Designing a low-voltage Moisture Sensor Grid or Pad?

[Ken Moiarty]

[Firstly, my apologies to alt.engineering.electrical if this post is out of
place there.]

Any ideas (and/or recommended references) as to where/how to get started?
What I'm aiming to create is a floor pad, the size of a prototype to be
about four square feet, equipped with densely spaced, evenly distributed
moisture-detection points. Obviously the use here of many moisture
sensitive microchips would get too expensive. So I'm thinking more along
the lines of a grid pattern of wires: wire anodes criss-crossing wire
cathodes, each kept vertically separated by some non-compressible material
possessing excellent water absorbtion characteristics; such that a low
voltage current will flow between anode and cathode (to trigger an
ultrasonic-alarm device) whenever "Kitten decides to do her thing" and the
material thereby becomes wet...
Now, I don't happen to know of any specific materials that would fit this
bill. Nor do I have the specific technical experience or knowledge to
guesstimate whether this idea is even plausible or not.

What I do know I have this problem with 'people and their pets' inside the
house. I have poured over the internet searching for possible technical
solutions to apply to this problem. Some I've purchased and tried (e.g. cat
facial pheromone or Feliway®), but none have worked. I have researched
electronic pet repellants and found a couple of such products that do have a
proven track record. But these simply deter animals from entering or
remaining in a certain area by emitting an ultrasonic noise (silent to
humans) upon the detection of motion --any motion, by any pet, person, or
thing, for any reason. Such a device would definitely scare the cat out of
the house, but wouldn't meet with the cat's owner's approval since it is not
selective for specific problem behavior, and she wants the cat living
indoors. Thus I need to develop a customized (yet affordable) technical
solution, such as would briefly emit an ultrasonic "noise" to startle the
cat, but *only in response to wetting behavior* by the cat.

Therefore, helpful feedback/references/possible plans/schematics/suggestions
appreciated?

TIA,
Ken

 

[Palindr☻me]

[Firstly, my apologies to alt.engineering.electrical if this post is out of
place there.]

Any ideas (and/or recommended references) as to where/how to get started?
What I'm aiming to create is a floor pad, the size of a prototype to be
about four square feet, equipped with densely spaced, evenly distributed
moisture-detection points. Obviously the use here of many moisture
sensitive microchips would get too expensive. So I'm thinking more along
the lines of a grid pattern of wires: wire anodes criss-crossing wire
cathodes, each kept vertically separated by some non-compressible material
possessing excellent water absorbtion characteristics; such that a low
voltage current will flow between anode and cathode (to trigger an
ultrasonic-alarm device) whenever "Kitten decides to do her thing" and the
material thereby becomes wet...
Now, I don't happen to know of any specific materials that would fit this
bill. Nor do I have the specific technical experience or knowledge to
guesstimate whether this idea is even plausible or not.

What I do know I have this problem with 'people and their pets' inside the
house. I have poured over the internet searching for possible technical
solutions to apply to this problem. Some I've purchased and tried (e.g. cat
facial pheromone or Feliway®), but none have worked. I have researched
electronic pet repellants and found a couple of such products that do have a
proven track record. But these simply deter animals from entering or
remaining in a certain area by emitting an ultrasonic noise (silent to
humans) upon the detection of motion --any motion, by any pet, person, or
thing, for any reason. Such a device would definitely scare the cat out of
the house, but wouldn't meet with the cat's owner's approval since it is not
selective for specific problem behavior, and she wants the cat living
indoors. Thus I need to develop a customized (yet affordable) technical
solution, such as would briefly emit an ultrasonic "noise" to startle the
cat, but *only in response to wetting behavior* by the cat.

Therefore, helpful feedback/references/possible plans/schematics/suggestions
appreciated?

You don't need anything that complicated. Just get a suitable non
conductive substrate and use contact adhesive to cover it with a single
sheet of aluminium foil. Then remove small strips of foil to leave an
interlocking pair of spaced fingers. Or form the same sort of thing
using conductive ink. Or use a soft pencil and then electroplate.

Now energise it with a low current alternating voltage between each set
of fingers and sense the impedance. When there is a step change, stick a
couple of thousand volts, very limited current across it - or sound your
ultrasonic "noise". Use ac for sensing to minimise corrosion.

With different settings, it can educate, terminally educate if you wish,
rats,etc. They need quite a large current before they catch fire, btw
and it ruins the fingers.

With yet more different settings, it can play a reward "happy tune",
when fitted to a kiddie's pottie and activated by No 1s or 2s.

Mixing the rat and the child application could be unfortunate..

 

[TimPerry]

[Firstly, my apologies to alt.engineering.electrical if this post is out of
place there.]

Any ideas (and/or recommended references) as to where/how to get started?
What I'm aiming to create is a floor pad, the size of a prototype to be
about four square feet,

one or more stock unetched PC boards. use dremmel or etching tool to cut
traces. Darlington transistor or op-amp to sense conductivity.


equipped with densely spaced, evenly distributed

moisture-detection points.

densely spaced is not needed.

note: urine is hard on electronics. you should seen the mess mice make of
things when they get inside.

maybe trigger a self cleaning spray?

 

[Nelson Johnsrud]

[Firstly, my apologies to alt.engineering.electrical if this post is
out of place there.]

