Water Level Sensor..

Archiver

Use air pressure. Basic scuba diving principles. Lets say you wanted to
measure the height of water in a 55gal drum. Take a piece of pvc pipe with
a sealed end cap and stick a barb connector through the top with a piece of
pvc tubing attached. Run this tubing to a Motorola pressure sensor (from
Jameco) and measure the pressure. As the water level falls, the pressure
exerted on the sensor will fall. As the water in the drum rises, the
pressure will rise within the pvc pipe.

Brian

At 03:50 AM 8/29/2003 +0000, you wrote:
<SNIP>

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Archiver

Hey Everyone,

I need to put together a water level display for a friend with a
shallow well, 18' deep to be exact. With very little precipitation this
summer his well is running low and he needs to check the basic water level
prior to taking a shower or filling his horses water tubs etc, to know if
he can do it at the time, or if he needs to wait for the level to rise first.

My question is regarding the level sensor -- he would like to have
feedback regarding the entire well depth. I'd like to use a capacitive
type sensor but don't know if such a critter exists for that length or
within a reasonable price. I've also thought of using an ultrasonic ranger
at the top of the well to get a distance measurement to the water surface,
which I think would work well, but I don't think it would hold up well in
that humid environment. What would you recommend for a basic low
resolution level sensor capable of 18 feet of sensing, that could last for
a while? Tracy, given your experience, what are your thoughts?

Thanks,

Tim


Timothy Medema
CrystaLite, Incorporated
3307 Cedar St. (425) 745-6000 800-666-6065
Everett, WA 98201 Fax: (425) 257-0232

www.crystaliteinc.com
<mailto:timm@c...>timm@c...


The information transmitted is intended only for the person or entity to
whom it is addressed and may contain confidential and/or privileged
material. Any review, retransmission, dissemination or other use of, or
taking of any action in reliance upon, this information by persons or
entities other than the intended recipient is prohibited. If you received
this in error, please contact the sender and delete the material from any
computer.

Archiver

Hi Tim,

My first thought is a pressure sensor.

hermetically sealed, and lowered to depth. water weight is constant
per foot so it should be simple to do.

18 foot is the total depth of the well ? or is the water 18 feet deep
in a 30 foot well ?

If the well is 18 ft deep and he expects 8 ft of water, IIRC, fresh
water is 14.7 pounds for every 34 feet ? (old SCUBA days long past)


How big is the well ? is it a 4" hole, or a 3 ft pit ?

I'm thinking a PVC tube with the coil and a float with another coil
for mass.

And, I assume you already thought that any stuff you put down there
will wind up in the coffee ? ie: use stainless, not copper.

Dave





--- In basicstamps@yahoogroups.com, Timothy Medema <timm@c...> wrote:
>
> Hey Everyone,
>
> I need to put together a water level display for a friend
with a
> shallow well, 18' deep to be exact. With very little precipitation
this
> summer his well is running low and he needs to check the basic
water level
> prior to taking a shower or filling his horses water tubs etc, to
know if
> he can do it at the time, or if he needs to wait for the level to
rise first.
>
> My question is regarding the level sensor -- he would like
to have
> feedback regarding the entire well depth. I'd like to use a
capacitive
> type sensor but don't know if such a critter exists for that length
or
> within a reasonable price. I've also thought of using an
ultrasonic ranger
> at the top of the well to get a distance measurement to the water
surface,
> which I think would work well, but I don't think it would hold up
well in
> that humid environment. What would you recommend for a basic low
> resolution level sensor capable of 18 feet of sensing, that could
last for
> a while? Tracy, given your experience, what are your thoughts?
>
> Thanks,
>
> Tim
>
>
> Timothy Medema
> CrystaLite, Incorporated
> 3307 Cedar St. (425) 745-6000 800-666-6065
> Everett, WA 98201 Fax: (425) 257-0232
>
> www.crystaliteinc.com
> <mailto:timm@c...>timm@c...
>
>
> The information transmitted is intended only for the person or
entity to
> whom it is addressed and may contain confidential and/or privileged
> material. Any review, retransmission, dissemination or other use
of, or
> taking of any action in reliance upon, this information by persons
or
> entities other than the intended recipient is prohibited. If you
received
> this in error, please contact the sender and delete the material
from any
> computer.

Archiver

Hi Dave,

Good ideas. The well is a total of 18' deep and 3' in diameter
for that entire height. Yes, as far as what I put down there ending up in
the coffee -- that's why I like the ultrasonic, sense from the top of the
well, non-contact idea.

Tim

At 03:42 PM 8/28/2003 +0000, you wrote:
>Hi Tim,
>
>My first thought is a pressure sensor.
>
>hermetically sealed, and lowered to depth. water weight is constant
>per foot so it should be simple to do.
>
>18 foot is the total depth of the well ? or is the water 18 feet deep
>in a 30 foot well ?
>
>If the well is 18 ft deep and he expects 8 ft of water, IIRC, fresh
>water is 14.7 pounds for every 34 feet ? (old SCUBA days long past)
>
>
>How big is the well ? is it a 4" hole, or a 3 ft pit ?
>
>I'm thinking a PVC tube with the coil and a float with another coil
>for mass.
>
>And, I assume you already thought that any stuff you put down there
>will wind up in the coffee ? ie: use stainless, not copper.
>
>Dave
>
>
>
>
>
>--- In basicstamps@yahoogroups.com, Timothy Medema <timm@c...> wrote:
> >
> > Hey Everyone,
> >
> > I need to put together a water level display for a friend
>with a
> > shallow well, 18' deep to be exact. With very little precipitation
>this
> > summer his well is running low and he needs to check the basic
>water level
> > prior to taking a shower or filling his horses water tubs etc, to
>know if
> > he can do it at the time, or if he needs to wait for the level to
>rise first.
> >
> > My question is regarding the level sensor -- he would like
>to have
> > feedback regarding the entire well depth. I'd like to use a
>capacitive
> > type sensor but don't know if such a critter exists for that length
>or
> > within a reasonable price. I've also thought of using an
>ultrasonic ranger
> > at the top of the well to get a distance measurement to the water
>surface,
> > which I think would work well, but I don't think it would hold up
>well in
> > that humid environment. What would you recommend for a basic low
> > resolution level sensor capable of 18 feet of sensing, that could
>last for
> > a while? Tracy, given your experience, what are your thoughts?
> >
> > Thanks,
> >
> > Tim
> >
> >
> > Timothy Medema
> > CrystaLite, Incorporated
> > 3307 Cedar St. (425) 745-6000 800-666-6065
> > Everett, WA 98201 Fax: (425) 257-0232
> >
> > www.crystaliteinc.com
> > <mailto:timm@c...>timm@c...
> >
> >
> > The information transmitted is intended only for the person or
>entity to
> > whom it is addressed and may contain confidential and/or privileged
> > material. Any review, retransmission, dissemination or other use
>of, or
> > taking of any action in reliance upon, this information by persons
>or
> > entities other than the intended recipient is prohibited. If you
>received
> > this in error, please contact the sender and delete the material
>from any
> > computer.
>
>
>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/

Archiver

I used a pressure transducer on my ROV that came ready in a water
tight enclosure, with a nice length of wire coming out of it. You
just have to hook up +5V, GND, and then hook the signal wire up to an
analog to digital converter chip and a basic stamp1. See the
rovcircuit.gif in the ROV folder in the file section of this message
board. In the top right corner you'll see the pressure transducer
hooked up to the ADC and the BS1 (you won't need the bob-III chip).
To get this pressure transducer go to digikey.com, the model is:
MSP6025P3-4-ND. It costs $110.50. if you got a long enough cable, you
could just lower the pressure transducer into the well whenever you
needed to test water height. At the top of the well, the cable would
connect to the basic stamp and analog to digital converter (and an
LCD or a laptop to see the output).

--- In basicstamps@yahoogroups.com, Timothy Medema <timm@c...> wrote:
>
> Hi Dave,
>
> Good ideas. The well is a total of 18' deep and 3' in
diameter
> for that entire height. Yes, as far as what I put down there
ending up in
> the coffee -- that's why I like the ultrasonic, sense from the top
of the
> well, non-contact idea.
>
> Tim
>
> At 03:42 PM 8/28/2003 +0000, you wrote:
> >Hi Tim,
> >
> >My first thought is a pressure sensor.
> >
> >hermetically sealed, and lowered to depth. water weight is
constant
> >per foot so it should be simple to do.
> >
> >18 foot is the total depth of the well ? or is the water 18 feet
deep
> >in a 30 foot well ?
> >
> >If the well is 18 ft deep and he expects 8 ft of water, IIRC, fresh
> >water is 14.7 pounds for every 34 feet ? (old SCUBA days long past)
> >
> >
> >How big is the well ? is it a 4" hole, or a 3 ft pit ?
> >
> >I'm thinking a PVC tube with the coil and a float with another coil
> >for mass.
> >
> >And, I assume you already thought that any stuff you put down there
> >will wind up in the coffee ? ie: use stainless, not copper.
> >
> >Dave
> >
> >
> >
> >
> >
> >--- In basicstamps@yahoogroups.com, Timothy Medema <timm@c...>
wrote:
> > >
> > > Hey Everyone,
> > >
> > > I need to put together a water level display for a
friend
> >with a
> > > shallow well, 18' deep to be exact. With very little
precipitation
> >this
> > > summer his well is running low and he needs to check the basic
> >water level
> > > prior to taking a shower or filling his horses water tubs etc,
to
> >know if
> > > he can do it at the time, or if he needs to wait for the level
to
> >rise first.
> > >
> > > My question is regarding the level sensor -- he would
like
> >to have
> > > feedback regarding the entire well depth. I'd like to use a
> >capacitive
> > > type sensor but don't know if such a critter exists for that
length
> >or
> > > within a reasonable price. I've also thought of using an
> >ultrasonic ranger
> > > at the top of the well to get a distance measurement to the
water
> >surface,
> > > which I think would work well, but I don't think it would hold
up
> >well in
> > > that humid environment. What would you recommend for a basic
low
> > > resolution level sensor capable of 18 feet of sensing, that
could
> >last for
> > > a while? Tracy, given your experience, what are your thoughts?
> > >
> > > Thanks,
> > >
> > > Tim
> > >
> > >
> > > Timothy Medema
> > > CrystaLite, Incorporated
> > > 3307 Cedar St. (425) 745-6000 800-666-6065
> > > Everett, WA 98201 Fax: (425) 257-0232
> > >
> > > www.crystaliteinc.com
> > > <mailto:timm@c...>timm@c...
> > >
> > >
> > > The information transmitted is intended only for the person or
> >entity to
> > > whom it is addressed and may contain confidential and/or
privileged
> > > material. Any review, retransmission, dissemination or other
use
> >of, or
> > > taking of any action in reliance upon, this information by
persons
> >or
> > > entities other than the intended recipient is prohibited. If
you
> >received
> > > this in error, please contact the sender and delete the material
> >from any
> > > computer.
> >
> >
> >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/

