout is normally
> closed.
> > > >
> > > > The measuring container holds exactly 1 fluid
> ounce of liquid
> and
> > > is
> > > > normally full. When it is time to dispense
> the liquid, close
> the
> > > solenoid
> > > > between the bottle and measuring container,
> then open the
> solenoid
> > > between
> > > > the measuring container and the spigot.
> Voila! Exactly 1 fluid
> > > ounce of
> > > > liquid gets dispensed.
> > > >
> > > > Its a little bit more complicated than this,
> of course. You
> have
> > > to worry
> > > > about vent tubes and such and may want to
> actually use a little
> air
> > > > pressure to force thick liquids out the
> spigot. But you can
> ensure
> > > that
> > > > exact measures get poured because of the 2
> stage nature of the
> > > > technique. And it should not take any longer
> to do this because
> > > you allow
> > > > the measuring container to fill as soon as you
> have finished
> > > dispensing the
> > > > current shot.
>
>
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