Any ideas (and/or recommended references) as to where/how to get
started? What I'm aiming to create is a floor pad, the size of a
prototype to be about four square feet, equipped with densely spaced,
evenly distributed moisture-detection points. Obviously the use here
of many moisture sensitive microchips would get too expensive. So
I'm thinking more along the lines of a grid pattern of wires: wire
anodes criss-crossing wire cathodes, each kept vertically separated by
some non-compressible material possessing excellent water absorbtion
characteristics; such that a low voltage current will flow between
anode and cathode (to trigger an ultrasonic-alarm device) whenever
"Kitten decides to do her thing" and the material thereby becomes wet...
Now, I don't happen to know of any specific materials that would fit
this bill. Nor do I have the specific technical experience or
knowledge to guesstimate whether this idea is even plausible or not.

What I do know I have this problem with 'people and their pets' inside
the house. I have poured over the internet searching for possible
technical solutions to apply to this problem. Some I've purchased and
tried (e.g. cat facial pheromone or Feliway®), but none have worked.
I have researched electronic pet repellants and found a couple of such
products that do have a proven track record. But these simply deter
animals from entering or remaining in a certain area by emitting an
ultrasonic noise (silent to humans) upon the detection of motion --any
motion, by any pet, person, or thing, for any reason. Such a device
would definitely scare the cat out of the house, but wouldn't meet
with the cat's owner's approval since it is not selective for specific
problem behavior, and she wants the cat living indoors. Thus I need to
develop a customized (yet affordable) technical solution, such as
would briefly emit an ultrasonic "noise" to startle the cat, but *only
in response to wetting behavior* by the cat.

Therefore, helpful feedback/references/possible
plans/schematics/suggestions appreciated?

You don't need anything that complicated. Just get a suitable non
conductive substrate and use contact adhesive to cover it with a single
sheet of aluminium foil. Then remove small strips of foil to leave an
interlocking pair of spaced fingers. Or form the same sort of thing
using conductive ink. Or use a soft pencil and then electroplate.

Now energise it with a low current alternating voltage between each set
of fingers and sense the impedance. When there is a step change, stick a
couple of thousand volts, very limited current across it - or sound your
ultrasonic "noise". Use ac for sensing to minimise corrosion.

With different settings, it can educate, terminally educate if you wish,
rats,etc. They need quite a large current before they catch fire, btw
and it ruins the fingers.

With yet more different settings, it can play a reward "happy tune",
when fitted to a kiddie's pottie and activated by No 1s or 2s.

Mixing the rat and the child application could be unfortunate..

I made something surprisingly similar to this when I was about 11 years
old for mice. A sheet metal square about 12" sq. attached to a piece of
plywood with another smaller (2" sq.) block of wood in the center. Atop
the small block was another smaller metal plate. Each plate was
connected to one side of an ac line cord. This was (in the mind of an
11 year old) the current version of the better mousetrap. Bait was
placed on top the center electrode and I set it up in the barn to watch
the fun. I did have to install a small sacrificial fuse in order to
avoid frying them like bratwurst.

However, to keep it on topic, I modified the same idea a few years ago
to prevent my cat from digging in my rubber plant pot and peeing in the
resulting dirt on the carpet. I placed a wire grid (screen) on the
carpet under the pot, extending about 8" all around it. I put another
grid just below the surface of the dirt in the pot, and hooked each grid
to the poles of a small "electric fencer" circuit I had built. Not
enough to fry the kitty, but definitely enough to keep her from doing it
again. The next time the cat stood on the grid beside the pot with her
hind feet and started digging in the pot with her front paws, she got
the message quickly, and I removed the device.

Nels

 

[DBLEXPOSURE]

[Firstly, my apologies to alt.engineering.electrical if this post is out
of place there.]

Any ideas (and/or recommended references) as to where/how to get started?
What I'm aiming to create is a floor pad, the size of a prototype to be
about four square feet, equipped with densely spaced, evenly distributed
moisture-detection points. Obviously the use here of many moisture
sensitive microchips would get too expensive. So I'm thinking more along
the lines of a grid pattern of wires: wire anodes criss-crossing wire
cathodes, each kept vertically separated by some non-compressible material
possessing excellent water absorbtion characteristics; such that a low
voltage current will flow between anode and cathode (to trigger an
ultrasonic-alarm device) whenever "Kitten decides to do her thing" and the
material thereby becomes wet...
Now, I don't happen to know of any specific materials that would fit this
bill. Nor do I have the specific technical experience or knowledge to
guesstimate whether this idea is even plausible or not.

What I do know I have this problem with 'people and their pets' inside the
house. I have poured over the internet searching for possible technical
solutions to apply to this problem. Some I've purchased and tried (e.g.
cat facial pheromone or Feliway®), but none have worked. I have
researched electronic pet repellants and found a couple of such products
that do have a proven track record. But these simply deter animals from
entering or remaining in a certain area by emitting an ultrasonic noise
(silent to humans) upon the detection of motion --any motion, by any pet,
person, or thing, for any reason. Such a device would definitely scare
the cat out of the house, but wouldn't meet with the cat's owner's
approval since it is not selective for specific problem behavior, and she
wants the cat living indoors. Thus I need to develop a customized (yet
affordable) technical solution, such as would briefly emit an ultrasonic
"noise" to startle the cat, but *only in response to wetting behavior* by
the cat.

Therefore, helpful feedback/references/possible
plans/schematics/suggestions appreciated?