Archiver

Has anyone ever tried an organ-pipe approach for measuring liquid height in
a tube? As you sweep a sine wave frequency into that type of system with a
small speaker and listen with a microphone, the system will resonate at a
single frequency depending on length of air in the tube. Tune a coke bottle
with water and blow across it to see the effect. I'm guessing that
fractional-inch accuracy would be repeatable if you could resolve to a few
Hertz.

Also, I've not tried it at high frequencies, but at low ones you can measure
the feedback on the exciting speaker itself to determine the resonant
frequency of the system. There will be an impedance spike at the resonant
frequency which is easy to measure via a resistor in series with the driver
speaker. That way a single driver could act as both an exciter-speaker and
sense-microphone. A small/cheap speaker with a coat of varnish on the cone
could be an inexpensive water-proof exciter and sensor at the same time.

If you need some audio math to support such an experiment let me know. I'm
not really a stamp guy, but I do sound for a living.

Mike Sokol
www.modernrecording.com
mikes@m...

---

Original Message

---

From: "Timothy Medema" <timm@c...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, August 28, 2003 11:59 AM
Subject: Re: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..


>
> Hi Dave,
>
> Good ideas. The well is a total of 18' deep and 3' in diameter
> for that entire height. Yes, as far as what I put down there ending up in
> the coffee -- that's why I like the ultrasonic, sense from the top of the
> well, non-contact idea.
>
> Tim
>
> At 03:42 PM 8/28/2003 +0000, you wrote:
> >Hi Tim,
> >
> >My first thought is a pressure sensor.
> >
> >hermetically sealed, and lowered to depth. water weight is constant
> >per foot so it should be simple to do.
> >
> >18 foot is the total depth of the well ? or is the water 18 feet deep
> >in a 30 foot well ?
> >
> >If the well is 18 ft deep and he expects 8 ft of water, IIRC, fresh
> >water is 14.7 pounds for every 34 feet ? (old SCUBA days long past)
> >
> >
> >How big is the well ? is it a 4" hole, or a 3 ft pit ?
> >
> >I'm thinking a PVC tube with the coil and a float with another coil
> >for mass.
> >
> >And, I assume you already thought that any stuff you put down there
> >will wind up in the coffee ? ie: use stainless, not copper.
> >
> >Dave
> >
> >
> >
> >
> >
> >--- In basicstamps@yahoogroups.com, Timothy Medema <timm@c...> wrote:
> > >
> > > Hey Everyone,
> > >
> > > I need to put together a water level display for a friend
> >with a
> > > shallow well, 18' deep to be exact. With very little precipitation
> >this
> > > summer his well is running low and he needs to check the basic
> >water level
> > > prior to taking a shower or filling his horses water tubs etc, to
> >know if
> > > he can do it at the time, or if he needs to wait for the level to
> >rise first.
> > >
> > > My question is regarding the level sensor -- he would like
> >to have
> > > feedback regarding the entire well depth. I'd like to use a
> >capacitive
> > > type sensor but don't know if such a critter exists for that length
> >or
> > > within a reasonable price. I've also thought of using an
> >ultrasonic ranger
> > > at the top of the well to get a distance measurement to the water
> >surface,
> > > which I think would work well, but I don't think it would hold up
> >well in
> > > that humid environment. What would you recommend for a basic low
> > > resolution level sensor capable of 18 feet of sensing, that could
> >last for
> > > a while? Tracy, given your experience, what are your thoughts?
> > >
> > > Thanks,
> > >
> > > Tim
> > >
> > >
> > > Timothy Medema
> > > CrystaLite, Incorporated
> > > 3307 Cedar St. (425) 745-6000 800-666-6065
> > > Everett, WA 98201 Fax: (425) 257-0232
> > >
> > > www.crystaliteinc.com
> > > <mailto:timm@c...>timm@c...
> > >
> > >
> > > The information transmitted is intended only for the person or
> >entity to
> > > whom it is addressed and may contain confidential and/or privileged
> > > material. Any review, retransmission, dissemination or other use
> >of, or
> > > taking of any action in reliance upon, this information by persons
> >or
> > > entities other than the intended recipient is prohibited. If you
> >received
> > > this in error, please contact the sender and delete the material
> >from any
> > > computer.
> >
> >
> >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/
>
>

Archiver

Thanks Sam,

Another great idea, I'm looking into it.

Tim

At 04:11 PM 8/28/2003 +0000, you wrote:
>I used a pressure transducer on my ROV that came ready in a water
>tight enclosure, with a nice length of wire coming out of it. You
>just have to hook up +5V, GND, and then hook the signal wire up to an
>analog to digital converter chip and a basic stamp1. See the
>rovcircuit.gif in the ROV folder in the file section of this message
>board. In the top right corner you'll see the pressure transducer
>hooked up to the ADC and the BS1 (you won't need the bob-III chip).
>To get this pressure transducer go to digikey.com, the model is:
>MSP6025P3-4-ND. It costs $110.50. if you got a long enough cable, you
>could just lower the pressure transducer into the well whenever you
>needed to test water height. At the top of the well, the cable would
>connect to the basic stamp and analog to digital converter (and an
>LCD or a laptop to see the output).
>
>--- In basicstamps@yahoogroups.com, Timothy Medema <timm@c...> wrote:
> >
> > Hi Dave,
> >
> > Good ideas. The well is a total of 18' deep and 3' in
>diameter
> > for that entire height. Yes, as far as what I put down there
>ending up in
> > the coffee -- that's why I like the ultrasonic, sense from the top
>of the
> > well, non-contact idea.
> >
> > Tim
> >
> > At 03:42 PM 8/28/2003 +0000, you wrote:
> > >Hi Tim,
> > >
> > >My first thought is a pressure sensor.
> > >
> > >hermetically sealed, and lowered to depth. water weight is
>constant
> > >per foot so it should be simple to do.
> > >
> > >18 foot is the total depth of the well ? or is the water 18 feet
>deep
> > >in a 30 foot well ?
> > >
> > >If the well is 18 ft deep and he expects 8 ft of water, IIRC, fresh
> > >water is 14.7 pounds for every 34 feet ? (old SCUBA days long past)
> > >
> > >
> > >How big is the well ? is it a 4" hole, or a 3 ft pit ?
> > >
> > >I'm thinking a PVC tube with the coil and a float with another coil
> > >for mass.
> > >
> > >And, I assume you already thought that any stuff you put down there
> > >will wind up in the coffee ? ie: use stainless, not copper.
> > >
> > >Dave
> > >
> > >
> > >
> > >
> > >
> > >--- In basicstamps@yahoogroups.com, Timothy Medema <timm@c...>
>wrote:
> > > >
> > > > Hey Everyone,
> > > >
> > > > I need to put together a water level display for a
>friend
> > >with a
> > > > shallow well, 18' deep to be exact. With very little
>precipitation
> > >this
> > > > summer his well is running low and he needs to check the basic
> > >water level
> > > > prior to taking a shower or filling his horses water tubs etc,
>to
> > >know if
> > > > he can do it at the time, or if he needs to wait for the level
>to
> > >rise first.
> > > >
> > > > My question is regarding the level sensor -- he would
>like
> > >to have
> > > > feedback regarding the entire well depth. I'd like to use a
> > >capacitive
> > > > type sensor but don't know if such a critter exists for that
>length
> > >or
> > > > within a reasonable price. I've also thought of using an
> > >ultrasonic ranger
> > > > at the top of the well to get a distance measurement to the
>water
> > >surface,
> > > > which I think would work well, but I don't think it would hold
>up
> > >well in
> > > > that humid environment. What would you recommend for a basic
>low
> > > > resolution level sensor capable of 18 feet of sensing, that
>could
> > >last for
> > > > a while? Tracy, given your experience, what are your thoughts?
> > > >
> > > > Thanks,
> > > >
> > > > Tim
> > > >
> > > >
> > > > Timothy Medema
> > > > CrystaLite, Incorporated
> > > > 3307 Cedar St. (425) 745-6000 800-666-6065
> > > > Everett, WA 98201 Fax: (425) 257-0232
> > > >
> > > > www.crystaliteinc.com
> > > > <mailto:timm@c...>timm@c...
> > > >
> > > >
> > > > The information transmitted is intended only for the person or
> > >entity to
> > > > whom it is addressed and may contain confidential and/or
>privileged
> > > > material. Any review, retransmission, dissemination or other
>use
> > >of, or
> > > > taking of any action in reliance upon, this information by
>persons
> > >or
> > > > entities other than the intended recipient is prohibited. If
>you
> > >received
> > > > this in error, please contact the sender and delete the material
> > >from any
> > > > computer.
> > >
> > >
> > >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/

Archiver

Hi Tim,

If you only need to know depth at discrete points, there are a lot
more possibilities.. E.g., www.qprox.com has some 2-point level
sensor chips, as well as some that are meant for depth gages.