TIA,
Ken

relay switch
| |
E1--0 sensor 0-----------(+) 0---/ ----0
| Op Amp (out) ------relay coil---
---------|------------(-) |
| | Gnd
R1 R2
| |
gnd gnd


A simple Op Amp comparator circuit driving a relay would do it for you.
There needs to be only very little current to get the op amp to go high at
the output. I like the aluminum foil fingers idea that was posted. It is
cheap and easily replaces after the critter soils it.

I don't know what the resistance of cat piss is but it will help you
determine what value resistors are needed.. R1 and R1 should be equal. I
am guess a 12V source and 100Meg resistors to start off with.. Look for a
relay with a high coil resistance, They do make some "reed" relays that
take very little current to fire..

 

[John Fields]

[Firstly, my apologies to alt.engineering.electrical if this post is out
of place there.]

Any ideas (and/or recommended references) as to where/how to get started?
What I'm aiming to create is a floor pad, the size of a prototype to be
about four square feet, equipped with densely spaced, evenly distributed
moisture-detection points. Obviously the use here of many moisture
sensitive microchips would get too expensive. So I'm thinking more along
the lines of a grid pattern of wires: wire anodes criss-crossing wire
cathodes, each kept vertically separated by some non-compressible material
possessing excellent water absorbtion characteristics; such that a low
voltage current will flow between anode and cathode (to trigger an
ultrasonic-alarm device) whenever "Kitten decides to do her thing" and the
material thereby becomes wet...
Now, I don't happen to know of any specific materials that would fit this
bill. Nor do I have the specific technical experience or knowledge to
guesstimate whether this idea is even plausible or not.

What I do know I have this problem with 'people and their pets' inside the
house. I have poured over the internet searching for possible technical
solutions to apply to this problem. Some I've purchased and tried (e.g.
cat facial pheromone or Feliway®), but none have worked. I have
researched electronic pet repellants and found a couple of such products
that do have a proven track record. But these simply deter animals from
entering or remaining in a certain area by emitting an ultrasonic noise
(silent to humans) upon the detection of motion --any motion, by any pet,
person, or thing, for any reason. Such a device would definitely scare
the cat out of the house, but wouldn't meet with the cat's owner's
approval since it is not selective for specific problem behavior, and she
wants the cat living indoors. Thus I need to develop a customized (yet
affordable) technical solution, such as would briefly emit an ultrasonic
"noise" to startle the cat, but *only in response to wetting behavior* by
the cat.

Therefore, helpful feedback/references/possible
plans/schematics/suggestions appreciated?

TIA,
Ken

relay switch
| |
E1--0 sensor 0-----------(+) 0---/ ----0
| Op Amp (out) ------relay coil---
---------|------------(-) |
| | Gnd
R1 R2
| |
gnd gnd


A simple Op Amp comparator circuit driving a relay would do it for you.
There needs to be only very little current to get the op amp to go high at
the output. I like the aluminum foil fingers idea that was posted. It is
cheap and easily replaces after the critter soils it.

I don't know what the resistance of cat piss is but it will help you
determine what value resistors are needed.. R1 and R1 should be equal. I
am guess a 12V source and 100Meg resistors to start off with.. Look for a
relay with a high coil resistance, They do make some "reed" relays that
take very little current to fire..

LOL, you are a troo loon!

Here's what he needs:

+6V>--+----------+---------+--------+-----------+
| | | | |
| | | [10K] |
| | | | |
[SENSOR] | +---|--[1M]--+ |
| | | | | |
| [10K]<--+--|+\ | E
| |POT | >------+--[600R]--B 2N4403
VIN>--+-------------------|-/ LM393 C
| | | | +--------NO
| | | +-----+ |
[100K] | | |K | O--> |<--NC
| | | [DIODE] [COIL]- -|
| | | | | O--COM
GND>--+----------+---------+--------------+-----+

Ground the unused inputs and output of the unused comparator, then
to set it up what you do is to run the pot all the way to ground,
attach the sensor and pee on it, and then adjust the pot until the
relay clicks in and then just a little bit more for good measure.

Then, you take the sensor out wash and dry it and put it back. The
relay can be used to trigger any "disciplinary" device, remembering
that Mark Twain said about cats, "Of all God's creatures, there is
only one that cannot be made the slave of the lash. That one is the
cat. If man could be crossed with a cat it would improve man but it
would deteriorate the cat."

 

[DBLEXPOSURE]

[Firstly, my apologies to alt.engineering.electrical if this post is out
of place there.]

Any ideas (and/or recommended references) as to where/how to get
started?
What I'm aiming to create is a floor pad, the size of a prototype to be
about four square feet, equipped with densely spaced, evenly distributed
moisture-detection points. Obviously the use here of many moisture
sensitive microchips would get too expensive. So I'm thinking more
along
the lines of a grid pattern of wires: wire anodes criss-crossing wire
cathodes, each kept vertically separated by some non-compressible
material
possessing excellent water absorbtion characteristics; such that a low
voltage current will flow between anode and cathode (to trigger an
ultrasonic-alarm device) whenever "Kitten decides to do her thing" and
the
material thereby becomes wet...
Now, I don't happen to know of any specific materials that would fit
this
bill. Nor do I have the specific technical experience or knowledge to
guesstimate whether this idea is even plausible or not.

What I do know I have this problem with 'people and their pets' inside
the
house. I have poured over the internet searching for possible technical
solutions to apply to this problem. Some I've purchased and tried (e.g.
cat facial pheromone or Feliway®), but none have worked. I have
researched electronic pet repellants and found a couple of such products
that do have a proven track record. But these simply deter animals from
entering or remaining in a certain area by emitting an ultrasonic noise
(silent to humans) upon the detection of motion --any motion, by any
pet,
person, or thing, for any reason. Such a device would definitely scare
the cat out of the house, but wouldn't meet with the cat's owner's
approval since it is not selective for specific problem behavior, and
she
wants the cat living indoors. Thus I need to develop a customized (yet
affordable) technical solution, such as would briefly emit an ultrasonic
"noise" to startle the cat, but *only in response to wetting behavior*
by
the cat.

Therefore, helpful feedback/references/possible
plans/schematics/suggestions appreciated?

TIA,
Ken

relay switch
| |
E1--0 sensor 0-----------(+) 0---/ ----0
| Op Amp (out) ------relay coil---
---------|------------(-) |
| | Gnd
R1 R2
| |
gnd gnd


A simple Op Amp comparator circuit driving a relay would do it for you.
There needs to be only very little current to get the op amp to go high at
the output. I like the aluminum foil fingers idea that was posted. It is
cheap and easily replaces after the critter soils it.

I don't know what the resistance of cat piss is but it will help you
determine what value resistors are needed.. R1 and R1 should be equal. I
am guess a 12V source and 100Meg resistors to start off with.. Look for a
relay with a high coil resistance, They do make some "reed" relays that
take very little current to fire..

LOL, you are a troo loon!

Here's what he needs:

+6V>--+----------+---------+--------+-----------+
| | | | |
| | | [10K] |
| | | | |
[SENSOR] | +---|--[1M]--+ |
| | | | | |
| [10K]<--+--|+\ | E
| |POT | >------+--[600R]--B 2N4403
VIN>--+-------------------|-/ LM393 C
| | | | +--------NO
| | | +-----+ |
[100K] | | |K | O--> |<--NC
| | | [DIODE] [COIL]- -|
| | | | | O--COM
GND>--+----------+---------+--------------+-----+

Ground the unused inputs and output of the unused comparator, then
to set it up what you do is to run the pot all the way to ground,
attach the sensor and pee on it, and then adjust the pot until the
relay clicks in and then just a little bit more for good measure.

Then, you take the sensor out wash and dry it and put it back. The
relay can be used to trigger any "disciplinary" device, remembering
that Mark Twain said about cats, "Of all God's creatures, there is
only one that cannot be made the slave of the lash. That one is the
cat. If man could be crossed with a cat it would improve man but it
would deteriorate the cat."

--
John Fields
Professional Circuit Designer

LOL, you are a troo loon!

Lol, Can't argue with that..

But I did build this some years ago,(Not to monitor cat piss). 2 resitors,
op amp and I belive the relay was 5V with a 500ohm coil. Worked fine. Light
goes on, Light goes off.....

But I am sure you will tell my why it dosen't work...

 

[Lumpy]

... What I'm aiming to create is a floor pad,
the size of a prototype to be about four
square feet, equipped with densely
spaced, evenly distributed
moisture-detection points...

Years ago Popular Electronics had a project
for a "Rain Detector". Aluminum foil attached
to a block of wood with rubber cement. Exacto
knife cut through the foil to create two terminals.
Drive it through a simple transistor to whatever
signal device you want.

For a big sensor pad like you want, interlace
several "fingers" of foil contact.


Lump

 

[Palindr☻me]

[Firstly, my apologies to alt.engineering.electrical if this post is out
of place there.]

Any ideas (and/or recommended references) as to where/how to get
started?
What I'm aiming to create is a floor pad, the size of a prototype to be
about four square feet, equipped with densely spaced, evenly distributed
moisture-detection points. Obviously the use here of many moisture
sensitive microchips would get too expensive. So I'm thinking more
along
the lines of a grid pattern of wires: wire anodes criss-crossing wire
cathodes, each kept vertically separated by some non-compressible
material
possessing excellent water absorbtion characteristics; such that a low
voltage current will flow between anode and cathode (to trigger an
ultrasonic-alarm device) whenever "Kitten decides to do her thing" and
the
material thereby becomes wet...
Now, I don't happen to know of any specific materials that would fit
this
bill. Nor do I have the specific technical experience or knowledge to
guesstimate whether this idea is even plausible or not.

What I do know I have this problem with 'people and their pets' inside
the
house. I have poured over the internet searching for possible technical
solutions to apply to this problem. Some I've purchased and tried (e.g.
cat facial pheromone or Feliway®), but none have worked. I have
researched electronic pet repellants and found a couple of such products
that do have a proven track record. But these simply deter animals from
entering or remaining in a certain area by emitting an ultrasonic noise
(silent to humans) upon the detection of motion --any motion, by any
pet,
person, or thing, for any reason. Such a device would definitely scare
the cat out of the house, but wouldn't meet with the cat's owner's
approval since it is not selective for specific problem behavior, and
she
wants the cat living indoors. Thus I need to develop a customized (yet
affordable) technical solution, such as would briefly emit an ultrasonic
"noise" to startle the cat, but *only in response to wetting behavior*
by
the cat.

Therefore, helpful feedback/references/possible
plans/schematics/suggestions appreciated?