The longest capacitive sensor I know of commercially is 2 meters
long. I don't know what luck you would have to build one yourself
down to 18 feet (~6 meters). Capacitive sensors are not the most
stable, maybe good to 1%fs accuracy, as deposits left on the sense
wire cause the calibration to drift with time,temperature and
humidity. Especially useless in salt water. I have a lot of
experience with capacitive probes (much of it unpleasant!).

The most accurate water depth sensors are the ones based on a float
and a beaded cable coming up over an encoder wheel to a
counterweight. They can resolve 1 mm in 10s of meters of water
level, better than 0.01% with a stable mounting inside a clean
shelter. That is what the USGS hydrological stations use.

Pressure sensors at the bottom of the well can be good for 1% or
better accuracy. For long term monitoring, it requires a gage
transducer with a vented cable coming up to the top, so you are
measuring the pressure relative to atmospheric. An absolute pressure
transducer is also possible, but then you might have to account for
changes in barometric pressure (150 millibar extreme~5 feet of
water), and temperature. An absolute pressure sensor is fine in
systems where you can lower it down from the surface and get a fix on
pressure both at the surface and at depth within a short time period.
A bubbler system puts the pressure sensor at the top of the well,
instead of at the bottom, and measures the gage pressure necessary to
force gas bubbles out of a tube at a fixed position underwater.

Ultrasound you mention, too, and there are waterproof transducers
available. The electronics is a little more complicated, and the
price of commercial units attests to the nuances of making it work at
its best. But it should work great in an 18' well if there are not a
lot of obstructions.

Mike's idea of a sound probe, to measure the resonant frequency of an
"organ pipe" is fascinating. I've never seen a depth probe based on
that principle. If you've ever listened at the top of a well or a
pipe going down into the water, you know how much the cavity molds
the sounds of water sloshing or other natural sounds.

Another method I've not seen commercially is that of a radio
frequency stub, shorted at the bottom by the water. The quarter-wave
resonance to be monitored and computed to water depth.


-- best regards
Tracy Allen
electronically monitored ecosystems
http://www.emesystems.com
mailto:tracy@e...




>Hey Everyone,
>
> I need to put together a water level display for a friend with a
>shallow well, 18' deep to be exact. With very little precipitation this
>summer his well is running low and he needs to check the basic water level
>prior to taking a shower or filling his horses water tubs etc, to know if
>he can do it at the time, or if he needs to wait for the level to rise first.
>
> My question is regarding the level sensor -- he would like to have
>feedback regarding the entire well depth. I'd like to use a capacitive
>type sensor but don't know if such a critter exists for that length or
>within a reasonable price. I've also thought of using an ultrasonic ranger
>at the top of the well to get a distance measurement to the water surface,
>which I think would work well, but I don't think it would hold up well in
>that humid environment. What would you recommend for a basic low
>resolution level sensor capable of 18 feet of sensing, that could last for
>a while? Tracy, given your experience, what are your thoughts?
>
>Thanks,
>
>Tim
>
>
>Timothy Medema
>CrystaLite, Incorporated
>3307 Cedar St. (425) 745-6000 800-666-6065
>Everett, WA 98201 Fax: (425) 257-0232
>
>www.crystaliteinc.com
><mailto:timm@c...>timm@c...

Archiver

When reading Mike's idea, it stuck me that one could drop a drop of
water and measure the time to impact and the sound of the splash.
(every body has a plan that will not work)


Also, if you considder using a long piece of PVC pipe, you could
insert some sort of sensors and have a magnetic float so that as the
float lifted, it would trip descrete points. that seems to offer the
complete plastic enclosure and simple switches.

just a variation of a theme.

One idea is that you could control a valve(s) so that when the well
went below some points, things like the garden hose would shut off,
or water pressure (and therfore flow) would reduce, allowing the well
to recover or not drain as fast.

That way, you wouldn't be stuck in the shower.

Dave




--- In basicstamps@yahoogroups.com, Tracy Allen <tracy@e...> wrote:
> Hi Tim,
>
> If you only need to know depth at discrete points, there are a lot
> more possibilities.. E.g., www.qprox.com has some 2-point level
> sensor chips, as well as some that are meant for depth gages.
>
> The longest capacitive sensor I know of commercially is 2 meters
> long. I don't know what luck you would have to build one yourself
> down to 18 feet (~6 meters). Capacitive sensors are not the most
> stable, maybe good to 1%fs accuracy, as deposits left on the sense
> wire cause the calibration to drift with time,temperature and
> humidity. Especially useless in salt water. I have a lot of
> experience with capacitive probes (much of it unpleasant!).
>
> The most accurate water depth sensors are the ones based on a float
> and a beaded cable coming up over an encoder wheel to a
> counterweight. They can resolve 1 mm in 10s of meters of water
> level, better than 0.01% with a stable mounting inside a clean
> shelter. That is what the USGS hydrological stations use.
>
> Pressure sensors at the bottom of the well can be good for 1% or
> better accuracy. For long term monitoring, it requires a gage
> transducer with a vented cable coming up to the top, so you are
> measuring the pressure relative to atmospheric. An absolute
pressure
> transducer is also possible, but then you might have to account for
> changes in barometric pressure (150 millibar extreme~5 feet of
> water), and temperature. An absolute pressure sensor is fine in
> systems where you can lower it down from the surface and get a fix
on
> pressure both at the surface and at depth within a short time
period.
> A bubbler system puts the pressure sensor at the top of the well,
> instead of at the bottom, and measures the gage pressure necessary
to
> force gas bubbles out of a tube at a fixed position underwater.
>
> Ultrasound you mention, too, and there are waterproof transducers
> available. The electronics is a little more complicated, and the
> price of commercial units attests to the nuances of making it work
at
> its best. But it should work great in an 18' well if there are not
a
> lot of obstructions.
>
> Mike's idea of a sound probe, to measure the resonant frequency of
an
> "organ pipe" is fascinating. I've never seen a depth probe based
on
> that principle. If you've ever listened at the top of a well or a
> pipe going down into the water, you know how much the cavity molds
> the sounds of water sloshing or other natural sounds.
>
> Another method I've not seen commercially is that of a radio
> frequency stub, shorted at the bottom by the water. The quarter-
wave
> resonance to be monitored and computed to water depth.
>
>
> -- best regards
> Tracy Allen
> electronically monitored ecosystems
> http://www.emesystems.com
> mailto:tracy@e...
>
>
>
>
> >Hey Everyone,
> >
> > I need to put together a water level display for a friend
with a
> >shallow well, 18' deep to be exact. With very little
precipitation this
> >summer his well is running low and he needs to check the basic
water level
> >prior to taking a shower or filling his horses water tubs etc, to
know if
> >he can do it at the time, or if he needs to wait for the level to
rise first.
> >
> > My question is regarding the level sensor -- he would
like to have
> >feedback regarding the entire well depth. I'd like to use a
capacitive
> >type sensor but don't know if such a critter exists for that
length or
> >within a reasonable price. I've also thought of using an
ultrasonic ranger
> >at the top of the well to get a distance measurement to the water
surface,
> >which I think would work well, but I don't think it would hold up
well in
> >that humid environment. What would you recommend for a basic low
> >resolution level sensor capable of 18 feet of sensing, that could
last for
> >a while? Tracy, given your experience, what are your thoughts?
> >
> >Thanks,
> >
> >Tim
> >
> >
> >Timothy Medema
> >CrystaLite, Incorporated
> >3307 Cedar St. (425) 745-6000 800-666-6065
> >Everett, WA 98201 Fax: (425) 257-0232
> >
> >www.crystaliteinc.com
> ><mailto:timm@c...>timm@c...

Archiver

I'm sure the tuned organ-pipe system would work from physics principals, and
the analog processing needed would be quite straightforward. These are
simple extensions of what we audio guys do on a daily basis. The hardware
involved would be inexpensive as well. I really think this could be a great
non-contact way to measure liquid levels, flammable or otherwise. Has anyone
ever seen this method used in a commercial device, or is it a new idea (i.e.
an invention)?

Once the proper analog pre-processing is done, a Stamp could do anything you
wanted to do with the data. Drive a readout, ring a bell, start a pump, etc.
Of course, you could do the whole thing digitally, but I'm not sure a stamp
would have the horsepower for that sort of work. Could be fun to play with
though.

Any feedback?

Mike Sokol
www.modernrecording.com
mikes@m...

---

Original Message

---

From: "Dave Mucha" <davemucha@j...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, August 28, 2003 9:08 PM
Subject: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..