TIA,
Ken


relay switch
| |
E1--0 sensor 0-----------(+) 0---/ ----0
| Op Amp (out) ------relay coil---
---------|------------(-) |
| | Gnd
R1 R2
| |
gnd gnd


A simple Op Amp comparator circuit driving a relay would do it for you.
There needs to be only very little current to get the op amp to go high at
the output. I like the aluminum foil fingers idea that was posted. It is
cheap and easily replaces after the critter soils it.

I don't know what the resistance of cat piss is but it will help you
determine what value resistors are needed.. R1 and R1 should be equal. I
am guess a 12V source and 100Meg resistors to start off with.. Look for a
relay with a high coil resistance, They do make some "reed" relays that
take very little current to fire..

LOL, you are a troo loon!

Here's what he needs:

+6V>--+----------+---------+--------+-----------+
| | | | |
| | | [10K] |
| | | | |
[SENSOR] | +---|--[1M]--+ |
| | | | | |
| [10K]<--+--|+\ | E
| |POT | >------+--[600R]--B 2N4403
VIN>--+-------------------|-/ LM393 C
| | | | +--------NO
| | | +-----+ |
[100K] | | |K | O--> |<--NC
| | | [DIODE] [COIL]- -|
| | | | | O--COM
GND>--+----------+---------+--------------+-----+

Ground the unused inputs and output of the unused comparator, then
to set it up what you do is to run the pot all the way to ground,
attach the sensor and pee on it, and then adjust the pot until the
relay clicks in and then just a little bit more for good measure.

Then, you take the sensor out wash and dry it and put it back. The
relay can be used to trigger any "disciplinary" device, remembering
that Mark Twain said about cats, "Of all God's creatures, there is
only one that cannot be made the slave of the lash. That one is the
cat. If man could be crossed with a cat it would improve man but it
would deteriorate the cat."

--
John Fields
Professional Circuit Designer


LOL, you are a troo loon!

Lol, Can't argue with that..

But I did build this some years ago,(Not to monitor cat piss). 2 resitors,
op amp and I belive the relay was 5V with a 500ohm coil. Worked fine. Light
goes on, Light goes off.....

But I am sure you will tell my why it dosen't work...

Personally, I wouldn't use either of them! Sorry about that.

Yours because your comparator is using ground as the
reference. Any "leakage" across the sensor is going to trip
it. The cat stepping on it, or even breathing on it,
probably would. For a non-perfect op amp, it is highly
likely that it will be permanently tripped due to offset
voltage. Because you don't control the back emf from the
relay when it switches off - which could easily zap the op
amp. Because you don't control the maximum voltage between
the inverting and non inverting inputs, which could easily
cause the op amp to permanently lock or self destruct.
Because you use dc across the sensor, which will lead to
corrosion and premature failure. Because you have no
sensitivity or trigger point or hysteresis adjustment. Those
sort of things. Depending on the sensor and the op amp, it
certainly could work - but the odds are that it wouldn't
work reliably in this application..

 

[John Fields]

[Firstly, my apologies to alt.engineering.electrical if this post is out
of place there.]

Any ideas (and/or recommended references) as to where/how to get
started?
What I'm aiming to create is a floor pad, the size of a prototype to be
about four square feet, equipped with densely spaced, evenly distributed
moisture-detection points. Obviously the use here of many moisture
sensitive microchips would get too expensive. So I'm thinking more
along
the lines of a grid pattern of wires: wire anodes criss-crossing wire
cathodes, each kept vertically separated by some non-compressible
material
possessing excellent water absorbtion characteristics; such that a low
voltage current will flow between anode and cathode (to trigger an
ultrasonic-alarm device) whenever "Kitten decides to do her thing" and
the
material thereby becomes wet...
Now, I don't happen to know of any specific materials that would fit
this
bill. Nor do I have the specific technical experience or knowledge to
guesstimate whether this idea is even plausible or not.

What I do know I have this problem with 'people and their pets' inside
the
house. I have poured over the internet searching for possible technical
solutions to apply to this problem. Some I've purchased and tried (e.g.
cat facial pheromone or Feliway®), but none have worked. I have
researched electronic pet repellants and found a couple of such products
that do have a proven track record. But these simply deter animals from
entering or remaining in a certain area by emitting an ultrasonic noise
(silent to humans) upon the detection of motion --any motion, by any
pet,
person, or thing, for any reason. Such a device would definitely scare
the cat out of the house, but wouldn't meet with the cat's owner's
approval since it is not selective for specific problem behavior, and
she
wants the cat living indoors. Thus I need to develop a customized (yet
affordable) technical solution, such as would briefly emit an ultrasonic
"noise" to startle the cat, but *only in response to wetting behavior*
by
the cat.

Therefore, helpful feedback/references/possible
plans/schematics/suggestions appreciated?

TIA,
Ken


relay switch
| |
E1--0 sensor 0-----------(+) 0---/ ----0
| Op Amp (out) ------relay coil---
---------|------------(-) |
| | Gnd
R1 R2
| |
gnd gnd


A simple Op Amp comparator circuit driving a relay would do it for you.
There needs to be only very little current to get the op amp to go high at
the output. I like the aluminum foil fingers idea that was posted. It is
cheap and easily replaces after the critter soils it.

I don't know what the resistance of cat piss is but it will help you
determine what value resistors are needed.. R1 and R1 should be equal. I
am guess a 12V source and 100Meg resistors to start off with.. Look for a
relay with a high coil resistance, They do make some "reed" relays that
take very little current to fire..

LOL, you are a troo loon!

Here's what he needs:

+6V>--+----------+---------+--------+-----------+
| | | | |
| | | [10K] |
| | | | |
[SENSOR] | +---|--[1M]--+ |
| | | | | |
| [10K]<--+--|+\ | E
| |POT | >------+--[600R]--B 2N4403
VIN>--+-------------------|-/ LM393 C
| | | | +--------NO
| | | +-----+ |
[100K] | | |K | O--> |<--NC
| | | [DIODE] [COIL]- -|
| | | | | O--COM
GND>--+----------+---------+--------------+-----+

Ground the unused inputs and output of the unused comparator, then
to set it up what you do is to run the pot all the way to ground,
attach the sensor and pee on it, and then adjust the pot until the
relay clicks in and then just a little bit more for good measure.

Then, you take the sensor out wash and dry it and put it back. The
relay can be used to trigger any "disciplinary" device, remembering
that Mark Twain said about cats, "Of all God's creatures, there is
only one that cannot be made the slave of the lash. That one is the
cat. If man could be crossed with a cat it would improve man but it
would deteriorate the cat."

--
John Fields
Professional Circuit Designer

LOL, you are a troo loon!

Lol, Can't argue with that..

But I did build this some years ago,(Not to monitor cat piss). 2 resitors,
op amp and I belive the relay was 5V with a 500ohm coil. Worked fine. Light
goes on, Light goes off.....

But I am sure you will tell my why it dosen't work...

 

[John Fields]

On Fri, 26 Aug 2005 15:33:19 -0500, "DBLEXPOSURE"



[Firstly, my apologies to alt.engineering.electrical if this post is out
of place there.]

Any ideas (and/or recommended references) as to where/how to get
started?
What I'm aiming to create is a floor pad, the size of a prototype to be
about four square feet, equipped with densely spaced, evenly distributed
moisture-detection points. Obviously the use here of many moisture
sensitive microchips would get too expensive. So I'm thinking more
along
the lines of a grid pattern of wires: wire anodes criss-crossing wire
cathodes, each kept vertically separated by some non-compressible
material
possessing excellent water absorbtion characteristics; such that a low
voltage current will flow between anode and cathode (to trigger an
ultrasonic-alarm device) whenever "Kitten decides to do her thing" and
the
material thereby becomes wet...
Now, I don't happen to know of any specific materials that would fit
this
bill. Nor do I have the specific technical experience or knowledge to
guesstimate whether this idea is even plausible or not.

What I do know I have this problem with 'people and their pets' inside
the
house. I have poured over the internet searching for possible technical
solutions to apply to this problem. Some I've purchased and tried (e.g.
cat facial pheromone or Feliway®), but none have worked. I have
researched electronic pet repellants and found a couple of such products
that do have a proven track record. But these simply deter animals from
entering or remaining in a certain area by emitting an ultrasonic noise
(silent to humans) upon the detection of motion --any motion, by any
pet,
person, or thing, for any reason. Such a device would definitely scare
the cat out of the house, but wouldn't meet with the cat's owner's
approval since it is not selective for specific problem behavior, and
she
wants the cat living indoors. Thus I need to develop a customized (yet
affordable) technical solution, such as would briefly emit an ultrasonic
"noise" to startle the cat, but *only in response to wetting behavior*
by
the cat.

Therefore, helpful feedback/references/possible
plans/schematics/suggestions appreciated?

TIA,
Ken


relay switch
| |
E1--0 sensor 0-----------(+) 0---/ ----0
| Op Amp (out) ------relay coil---
---------|------------(-) |
| | Gnd
R1 R2
| |
gnd gnd


A simple Op Amp comparator circuit driving a relay would do it for you.
There needs to be only very little current to get the op amp to go high at
the output. I like the aluminum foil fingers idea that was posted. It is
cheap and easily replaces after the critter soils it.

I don't know what the resistance of cat piss is but it will help you
determine what value resistors are needed.. R1 and R1 should be equal. I
am guess a 12V source and 100Meg resistors to start off with.. Look for a
relay with a high coil resistance, They do make some "reed" relays that
take very little current to fire..

LOL, you are a troo loon!

Here's what he needs:

+6V>--+----------+---------+--------+-----------+
| | | | |
| | | [10K] |
| | | | |
[SENSOR] | +---|--[1M]--+ |
| | | | | |
| [10K]<--+--|+\ | E
| |POT | >------+--[600R]--B 2N4403
VIN>--+-------------------|-/ LM393 C
| | | | +--------NO
| | | +-----+ |
[100K] | | |K | O--> |<--NC
| | | [DIODE] [COIL]- -|
| | | | | O--COM
GND>--+----------+---------+--------------+-----+

Ground the unused inputs and output of the unused comparator, then
to set it up what you do is to run the pot all the way to ground,
attach the sensor and pee on it, and then adjust the pot until the
relay clicks in and then just a little bit more for good measure.

Then, you take the sensor out wash and dry it and put it back. The
relay can be used to trigger any "disciplinary" device, remembering
that Mark Twain said about cats, "Of all God's creatures, there is
only one that cannot be made the slave of the lash. That one is the
cat. If man could be crossed with a cat it would improve man but it
would deteriorate the cat."