> When reading Mike's idea, it stuck me that one could drop a drop of
> water and measure the time to impact and the sound of the splash.
> (every body has a plan that will not work)
>
>
> Also, if you considder using a long piece of PVC pipe, you could
> insert some sort of sensors and have a magnetic float so that as the
> float lifted, it would trip descrete points. that seems to offer the
> complete plastic enclosure and simple switches.
>
> just a variation of a theme.
>
> One idea is that you could control a valve(s) so that when the well
> went below some points, things like the garden hose would shut off,
> or water pressure (and therfore flow) would reduce, allowing the well
> to recover or not drain as fast.
>
> That way, you wouldn't be stuck in the shower.
>
> Dave
>
>
>
>
> --- In basicstamps@yahoogroups.com, Tracy Allen <tracy@e...> wrote:
> > Hi Tim,
> >
> > If you only need to know depth at discrete points, there are a lot
> > more possibilities.. E.g., www.qprox.com has some 2-point level
> > sensor chips, as well as some that are meant for depth gages.
> >
> > The longest capacitive sensor I know of commercially is 2 meters
> > long. I don't know what luck you would have to build one yourself
> > down to 18 feet (~6 meters). Capacitive sensors are not the most
> > stable, maybe good to 1%fs accuracy, as deposits left on the sense
> > wire cause the calibration to drift with time,temperature and
> > humidity. Especially useless in salt water. I have a lot of
> > experience with capacitive probes (much of it unpleasant!).
> >
> > The most accurate water depth sensors are the ones based on a float
> > and a beaded cable coming up over an encoder wheel to a
> > counterweight. They can resolve 1 mm in 10s of meters of water
> > level, better than 0.01% with a stable mounting inside a clean
> > shelter. That is what the USGS hydrological stations use.
> >
> > Pressure sensors at the bottom of the well can be good for 1% or
> > better accuracy. For long term monitoring, it requires a gage
> > transducer with a vented cable coming up to the top, so you are
> > measuring the pressure relative to atmospheric. An absolute
> pressure
> > transducer is also possible, but then you might have to account for
> > changes in barometric pressure (150 millibar extreme~5 feet of
> > water), and temperature. An absolute pressure sensor is fine in
> > systems where you can lower it down from the surface and get a fix
> on
> > pressure both at the surface and at depth within a short time
> period.
> > A bubbler system puts the pressure sensor at the top of the well,
> > instead of at the bottom, and measures the gage pressure necessary
> to
> > force gas bubbles out of a tube at a fixed position underwater.
> >
> > Ultrasound you mention, too, and there are waterproof transducers
> > available. The electronics is a little more complicated, and the
> > price of commercial units attests to the nuances of making it work
> at
> > its best. But it should work great in an 18' well if there are not
> a
> > lot of obstructions.
> >
> > Mike's idea of a sound probe, to measure the resonant frequency of
> an
> > "organ pipe" is fascinating. I've never seen a depth probe based
> on
> > that principle. If you've ever listened at the top of a well or a
> > pipe going down into the water, you know how much the cavity molds
> > the sounds of water sloshing or other natural sounds.
> >
> > Another method I've not seen commercially is that of a radio
> > frequency stub, shorted at the bottom by the water. The quarter-
> wave
> > resonance to be monitored and computed to water depth.
> >
> >
> > -- best regards
> > Tracy Allen
> > electronically monitored ecosystems
> > http://www.emesystems.com
> > mailto:tracy@e...
> >
> >
> >
> >
> > >Hey Everyone,
> > >
> > > I need to put together a water level display for a friend
> with a
> > >shallow well, 18' deep to be exact. With very little
> precipitation this
> > >summer his well is running low and he needs to check the basic
> water level
> > >prior to taking a shower or filling his horses water tubs etc, to
> know if
> > >he can do it at the time, or if he needs to wait for the level to
> rise first.
> > >
> > > My question is regarding the level sensor -- he would
> like to have
> > >feedback regarding the entire well depth. I'd like to use a
> capacitive
> > >type sensor but don't know if such a critter exists for that
> length or
> > >within a reasonable price. I've also thought of using an
> ultrasonic ranger
> > >at the top of the well to get a distance measurement to the water
> surface,
> > >which I think would work well, but I don't think it would hold up
> well in
> > >that humid environment. What would you recommend for a basic low
> > >resolution level sensor capable of 18 feet of sensing, that could
> last for
> > >a while? Tracy, given your experience, what are your thoughts?
> > >
> > >Thanks,
> > >
> > >Tim
> > >
> > >
> > >Timothy Medema
> > >CrystaLite, Incorporated
> > >3307 Cedar St. (425) 745-6000 800-666-6065
> > >Everett, WA 98201 Fax: (425) 257-0232
> > >
> > >www.crystaliteinc.com
> > ><mailto:timm@c...>timm@c...
>
>
> 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/
>
>

Archiver

I've also thought of using an ultrasonic ranger
> at the top of the well to get a distance measurement to the water
surface,
> which I think would work well, but I don't think it would hold up
well in
> that humid environment.

--what about putting the ultrasonic ranger in an enclosure with a
shutter-like door operated by a solenoid?

Archiver

We talked about ultrasonic on the list a month or two back. Range is limited
but you can extend it by using a tube. Take a look at
http://www.kele.com/olcat/ss6/ALP-V.pdf , its the owner's manual for the
alphasonic units we use to control water level in diatomaceous earth filter
tanks. I don't know anything else about the subject, other than that these
have worked very reliably for a little over five years so far. This is in a
public swimming pool mechanical room - quite hot and very humid 24/7 - also
lots of chloramines in the air - even low grade stainless steel rusts within
a few months there.


>

---

Original Message

---

> From: rdenn25 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=032aax3Sr1qUj4BYoSY22UhxQTe8FMFWMF3_Dhas2DEkqXXMG5OBaAOKizkvLYUidqOhCm-gXw]rad0@a...[/url
> Sent: August 28, 2003 8:51 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..
>
>
> I've also thought of using an ultrasonic ranger
> > at the top of the well to get a distance measurement to the water
> surface,
> > which I think would work well, but I don't think it would hold up
> well in
> > that humid environment.
>
> --what about putting the ultrasonic ranger in an enclosure with a
> shutter-like door operated by a solenoid?
>
>
> 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/
>
>
>

Archiver

I've never seen that idea used in a depth or water level sensor. It
does make sense.

One possible problem is natural noise. In streams at full flow, "the
roar is deafening", and even a narrow measurement tube creates a huge
turbulence wake of its own. I guess that would not usually be a
problem in a well or a tank or a lake. Would extraneous sounds be a
problem? Electronically, the detection system could be made
extremely narrow band.

-- Tracy



>I'm sure the tuned organ-pipe system would work from physics principals, and
>the analog processing needed would be quite straightforward. These are
>simple extensions of what we audio guys do on a daily basis. The hardware
>involved would be inexpensive as well. I really think this could be a great
>non-contact way to measure liquid levels, flammable or otherwise. Has anyone
>ever seen this method used in a commercial device, or is it a new idea (i.e.
>an invention)?
>
>Once the proper analog pre-processing is done, a Stamp could do anything you
>wanted to do with the data. Drive a readout, ring a bell, start a pump, etc.
>Of course, you could do the whole thing digitally, but I'm not sure a stamp
>would have the horsepower for that sort of work. Could be fun to play with
>though.
>
>Any feedback?
>
>Mike Sokol
>www.modernrecording.com
>mikes@m...
>
>
>