--
John Fields
Professional Circuit Designer


LOL, you are a troo loon!

Lol, Can't argue with that..

But I did build this some years ago,(Not to monitor cat piss). 2 resitors,
op amp and I belive the relay was 5V with a 500ohm coil. Worked fine. Light
goes on, Light goes off.....

But I am sure you will tell my why it dosen't work...

Personally, I wouldn't use either of them! Sorry about that.

Yours because your comparator is using ground as the
reference. Any "leakage" across the sensor is going to trip
it. The cat stepping on it, or even breathing on it,
probably would. For a non-perfect op amp, it is highly
likely that it will be permanently tripped due to offset
voltage. Because you don't control the back emf from the
relay when it switches off - which could easily zap the op
amp. Because you don't control the maximum voltage between
the inverting and non inverting inputs, which could easily
cause the op amp to permanently lock or self destruct.
Because you use dc across the sensor, which will lead to
corrosion and premature failure. Because you have no
sensitivity or trigger point or hysteresis adjustment. Those
sort of things. Depending on the sensor and the op amp, it
certainly could work - but the odds are that it wouldn't
work reliably in this application..

 

[Palindr☻me]

Oh, every engineer has their own way of doing things, have their
favourite chips and favourite building blocks.

I am quite possibly too hung up on always using ac with liquid sensors.
I thought that your circuit, even with the current limited to microamps,
would tend to encourage dendritic growth or electrochemical migration -
particularly with the odd chemicals that might crystalise out of cat
urine in place. It depends on the gap left between the fingers and the
underlying substrate, of course. But you do have 6 volts across the gaps.

I may easily be wrong! I tend to be very lazy and stick to the building
blocks I have used before..

 

[quietguy]

Had you thought of buying or hiring the bell and pad system used for kids that
wet their bed?

David

 

[John Fields]

Oh, every engineer has their own way of doing things, have their
favourite chips and favourite building blocks.

I am quite possibly too hung up on always using ac with liquid sensors.
I thought that your circuit, even with the current limited to microamps,
would tend to encourage dendritic growth or electrochemical migration -
particularly with the odd chemicals that might crystalise out of cat
urine in place. It depends on the gap left between the fingers and the
underlying substrate, of course. But you do have 6 volts across the gaps.

I may easily be wrong! I tend to be very lazy and stick to the building
blocks I have used before..

---
For this application, I tend to think of the sensor as something
like a couple of pieces of conductive window screen with a paper
towel between them and paper towels on their outsides, so I don't
think there'd be a lot of time for much to happen, chemically, after
the cat peed on the affair. Especially since, if it works, (that
is, if whatever happens to the cat as a deterrent to keep it from
peeing there again works) it'll probably only be used once or twice
and I suspect the paper towels would be replaced between uses.

 

[Palindr☻me]

---
For this application, I tend to think of the sensor as something
like a couple of pieces of conductive window screen with a paper
towel between them and paper towels on their outsides, so I don't
think there'd be a lot of time for much to happen, chemically, after
the cat peed on the affair. Especially since, if it works, (that
is, if whatever happens to the cat as a deterrent to keep it from
peeing there again works) it'll probably only be used once or twice
and I suspect the paper towels would be replaced between uses.

I hadn't thought of using a layer of paper towel. Sounds a good idea as
the liquid has to go somewhere...Better to have an instant mop. As you
say, it will hopefully only be used a couple of times and is not the
sort of thing that you would want to keep around afterwards as a
conversation piece.

I assume that kittens do actually know when they are weeing? We may only
be training it to avoid walking on paper towels/shiny metal surfaces.
IIRC, several AI systems have failed due to the wrong choice of training
sets..

 

[DBLEXPOSURE]

On Fri, 26 Aug 2005 15:33:19 -0500, "DBLEXPOSURE"



[Firstly, my apologies to alt.engineering.electrical if this post is
out
of place there.]

Any ideas (and/or recommended references) as to where/how to get
started?
What I'm aiming to create is a floor pad, the size of a prototype to
be
about four square feet, equipped with densely spaced, evenly
distributed
moisture-detection points. Obviously the use here of many moisture
sensitive microchips would get too expensive. So I'm thinking more
along
the lines of a grid pattern of wires: wire anodes criss-crossing wire
cathodes, each kept vertically separated by some non-compressible
material
possessing excellent water absorbtion characteristics; such that a low
voltage current will flow between anode and cathode (to trigger an
ultrasonic-alarm device) whenever "Kitten decides to do her thing" and
the
material thereby becomes wet...
Now, I don't happen to know of any specific materials that would fit
this
bill. Nor do I have the specific technical experience or knowledge to
guesstimate whether this idea is even plausible or not.

What I do know I have this problem with 'people and their pets' inside
the
house. I have poured over the internet searching for possible
technical
solutions to apply to this problem. Some I've purchased and tried
(e.g.
cat facial pheromone or Feliway®), but none have worked. I have
researched electronic pet repellants and found a couple of such
products
that do have a proven track record. But these simply deter animals
from
entering or remaining in a certain area by emitting an ultrasonic
noise
(silent to humans) upon the detection of motion --any motion, by any
pet,
person, or thing, for any reason. Such a device would definitely
scare
the cat out of the house, but wouldn't meet with the cat's owner's
approval since it is not selective for specific problem behavior, and
she
wants the cat living indoors. Thus I need to develop a customized (yet
affordable) technical solution, such as would briefly emit an
ultrasonic
"noise" to startle the cat, but *only in response to wetting behavior*
by
the cat.

Therefore, helpful feedback/references/possible
plans/schematics/suggestions appreciated?

TIA,
Ken


relay switch
| |
E1--0 sensor 0-----------(+) 0---/ ----0
| Op Amp (out) ------relay coil---
---------|------------(-) |
| | Gnd
R1 R2
| |
gnd gnd


A simple Op Amp comparator circuit driving a relay would do it for you.
There needs to be only very little current to get the op amp to go high
at
the output. I like the aluminum foil fingers idea that was posted. It
is
cheap and easily replaces after the critter soils it.

I don't know what the resistance of cat piss is but it will help you
determine what value resistors are needed.. R1 and R1 should be equal.
I
am guess a 12V source and 100Meg resistors to start off with.. Look for
a
relay with a high coil resistance, They do make some "reed" relays that
take very little current to fire..

LOL, you are a troo loon!

Here's what he needs:

+6V>--+----------+---------+--------+-----------+
| | | | |
| | | [10K] |
| | | | |
[SENSOR] | +---|--[1M]--+ |
| | | | | |
| [10K]<--+--|+\ | E
| |POT | >------+--[600R]--B 2N4403
VIN>--+-------------------|-/ LM393 C
| | | | +--------NO
| | | +-----+ |
[100K] | | |K | O--> |<--NC
| | | [DIODE] [COIL]- -|
| | | | | O--COM
GND>--+----------+---------+--------------+-----+

Ground the unused inputs and output of the unused comparator, then
to set it up what you do is to run the pot all the way to ground,
attach the sensor and pee on it, and then adjust the pot until the
relay clicks in and then just a little bit more for good measure.

Then, you take the sensor out wash and dry it and put it back. The
relay can be used to trigger any "disciplinary" device, remembering
that Mark Twain said about cats, "Of all God's creatures, there is
only one that cannot be made the slave of the lash. That one is the
cat. If man could be crossed with a cat it would improve man but it
would deteriorate the cat."

--
John Fields
Professional Circuit Designer

LOL, you are a troo loon!

Lol, Can't argue with that..

But I did build this some years ago,(Not to monitor cat piss). 2
resitors,
op amp and I belive the relay was 5V with a 500ohm coil. Worked fine.
Light
goes on, Light goes off.....

But I am sure you will tell my why it dosen't work...

I used it in an old Ikagami studio camera. We had a rash of Plumbicon tubes
that has short lived filiments. I used the circuit to insert a light bulb
in the filiment circuit when the camera was put into standby mode to cut the
filiment current when the camera was not in use.

Could not have been luck because I don't have much of that...

Just a looney hack, I guess...

 

[DBLEXPOSURE]

I hadn't thought of using a layer of paper towel. Sounds a good idea as
the liquid has to go somewhere...Better to have an instant mop. As you
say, it will hopefully only be used a couple of times and is not the sort
of thing that you would want to keep around afterwards as a conversation
piece.

I assume that kittens do actually know when they are weeing? We may only
be training it to avoid walking on paper towels/shiny metal surfaces.
IIRC, several AI systems have failed due to the wrong choice of training
sets..

We always just rubbed there nose in it, a little swat and threw em in the
litter box. Didn't take long for them to figure out where to do there
business. They seem to prefer the litter box over the carpet. Hard to dig
a hole in the carpet I guess.. Harder to train the humans to change the
litter box regularly than it is to train the cat to use it.

 

[Bill Gray]

However, to keep it on topic, I modified the same idea a few years ago
to prevent my cat from digging in my rubber plant pot and peeing in the
resulting dirt on the carpet. I placed a wire grid (screen) on the
carpet under the pot, extending about 8" all around it. I put another
grid just below the surface of the dirt in the pot, and hooked each grid
to the poles of a small "electric fencer" circuit I had built. Not
enough to fry the kitty, but definitely enough to keep her from doing it
again. The next time the cat stood on the grid beside the pot with her
hind feet and started digging in the pot with her front paws, she got
the message quickly, and I removed the device.

Nels

"...the cat that sits down on a hot stove-lid. She will never sit down
on a hot stove-lid again - and that is well; but also she will never sit
down on a cold one anymore."
-- Mark Twain

 

[Pig Bladder]

On Fri, 26 Aug 2005 13:11:39 +0000, Ken Moiarty wrote:

Such a device would definitely scare the cat out of

the house, but wouldn't meet with the cat's owner's approval since it is not
selective for specific problem behavior, and she wants the cat living
indoors. Thus I need to develop a customized (yet affordable) technical
solution, such as would briefly emit an ultrasonic "noise" to startle the
cat, but *only in response to wetting behavior* by the cat.

So, finally, it comes to light that this is some babe, and she insists
on bringing "her" cat into your house if you want to get laid?

It ain't worth it. She's addicted to cat, and can never love a man. Lose
the bitch.

 

[Palindr☻me]

On Fri, 26 Aug 2005 13:11:39 +0000, Ken Moiarty wrote:

Such a device would definitely scare the cat out of



So, finally, it comes to light that this is some babe, and she insists
on bringing "her" cat into your house if you want to get laid?

It ain't worth it. She's addicted to cat, and can never love a man. Lose
the bitch.

That's life, if you want pussy, you have to have a cat...