---

Original Message

---

>From: "Dave Mucha" <davemucha@j...>
>To: <basicstamps@yahoogroups.com>
>Sent: Thursday, August 28, 2003 9:08 PM
>Subject: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..
>
>
>> When reading Mike's idea, it stuck me that one could drop a drop of
>> water and measure the time to impact and the sound of the splash.
>> (every body has a plan that will not work)
>>
>>
>> Also, if you considder using a long piece of PVC pipe, you could
>> insert some sort of sensors and have a magnetic float so that as the
>> float lifted, it would trip descrete points. that seems to offer the
>> complete plastic enclosure and simple switches.
>>
>> just a variation of a theme.
>>
>> One idea is that you could control a valve(s) so that when the well
>> went below some points, things like the garden hose would shut off,
>> or water pressure (and therfore flow) would reduce, allowing the well
>> to recover or not drain as fast.
>>
>> That way, you wouldn't be stuck in the shower.
>>
>> Dave
>>
>>
>>
>>
>> --- In basicstamps@yahoogroups.com, Tracy Allen <tracy@e...> wrote:
>> > Hi Tim,
>> >
>> > If you only need to know depth at discrete points, there are a lot
>> > more possibilities.. E.g., www.qprox.com has some 2-point level
>> > sensor chips, as well as some that are meant for depth gages.
>> >
>> > The longest capacitive sensor I know of commercially is 2 meters
>> > long. I don't know what luck you would have to build one yourself
>> > down to 18 feet (~6 meters). Capacitive sensors are not the most
> > > stable, maybe good to 1%fs accuracy, as deposits left on the sense
> > > wire cause the calibration to drift with time,temperature and
> > > humidity. Especially useless in salt water. I have a lot of
>> > experience with capacitive probes (much of it unpleasant!).
>> >
>> > The most accurate water depth sensors are the ones based on a float
>> > and a beaded cable coming up over an encoder wheel to a
>> > counterweight. They can resolve 1 mm in 10s of meters of water
> > > level, better than 0.01% with a stable mounting inside a clean
> > > shelter. That is what the USGS hydrological stations use.
> > >
> > > Pressure sensors at the bottom of the well can be good for 1% or
>> > better accuracy. For long term monitoring, it requires a gage
>> > transducer with a vented cable coming up to the top, so you are
>> > measuring the pressure relative to atmospheric. An absolute
>> pressure
>> > transducer is also possible, but then you might have to account for
>> > changes in barometric pressure (150 millibar extreme~5 feet of
>> > water), and temperature. An absolute pressure sensor is fine in
> > > systems where you can lower it down from the surface and get a fix
> > on
>> > pressure both at the surface and at depth within a short time
>> period.
>> > A bubbler system puts the pressure sensor at the top of the well,
>> > instead of at the bottom, and measures the gage pressure necessary
>> to
>> > force gas bubbles out of a tube at a fixed position underwater.
>> >
>> > Ultrasound you mention, too, and there are waterproof transducers
>> > available. The electronics is a little more complicated, and the
>> > price of commercial units attests to the nuances of making it work
>> at
>> > its best. But it should work great in an 18' well if there are not
>> a
>> > lot of obstructions.
>> >
>> > Mike's idea of a sound probe, to measure the resonant frequency of
>> an
>> > "organ pipe" is fascinating. I've never seen a depth probe based
>> on
>> > that principle. If you've ever listened at the top of a well or a
>> > pipe going down into the water, you know how much the cavity molds
>> > the sounds of water sloshing or other natural sounds.
>> >
>> > Another method I've not seen commercially is that of a radio
>> > frequency stub, shorted at the bottom by the water. The quarter-
>> wave
>> > resonance to be monitored and computed to water depth.
>> >
>> >
>> > -- best regards
>> > Tracy Allen
>> > electronically monitored ecosystems
>> > http://www.emesystems.com
>> > mailto:tracy@e...
>> >
>> >
>> >
>> >
>> > >Hey Everyone,
>> > >
>> > > I need to put together a water level display for a friend
>> with a
>> > >shallow well, 18' deep to be exact. With very little
>> precipitation this
>> > >summer his well is running low and he needs to check the basic
>> water level
>> > >prior to taking a shower or filling his horses water tubs etc, to
>> know if
>> > >he can do it at the time, or if he needs to wait for the level to
>> rise first.
>> > >
>> > > My question is regarding the level sensor -- he would
>> like to have
>> > >feedback regarding the entire well depth. I'd like to use a
>> capacitive
>> > >type sensor but don't know if such a critter exists for that
>> length or
>> > >within a reasonable price. I've also thought of using an
>> ultrasonic ranger
>> > >at the top of the well to get a distance measurement to the water
>> surface,
>> > >which I think would work well, but I don't think it would hold up
>> well in
>> > >that humid environment. What would you recommend for a basic low
>> > >resolution level sensor capable of 18 feet of sensing, that could
>> last for
>> > >a while? Tracy, given your experience, what are your thoughts?
>> > >
>> > >Thanks,
>> > >
>> > >Tim
>> > >
>> > >
>> > >Timothy Medema
>> > >CrystaLite, Incorporated
>> > >3307 Cedar St. (425) 745-6000 800-666-6065
>> > >Everett, WA 98201 Fax: (425) 257-0232
>> > >
>> > >www.crystaliteinc.com
>> > ><mailto:timm@c...>timm@c...
>>
>>
>> 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/

Archiver

--- In basicstamps@yahoogroups.com, Brian Gracia <bgracia1@b...>
wrote:
> Use air pressure. Basic scuba diving principles. Lets say you
wanted to
> measure the height of water in a 55gal drum. Take a piece of pvc
pipe with
> a sealed end cap and stick a barb connector through the top with a
piece of
> pvc tubing attached. Run this tubing to a Motorola pressure sensor
(from
> Jameco) and measure the pressure. As the water level falls, the
pressure
> exerted on the sensor will fall. As the water in the drum rises,
the
> pressure will rise within the pvc pipe.
>
> Brian


At first glance, adding air to the bottom of the tank might promore
alge growth? I'm not sure how much oxygen isn in ground water.

If is not only a great idea, it also one that can be very accurate
and is done industrially. So it is proven.

I imagine some form of capacity tank with a couple valves couild be
used.

drain the tank, then seal it, open the water pressure to it and it
will pressureize to the pump pressure. the bubbler will only need
about 8 psi at the 16 ft depth so the pressuers are not hard to
obtain nor hard to measure.

of course, you need to measure the level in the capacity tank and
open and close some valves.

Dave




>
> At 03:50 AM 8/29/2003 +0000, you wrote:
> <SNIP>
>
>

---

>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.512 / Virus Database: 309 - Release Date: 8/19/2003
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

Brian,

I had the same idea, but someone pointed out the the air in the tube would
slowly dissolve into the water. I wonder how much of a "real world" problem
that would be though.

Jonathan

www.madlabs.info

---

Original Message

---

From: "Brian Gracia" <bgracia1@b...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, August 29, 2002 9:44 PM
Subject: Re: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..


> Use air pressure. Basic scuba diving principles. Lets say you wanted to
> measure the height of water in a 55gal drum. Take a piece of pvc pipe
with
> a sealed end cap and stick a barb connector through the top with a piece
of
> pvc tubing attached. Run this tubing to a Motorola pressure sensor (from
> Jameco) and measure the pressure. As the water level falls, the pressure
> exerted on the sensor will fall. As the water in the drum rises, the
> pressure will rise within the pvc pipe.
>
> Brian
>
> At 03:50 AM 8/29/2003 +0000, you wrote:
> <SNIP>
>
>

---

>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.512 / Virus Database: 309 - Release Date: 8/19/2003
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> 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/
>
>
>

Archiver

I think the real problem is water vapor in the air causing problems with the
transducer - these are generally compatible with "clean, dry gases". I've
had problems with long-term drift with these because of that reason.

Jeff

---

Original Message

---

From: "Jonathan Peakall" <jpeakall@m...>


> Brian,
>
> I had the same idea, but someone pointed out the the air in the tube would
> slowly dissolve into the water. I wonder how much of a "real world"
problem
> that would be though.
>
> Jonathan
>
> www.madlabs.info
>
>

---

Original Message

---

> From: "Brian Gracia" <bgracia1@b...>

> > Use air pressure. Basic scuba diving principles. Lets say you wanted
to
> > measure the height of water in a 55gal drum. Take a piece of pvc pipe
> with
> > a sealed end cap and stick a barb connector through the top with a piece
> of
> > pvc tubing attached. Run this tubing to a Motorola pressure sensor
(from
> > Jameco) and measure the pressure. As the water level falls, the
pressure
> > exerted on the sensor will fall. As the water in the drum rises, the
> > pressure will rise within the pvc pipe.
> >
> > Brian

Archiver

The original posted just wanted to know when it was low. While some astonishing
ideas have come across (the organ tube is genus!) We have failed to keep it
simple. he just wants to know when it's close to empty!

A 15 foot pole hanging off the side with a float sensor....when the water drops
to 3 feet or so the float no longer floats...that will close a switch. Cheap,
simple and does what he wants.

My high tech toilet knows when to fill itself by the same technology. [noparse]:)[/noparse]

Tim

>>> kennedy@t... 08/29/03 10:28AM >>>
I think the real problem is water vapor in the air causing problems with the
transducer - these are generally compatible with "clean, dry gases". I've
had problems with long-term drift with these because of that reason.

Jeff

---

Original Message

---

From: "Jonathan Peakall" <jpeakall@m...>


> Brian,
>
> I had the same idea, but someone pointed out the the air in the tube would
> slowly dissolve into the water. I wonder how much of a "real world"
problem
> that would be though.
>
> Jonathan
>
> www.madlabs.info
>
>

---

Original Message

---

> From: "Brian Gracia" <bgracia1@b...>

> > Use air pressure. Basic scuba diving principles. Lets say you wanted
to
> > measure the height of water in a 55gal drum. Take a piece of pvc pipe
> with
> > a sealed end cap and stick a barb connector through the top with a piece
> of
> > pvc tubing attached. Run this tubing to a Motorola pressure sensor
(from
> > Jameco) and measure the pressure. As the water level falls, the
pressure
> > exerted on the sensor will fall. As the water in the drum rises, the
> > pressure will rise within the pvc pipe.
> >
> > Brian



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Archiver

In a message dated 8/29/2003 8:37:40 AM Pacific Daylight Time,
tim.hart@h... writes:
The original posted just wanted to know when it was low. While some
astonishing ideas have come across (the organ tube is genus!) We have failed
to keep
it simple. he just wants to know when it's close to empty!

A 15 foot pole hanging off the side with a float sensor....when the water
drops to 3 feet or so the float no longer floats...that will close a switch.
Cheap, simple and does what he wants.

My high tech toilet knows when to fill itself by the same technology. [noparse]:)[/noparse]

Tim
Great point Tim !!


[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

Tracy,

Go ahead and contact me off-list if this is getting too far off-topic for
this group. But for those interested, here's some thoughts on "organ-pipe"
liquid-level sensors.

One way to overcome the noise problem is to make a tuned narrow-band filter
that follows the sine wave frequency from the signal generator. That way the
sensor only listens to the single frequency in question. You could make this
filter 1 Hz wide if you really wanted to. Doing it digitally would be pretty
straightforward, but a DSP (Digital Sound Processing) chip might be needed
for really fast computations. However, I may be worrying too much about fast
response time, since I'm sure the level change will be quite slow, correct?

Then once the generator sweeps through its range and locks into a "depth"
note, a PLL (phase locked loop) circuit could keep it centered on the
"note". This is how FM radios work to stay on-station. PLL technology is
very refined and affordable. It's just a VCO (Voltage Controlled Oscillator)
and detector. That by it self could form the heart of the exciter/detector
circuit. Then use a stamp (or whatever) to measure the frequency it's locked
on to, process the info for whatever data you want to extract (rate of rise,
absolute depth, etc.) and make something happen. If you need really close
accuracy, you could also calculate the temp of the air in the pipe as well
as barometric pressure and use this data to correct for variations beyond
STP speed of sound (Standard Temperature Pressure) which is 1132 feet per
second at sea level. But I don't think this will be a big number compared to
the change in tube length.

Of course slide-whistles don't have all this excite-filter stuff, and they
do a very good job of following the length of a tube. So do trombones.
Trumpets are the digital version of a 'bone, I guess. In those cases,
there's some sort of general noise excitation of the tuned system, and the
whole system just grabs onto a single note and resonates. Same way with a
laser, albeit at a much higher frequency.


Mike Sokol
www.modernrecording.com
mikes@m...
301-739-6842 voice/fax
301-964-5682 mobile

---

Original Message

---

From: "Tracy Allen" <tracy@e...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, August 29, 2003 2:50 AM
Subject: Re: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..


> I've never seen that idea used in a depth or water level sensor. It
> does make sense.
>
> One possible problem is natural noise. In streams at full flow, "the
> roar is deafening", and even a narrow measurement tube creates a huge
> turbulence wake of its own. I guess that would not usually be a
> problem in a well or a tank or a lake. Would extraneous sounds be a
> problem? Electronically, the detection system could be made
> extremely narrow band.
>
> -- Tracy
>
>
>
> >I'm sure the tuned organ-pipe system would work from physics principals,
and
> >the analog processing needed would be quite straightforward. These are
> >simple extensions of what we audio guys do on a daily basis. The hardware
> >involved would be inexpensive as well. I really think this could be a
great
> >non-contact way to measure liquid levels, flammable or otherwise. Has
anyone
> >ever seen this method used in a commercial device, or is it a new idea
(i.e.
> >an invention)?
> >
> >Once the proper analog pre-processing is done, a Stamp could do anything
you
> >wanted to do with the data. Drive a readout, ring a bell, start a pump,
etc.
> >Of course, you could do the whole thing digitally, but I'm not sure a
stamp
> >would have the horsepower for that sort of work. Could be fun to play
with
> >though.
> >
> >Any feedback?
> >
> >Mike Sokol
> >www.modernrecording.com
> >mikes@m...
> >
> >
> >

---

Original Message

---

> >From: "Dave Mucha" <davemucha@j...>
> >To: <basicstamps@yahoogroups.com>
> >Sent: Thursday, August 28, 2003 9:08 PM
> >Subject: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..
> >
> >
> >> When reading Mike's idea, it stuck me that one could drop a drop of
> >> water and measure the time to impact and the sound of the splash.
> >> (every body has a plan that will not work)
> >>
> >>
> >> Also, if you considder using a long piece of PVC pipe, you could
> >> insert some sort of sensors and have a magnetic float so that as the
> >> float lifted, it would trip descrete points. that seems to offer the
> >> complete plastic enclosure and simple switches.
> >>
> >> just a variation of a theme.
> >>
> >> One idea is that you could control a valve(s) so that when the well
> >> went below some points, things like the garden hose would shut off,
> >> or water pressure (and therfore flow) would reduce, allowing the well
> >> to recover or not drain as fast.
> >>
> >> That way, you wouldn't be stuck in the shower.
> >>
> >> Dave
> >>
> >>
> >>
> >>
> >> --- In basicstamps@yahoogroups.com, Tracy Allen <tracy@e...> wrote:
> >> > Hi Tim,
> >> >
> >> > If you only need to know depth at discrete points, there are a lot
> >> > more possibilities.. E.g., www.qprox.com has some 2-point level
> >> > sensor chips, as well as some that are meant for depth gages.
> >> >
> >> > The longest capacitive sensor I know of commercially is 2 meters
> >> > long. I don't know what luck you would have to build one yourself
> >> > down to 18 feet (~6 meters). Capacitive sensors are not the most
> > > > stable, maybe good to 1%fs accuracy, as deposits left on the sense
> > > > wire cause the calibration to drift with time,temperature and
> > > > humidity. Especially useless in salt water. I have a lot of
> >> > experience with capacitive probes (much of it unpleasant!).
> >> >
> >> > The most accurate water depth sensors are the ones based on a float
> >> > and a beaded cable coming up over an encoder wheel to a
> >> > counterweight. They can resolve 1 mm in 10s of meters of water
> > > > level, better than 0.01% with a stable mounting inside a clean
> > > > shelter. That is what the USGS hydrological stations use.
> > > >
> > > > Pressure sensors at the bottom of the well can be good for 1% or
> >> > better accuracy. For long term monitoring, it requires a gage
> >> > transducer with a vented cable coming up to the top, so you are
> >> > measuring the pressure relative to atmospheric. An absolute
> >> pressure
> >> > transducer is also possible, but then you might have to account for
> >> > changes in barometric pressure (150 millibar extreme~5 feet of
> >> > water), and temperature. An absolute pressure sensor is fine in
> > > > systems where you can lower it down from the surface and get a fix
> > > on
> >> > pressure both at the surface and at depth within a short time
> >> period.
> >> > A bubbler system puts the pressure sensor at the top of the well,
> >> > instead of at the bottom, and measures the gage pressure necessary
> >> to
> >> > force gas bubbles out of a tube at a fixed position underwater.
> >> >
> >> > Ultrasound you mention, too, and there are waterproof transducers
> >> > available. The electronics is a little more complicated, and the
> >> > price of commercial units attests to the nuances of making it work
> >> at
> >> > its best. But it should work great in an 18' well if there are not
> >> a
> >> > lot of obstructions.
> >> >
> >> > Mike's idea of a sound probe, to measure the resonant frequency of
> >> an
> >> > "organ pipe" is fascinating. I've never seen a depth probe based
> >> on
> >> > that principle. If you've ever listened at the top of a well or a
> >> > pipe going down into the water, you know how much the cavity molds
> >> > the sounds of water sloshing or other natural sounds.
> >> >
> >> > Another method I've not seen commercially is that of a radio
> >> > frequency stub, shorted at the bottom by the water. The quarter-
> >> wave
> >> > resonance to be monitored and computed to water depth.
> >> >
> >> >
> >> > -- best regards
> >> > Tracy Allen
> >> > electronically monitored ecosystems
> >> > http://www.emesystems.com
> >> > mailto:tracy@e...
> >> >
> >> >
> >> >
> >> >
> >> > >Hey Everyone,
> >> > >
> >> > > I need to put together a water level display for a friend
> >> with a
> >> > >shallow well, 18' deep to be exact. With very little
> >> precipitation this
> >> > >summer his well is running low and he needs to check the basic
> >> water level
> >> > >prior to taking a shower or filling his horses water tubs etc, to
> >> know if
> >> > >he can do it at the time, or if he needs to wait for the level to
> >> rise first.
> >> > >
> >> > > My question is regarding the level sensor -- he would
> >> like to have
> >> > >feedback regarding the entire well depth. I'd like to use a
> >> capacitive
> >> > >type sensor but don't know if such a critter exists for that
> >> length or
> >> > >within a reasonable price. I've also thought of using an
> >> ultrasonic ranger
> >> > >at the top of the well to get a distance measurement to the water
> >> surface,
> >> > >which I think would work well, but I don't think it would hold up
> >> well in
> >> > >that humid environment. What would you recommend for a basic low
> >> > >resolution level sensor capable of 18 feet of sensing, that could
> >> last for
> >> > >a while? Tracy, given your experience, what are your thoughts?
> >> > >
> >> > >Thanks,
> >> > >
> >> > >Tim
> >> > >
> >> > >
> >> > >Timothy Medema
> >> > >CrystaLite, Incorporated
> >> > >3307 Cedar St. (425) 745-6000 800-666-6065
> >> > >Everett, WA 98201 Fax: (425) 257-0232
> >> > >
> >> > >www.crystaliteinc.com
> >> > ><mailto:timm@c...>timm@c...
> >>
> >>
> >> 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/
>
>
> To UNSUBSCRIBE, just send mail to:
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>
>

Archiver

Ref the organ pipe sensor, of course this is way overkill just to know if a
tank is empty, I was thinking more about a fuel gauge for an airplane where
it would be really good to know that piece of data a bit before that
happened. ; )

Seriously, all sorts of real-world plant applications need to measure liquid
levels, some of which are quite corrosive. The pipe-organ sensor could be a
new technology for that type of engineering challenge.

Please let me know if any of you would like to play with this idea. I don't
have an immediate application for it myself, but could supply the math and
feedback on the design of such a device.

Mike Sokol
www.modernrecording.com
mikes@m...

---

Original Message

---

From: "Tim Hart" <tim.hart@h...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, August 29, 2003 11:36 AM
Subject: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..


> The original posted just wanted to know when it was low. While some
astonishing ideas have come across (the organ tube is genus!) We have
failed to keep it simple. he just wants to know when it's close to empty!
>
> A 15 foot pole hanging off the side with a float sensor....when the water
drops to 3 feet or so the float no longer floats...that will close a switch.
Cheap, simple and does what he wants.
>
> My high tech toilet knows when to fill itself by the same technology. [noparse]:)[/noparse]
>
> Tim
>
> >>> kennedy@t... 08/29/03 10:28AM >>>
> I think the real problem is water vapor in the air causing problems with
the
> transducer - these are generally compatible with "clean, dry gases". I've
> had problems with long-term drift with these because of that reason.
>
> Jeff
>
>

---

Original Message

---

> From: "Jonathan Peakall" <jpeakall@m...>
>
>
> > Brian,
> >
> > I had the same idea, but someone pointed out the the air in the tube
would
> > slowly dissolve into the water. I wonder how much of a "real world"
> problem
> > that would be though.
> >
> > Jonathan
> >
> > www.madlabs.info
> >
> >

---

Original Message

---

> > From: "Brian Gracia" <bgracia1@b...>
>
> > > Use air pressure. Basic scuba diving principles. Lets say you wanted
> to
> > > measure the height of water in a 55gal drum. Take a piece of pvc pipe
> > with
> > > a sealed end cap and stick a barb connector through the top with a
piece
> > of
> > > pvc tubing attached. Run this tubing to a Motorola pressure sensor
> (from
> > > Jameco) and measure the pressure. As the water level falls, the
> pressure
> > > exerted on the sensor will fall. As the water in the drum rises, the
> > > pressure will rise within the pvc pipe.
> > >
> > > Brian
>
>
>
> 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/
>
>

Archiver

One more "stinky" thought. This sort of level sensor would probably work
quite well to measure levels in sewage holding tanks. Mechanical sensors get
crudded up pretty easily. And a glass tube with photo-sensor would quickly
become dirty. But I think the a pipe-organ sensor tube would always know the
depth be able to turn on the pumps.

I love it when different worlds collide.

Mike Sokol
www.modernrecording.com
mikes@m...

---

Original Message

---

From: "Tracy Allen" <tracy@e...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, August 29, 2003 2:50 AM
Subject: Re: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..


> I've never seen that idea used in a depth or water level sensor. It
> does make sense.
>
> One possible problem is natural noise. In streams at full flow, "the
> roar is deafening", and even a narrow measurement tube creates a huge
> turbulence wake of its own. I guess that would not usually be a
> problem in a well or a tank or a lake. Would extraneous sounds be a
> problem? Electronically, the detection system could be made
> extremely narrow band.
>
> -- Tracy
>
>
>
> >I'm sure the tuned organ-pipe system would work from physics principals,
and
> >the analog processing needed would be quite straightforward. These are
> >simple extensions of what we audio guys do on a daily basis. The hardware
> >involved would be inexpensive as well. I really think this could be a
great
> >non-contact way to measure liquid levels, flammable or otherwise. Has
anyone
> >ever seen this method used in a commercial device, or is it a new idea
(i.e.
> >an invention)?
> >
> >Once the proper analog pre-processing is done, a Stamp could do anything
you
> >wanted to do with the data. Drive a readout, ring a bell, start a pump,
etc.
> >Of course, you could do the whole thing digitally, but I'm not sure a
stamp
> >would have the horsepower for that sort of work. Could be fun to play
with
> >though.
> >
> >Any feedback?
> >
> >Mike Sokol
> >www.modernrecording.com
> >mikes@m...
> >
> >
> >

---

Original Message

---

> >From: "Dave Mucha" <davemucha@j...>
> >To: <basicstamps@yahoogroups.com>
> >Sent: Thursday, August 28, 2003 9:08 PM
> >Subject: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..
> >
> >
> >> When reading Mike's idea, it stuck me that one could drop a drop of
> >> water and measure the time to impact and the sound of the splash.
> >> (every body has a plan that will not work)
> >>
> >>
> >> Also, if you considder using a long piece of PVC pipe, you could
> >> insert some sort of sensors and have a magnetic float so that as the
> >> float lifted, it would trip descrete points. that seems to offer the
> >> complete plastic enclosure and simple switches.
> >>
> >> just a variation of a theme.
> >>
> >> One idea is that you could control a valve(s) so that when the well
> >> went below some points, things like the garden hose would shut off,
> >> or water pressure (and therfore flow) would reduce, allowing the well
> >> to recover or not drain as fast.
> >>
> >> That way, you wouldn't be stuck in the shower.
> >>
> >> Dave
> >>
> >>
> >>
> >>
> >> --- In basicstamps@yahoogroups.com, Tracy Allen <tracy@e...> wrote:
> >> > Hi Tim,
> >> >
> >> > If you only need to know depth at discrete points, there are a lot
> >> > more possibilities.. E.g., www.qprox.com has some 2-point level
> >> > sensor chips, as well as some that are meant for depth gages.
> >> >
> >> > The longest capacitive sensor I know of commercially is 2 meters
> >> > long. I don't know what luck you would have to build one yourself
> >> > down to 18 feet (~6 meters). Capacitive sensors are not the most
> > > > stable, maybe good to 1%fs accuracy, as deposits left on the sense
> > > > wire cause the calibration to drift with time,temperature and
> > > > humidity. Especially useless in salt water. I have a lot of
> >> > experience with capacitive probes (much of it unpleasant!).
> >> >
> >> > The most accurate water depth sensors are the ones based on a float
> >> > and a beaded cable coming up over an encoder wheel to a
> >> > counterweight. They can resolve 1 mm in 10s of meters of water
> > > > level, better than 0.01% with a stable mounting inside a clean
> > > > shelter. That is what the USGS hydrological stations use.
> > > >
> > > > Pressure sensors at the bottom of the well can be good for 1% or
> >> > better accuracy. For long term monitoring, it requires a gage
> >> > transducer with a vented cable coming up to the top, so you are
> >> > measuring the pressure relative to atmospheric. An absolute
> >> pressure
> >> > transducer is also possible, but then you might have to account for
> >> > changes in barometric pressure (150 millibar extreme~5 feet of
> >> > water), and temperature. An absolute pressure sensor is fine in
> > > > systems where you can lower it down from the surface and get a fix
> > > on
> >> > pressure both at the surface and at depth within a short time
> >> period.
> >> > A bubbler system puts the pressure sensor at the top of the well,
> >> > instead of at the bottom, and measures the gage pressure necessary
> >> to
> >> > force gas bubbles out of a tube at a fixed position underwater.
> >> >
> >> > Ultrasound you mention, too, and there are waterproof transducers
> >> > available. The electronics is a little more complicated, and the
> >> > price of commercial units attests to the nuances of making it work
> >> at
> >> > its best. But it should work great in an 18' well if there are not
> >> a
> >> > lot of obstructions.
> >> >
> >> > Mike's idea of a sound probe, to measure the resonant frequency of
> >> an
> >> > "organ pipe" is fascinating. I've never seen a depth probe based
> >> on
> >> > that principle. If you've ever listened at the top of a well or a
> >> > pipe going down into the water, you know how much the cavity molds
> >> > the sounds of water sloshing or other natural sounds.
> >> >
> >> > Another method I've not seen commercially is that of a radio
> >> > frequency stub, shorted at the bottom by the water. The quarter-
> >> wave
> >> > resonance to be monitored and computed to water depth.
> >> >
> >> >
> >> > -- best regards
> >> > Tracy Allen
> >> > electronically monitored ecosystems
> >> > http://www.emesystems.com
> >> > mailto:tracy@e...
> >> >
> >> >
> >> >
> >> >
> >> > >Hey Everyone,
> >> > >
> >> > > I need to put together a water level display for a friend
> >> with a
> >> > >shallow well, 18' deep to be exact. With very little
> >> precipitation this
> >> > >summer his well is running low and he needs to check the basic
> >> water level
> >> > >prior to taking a shower or filling his horses water tubs etc, to
> >> know if
> >> > >he can do it at the time, or if he needs to wait for the level to
> >> rise first.
> >> > >
> >> > > My question is regarding the level sensor -- he would
> >> like to have
> >> > >feedback regarding the entire well depth. I'd like to use a
> >> capacitive
> >> > >type sensor but don't know if such a critter exists for that
> >> length or
> >> > >within a reasonable price. I've also thought of using an
> >> ultrasonic ranger
> >> > >at the top of the well to get a distance measurement to the water
> >> surface,
> >> > >which I think would work well, but I don't think it would hold up
> >> well in
> >> > >that humid environment. What would you recommend for a basic low
> >> > >resolution level sensor capable of 18 feet of sensing, that could
> >> last for
> >> > >a while? Tracy, given your experience, what are your thoughts?
> >> > >
> >> > >Thanks,
> >> > >
> >> > >Tim
> >> > >
> >> > >
> >> > >Timothy Medema
> >> > >CrystaLite, Incorporated
> >> > >3307 Cedar St. (425) 745-6000 800-666-6065
> >> > >Everett, WA 98201 Fax: (425) 257-0232
> >> > >
> >> > >www.crystaliteinc.com
> >> > ><mailto:timm@c...>timm@c...
> >>
> >>
> >> 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/
>
>
> 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/
>
>

Archiver

At 08:10 AM 8/30/03 -0400, Mike Sokol - ModernRecording wrote:
>One more "stinky" thought. This sort of level sensor would probably work
>quite well to measure levels in sewage holding tanks. Mechanical sensors get
>crudded up pretty easily. And a glass tube with photo-sensor would quickly
>become dirty. But I think the a pipe-organ sensor tube would always know the
>depth be able to turn on the pumps.
>
>I love it when different worlds collide.
>
>Mike Sokol
>www.modernrecording.com
>mikes@m...

Mike -

In a sewage setup I wonder if one might recirculate and recover the methane
gas to "toot the pipe" so to speak :-)

Bruce Bates




>

---

Original Message

---

>From: "Tracy Allen" <tracy@e...>
>To: <basicstamps@yahoogroups.com>
>Sent: Friday, August 29, 2003 2:50 AM
>Subject: Re: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..
>
>
> > I've never seen that idea used in a depth or water level sensor. It
> > does make sense.
> >
> > One possible problem is natural noise. In streams at full flow, "the
> > roar is deafening", and even a narrow measurement tube creates a huge
> > turbulence wake of its own. I guess that would not usually be a
> > problem in a well or a tank or a lake. Would extraneous sounds be a
> > problem? Electronically, the detection system could be made
> > extremely narrow band.
> >
> > -- Tracy
> >
> >
> >
> > >I'm sure the tuned organ-pipe system would work from physics principals,
>and
> > >the analog processing needed would be quite straightforward. These are
> > >simple extensions of what we audio guys do on a daily basis. The hardware
> > >involved would be inexpensive as well. I really think this could be a
>great
> > >non-contact way to measure liquid levels, flammable or otherwise. Has
>anyone
> > >ever seen this method used in a commercial device, or is it a new idea
>(i.e.
> > >an invention)?
> > >
> > >Once the proper analog pre-processing is done, a Stamp could do anything
>you
> > >wanted to do with the data. Drive a readout, ring a bell, start a pump,
>etc.
> > >Of course, you could do the whole thing digitally, but I'm not sure a
>stamp
> > >would have the horsepower for that sort of work. Could be fun to play
>with
> > >though.
> > >
> > >Any feedback?
> > >
> > >Mike Sokol
> > >www.modernrecording.com
> > >mikes@m...
> > >
> > >
> > >

---

Original Message

---

> > >From: "Dave Mucha" <davemucha@j...>
> > >To: <basicstamps@yahoogroups.com>
> > >Sent: Thursday, August 28, 2003 9:08 PM
> > >Subject: [noparse][[/noparse]basicstamps] Re: Water Level Sensor..
> > >
> > >
> > >> When reading Mike's idea, it stuck me that one could drop a drop of
> > >> water and measure the time to impact and the sound of the splash.
> > >> (every body has a plan that will not work)
> > >>
> > >>
> > >> Also, if you considder using a long piece of PVC pipe, you could
> > >> insert some sort of sensors and have a magnetic float so that as the
> > >> float lifted, it would trip descrete points. that seems to offer the
> > >> complete plastic enclosure and simple switches.
> > >>
> > >> just a variation of a theme.
> > >>
> > >> One idea is that you could control a valve(s) so that when the well
> > >> went below some points, things like the garden hose would shut off,
> > >> or water pressure (and therfore flow) would reduce, allowing the well
> > >> to recover or not drain as fast.
> > >>
> > >> That way, you wouldn't be stuck in the shower.
> > >>
> > >> Dave
> > >>
> > >>
> > >>
> > >>
> > >> --- In basicstamps@yahoogroups.com, Tracy Allen <tracy@e...> wrote:
> > >> > Hi Tim,
> > >> >
> > >> > If you only need to know depth at discrete points, there are a lot
> > >> > more possibilities.. E.g., www.qprox.com has some 2-point level
> > >> > sensor chips, as well as some that are meant for depth gages.
> > >> >
> > >> > The longest capacitive sensor I know of commercially is 2 meters
> > >> > long. I don't know what luck you would have to build one yourself
> > >> > down to 18 feet (~6 meters). Capacitive sensors are not the most
> > > > > stable, maybe good to 1%fs accuracy, as deposits left on the sense
> > > > > wire cause the calibration to drift with time,temperature and
> > > > > humidity. Especially useless in salt water. I have a lot of
> > >> > experience with capacitive probes (much of it unpleasant!).
> > >> >
> > >> > The most accurate water depth sensors are the ones based on a float
> > >> > and a beaded cable coming up over an encoder wheel to a
> > >> > counterweight. They can resolve 1 mm in 10s of meters of water
> > > > > level, better than 0.01% with a stable mounting inside a clean
> > > > > shelter. That is what the USGS hydrological stations use.
> > > > >
> > > > > Pressure sensors at the bottom of the well can be good for 1% or
> > >> > better accuracy. For long term monitoring, it requires a gage
> > >> > transducer with a vented cable coming up to the top, so you are
> > >> > measuring the pressure relative to atmospheric. An absolute
> > >> pressure
> > >> > transducer is also possible, but then you might have to account for
> > >> > changes in barometric pressure (150 millibar extreme~5 feet of
> > >> > water), and temperature. An absolute pressure sensor is fine in
> > > > > systems where you can lower it down from the surface and get a fix
> > > > on
> > >> > pressure both at the surface and at depth within a short time
> > >> period.
> > >> > A bubbler system puts the pressure sensor at the top of the well,
> > >> > instead of at the bottom, and measures the gage pressure necessary
> > >> to
> > >> > force gas bubbles out of a tube at a fixed position underwater.
> > >> >
> > >> > Ultrasound you mention, too, and there are waterproof transducers
> > >> > available. The electronics is a little more complicated, and the
> > >> > price of commercial units attests to the nuances of making it work
> > >> at
> > >> > its best. But it should work great in an 18' well if there are not
> > >> a
> > >> > lot of obstructions.
> > >> >
> > >> > Mike's idea of a sound probe, to measure the resonant frequency of
> > >> an
> > >> > "organ pipe" is fascinating. I've never seen a depth probe based
> > >> on
> > >> > that principle. If you've ever listened at the top of a well or a
> > >> > pipe going down into the water, you know how much the cavity molds
> > >> > the sounds of water sloshing or other natural sounds.
> > >> >
> > >> > Another method I've not seen commercially is that of a radio
> > >> > frequency stub, shorted at the bottom by the water. The quarter-
> > >> wave
> > >> > resonance to be monitored and computed to water depth.
> > >> >
> > >> >
> > >> > -- best regards
> > >> > Tracy Allen
> > >> > electronically monitored ecosystems
> > >> > http://www.emesystems.com
> > >> > mailto:tracy@e...
> > >> >
> > >> >
> > >> >
> > >> >
> > >> > >Hey Everyone,
> > >> > >
> > >> > > I need to put together a water level display for a friend
> > >> with a
> > >> > >shallow well, 18' deep to be exact. With very little
> > >> precipitation this
> > >> > >summer his well is running low and he needs to check the basic
> > >> water level
> > >> > >prior to taking a shower or filling his horses water tubs etc, to
> > >> know if
> > >> > >he can do it at the time, or if he needs to wait for the level to
> > >> rise first.
> > >> > >
> > >> > > My question is regarding the level sensor -- he would
> > >> like to have
> > >> > >feedback regarding the entire well depth. I'd like to use a
> > >> capacitive
> > >> > >type sensor but don't know if such a critter exists for that
> > >> length or
> > >> > >within a reasonable price. I've also thought of using an
> > >> ultrasonic ranger
> > >> > >at the top of the well to get a distance measurement to the water
> > >> surface,
> > >> > >which I think would work well, but I don't think it would hold up
> > >> well in
> > >> > >that humid environment. What would you recommend for a basic low
> > >> > >resolution level sensor capable of 18 feet of sensing, that could
> > >> last for
> > >> > >a while? Tracy, given your experience, what are your thoughts?
> > >> > >
> > >> > >Thanks,
> > >> > >
> > >> > >Tim
> > >> > >
> > >> > >
> > >> > >Timothy Medema
> > >> > >CrystaLite, Incorporated
> > >> > >3307 Cedar St. (425) 745-6000 800-666-6065
> > >> > >Everett, WA 98201 Fax: (425) 257-0232
> > >> > >
> > >> > >www.crystaliteinc.com
> > >> > ><mailto:timm@c...>timm@c...
> > >>
> > >>
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Archiver

Mike,

That well is a pretty large pipe! I think the physics are sound and
maybe practical too but you may be needing a pretty low frequency
speaker - maybe a super subwoofer?

Since you admitted to being a sound guy, what is the resonant
frequency of the well as a pipe? Also what would be the resonant
frequency of a smaller sensing pipe that could be placed into the
well. Maybe a 2" X 18' PVC piece?

Maybe another solution could be a combination of the SONAR approach
but using tone bursts with audible frequencies and outdoor speakers
rather than ultrasonics. At 1.77ms/ft (for dry air! Probably needs
corrected for humidity of the well.) the round trip delay would be
about 32 ms for 18 ft. Some resolution would be lost at the lower
frequencies but to shower or not probably doesn't depend on +-
0.001" of water in the well.

If there is a lot of noise in the well already from a stream or
whatever, maybe the system could "listen" for the frequency with the
largest amplitude? that goes back to the organ pipe idea but using
the white noise from the stream to excite it.

Harry
Stamp Robotics to the next level
www.bluebelldesign.com


--- In basicstamps@yahoogroups.com, "Mike Sokol - ModernRecording"
<mikes@m...> wrote:
> I'm sure the tuned organ-pipe system would work from physics
principals, and
> the analog processing needed would be quite straightforward. These
are
> simple extensions of what we audio guys do on a daily basis. The
hardware
> involved would be inexpensive as well. I really think this could
be a great
> non-contact way to measure liquid levels, flammable or otherwise.
Has anyone
> ever seen this method used in a commercial device, or is it a new
idea (i.e.
> an invention)?
>
<snip...>
> Any feedback?
>
> Mike Sokol
> www.modernrecording.com
> mikes@m...
>
>
>

---

Original Messages cut

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