automatic faucet - what kind of sensor?

[inetquestion]

I would like to build an automatic water faucet, but wasn't sure what
the sensor in a unit like the one below consists of. Here is a sample
picture:

http://www.airdelights.com/images/automatic_faucets/sf2300a.jpg

What kind of sensor do these faucets use? Would it work well outside?
I'm thinking of building an automatic water fountain for my dog which
would consist of mostly everyday parts. The goal is to take a sink
fixture and mount it upside down or sideways so the dog can reach it
easily. The water source would likely come from inside and be slightly
elevated from the exit point. The reason is so that once the valve has
shut off the water will drain out and prevent freezing.

TIA,

-Inet

 

[David Harmon]

On 3 Mar 2006 22:12:31 -0800 in sci.electronics.design,

I would like to build an automatic water faucet, but wasn't sure what

Do not post copies of your question in multiple newsgroups. Pick
one.

 

[Genome]

I would like to build an automatic water faucet, but wasn't sure what
the sensor in a unit like the one below consists of. Here is a sample
picture:

http://www.airdelights.com/images/automatic_faucets/sf2300a.jpg

What kind of sensor do these faucets use? Would it work well outside?
I'm thinking of building an automatic water fountain for my dog which
would consist of mostly everyday parts. The goal is to take a sink
fixture and mount it upside down or sideways so the dog can reach it
easily. The water source would likely come from inside and be slightly
elevated from the exit point. The reason is so that once the valve has
shut off the water will drain out and prevent freezing.

TIA,

-Inet

Wufff Wuuuffff Wufff Bark Wufff Rufff Ruff Roowwell.

Wuff

 

[[email protected]]

On 3 Mar 2006 22:12:31 -0800 in sci.electronics.design,


Do not post copies of your question in multiple newsgroups. Pick
one.

I only got one copy of his question. Are you sure your newsreader is
working properly?

You can do this with an IR LED and photodiode mounted next to each
other so that an object in the target area will be illuminated by the
LED. The photodiode is positioned to detect the reflected light, so the
LED should not be able to directly illuminate it (for instance, by
reflecting off of the back of a filter).

Depending on the ambient lighting and the objects in the installation,
you may have to trigger the valve on a rise, fall, or change in
reflected light. A porcelain sink is pretty reflective, so a typical
sensor probably looks for a drop as a pair of hands obstructs the light
path.

You will also have to put some kind of low pass filtering on there to
eliminate changing sunlight conditions.

Another approach is to use a patterned emitter. In this case the
emitter is not fed with a steady current, but a square wave of around
30 kHz. Any light reaching the photodiode that is modulated at this
frequency is guaranteed to be reflected from the emitter. Passing the
photodiode output through a high-pass filter will eliminate sunlight,
car headlights, streetlamps, etc. This is how TV remote controls work;
you can in fact buy an IR remote receiver module for a couple dollars;
however, many of them will not work in steady-state conditions (i.e.,
they were designed to measure thousands of bits per second, not dogs
per hour.)

There are a few ways to cope with this time scale problem; I can keep
rambling if I'm getting you any closer to a solution.

 

[Rich Grise]

I only got one copy of his question. Are you sure your newsreader is
working properly?

It looks to me like David Harmon has seen the same question posted
to another newsgroup, or more. This is called "multi-posting", and
is frowned upon. In a case where there are up to five possible newsgroups
of interest, the accepted USENET convention is to crosspost - i.e., send
one message with up to five comma-separated newsgroups in the "newsgroups"
header. That way, others can benefit from the answers; and if an answer is
group-specific, or the thread diverges, then we use the "followups-to"
header to narrow the scope of the branch.

And there's only one copy of the message body on the server; only the
header gets duplicated.

Hope This Helps!
Rich

 

[Pig Bladder]

I'm thinking of building an automatic water fountain for my dog ...

If you can't be bothered to water your own dog, then you don't deserve to
have a pet.

 

[Genome]

If you can't be bothered to water your own dog, then you don't deserve to
have a pet.

Wooff

Wuff

 

[[email protected]]

I would like to build an automatic water faucet, but wasn't sure what
the sensor in a unit like the one below consists of. Here is a sample
picture:

http://www.airdelights.com/images/automatic_faucets/sf2300a.jpg

What kind of sensor do these faucets use? Would it work well outside?
I'm thinking of building an automatic water fountain for my dog which
would consist of mostly everyday parts. The goal is to take a sink
fixture and mount it upside down or sideways so the dog can reach it
easily. The water source would likely come from inside and be slightly
elevated from the exit point. The reason is so that once the valve has
shut off the water will drain out and prevent freezing.

The example you show probably relies on an infra-red-light-emitting
diode to illuminate a pair of hands or a dog, and an
infra-red-sensitive photo-diode to dtect the light they reflect (or
perhaps the light that a reflective background doesn't reflect).

As stickyfox says, such systems normally modulate the light emitted at
a frequency in the kiiloherz range, not unlike a TV remote. Unlike a TV
remote receiver, you can use synchronous detection to reject external
light sources.

An alternative approach, used in some automatic hand-driers, is to
measure the capacitance between a pair of extended electrodes on either
side of the target volume. If you put a decent sized lump of water - a
human hand or the head of a dog - into this volume, the capacitance
between the electrodes is increased.

You don't want to make the system too senstive - if the column of water
coming out of the tap increased the capacitance above the threshold
value, the tap would turn on okay, but would never turn itself off.

 

[John Larkin]

I would like to build an automatic water faucet, but wasn't sure what
the sensor in a unit like the one below consists of. Here is a sample
picture:

http://www.airdelights.com/images/automatic_faucets/sf2300a.jpg

What kind of sensor do these faucets use?

Probably a PIR, passive thermal-electret infrared sensor, like a
security system sensor or one of those automatic light switches.

Would it work well outside?
Should.

I'm thinking of building an automatic water fountain for my dog which
would consist of mostly everyday parts. The goal is to take a sink
fixture and mount it upside down or sideways so the dog can reach it
easily. The water source would likely come from inside and be slightly
elevated from the exit point. The reason is so that once the valve has
shut off the water will drain out and prevent freezing.

I have a sensor like that in my garage. It replaces the regular light
switch, and has adjustable sensitivity and on time. So when I walk
into the garage with my hands full of power tools or the stinky
kitty-litter bin, the light goes on for me. Get something like that at
Home Depot, maybe an outdoor version, and use it to switch a
washing-machine solenoid valve. A small leak would take care of the
freeze-drain situation.

Why doesn't anybody sell a small consumer-type PLC? It could have a
couple of contact closures in/out, a temp sensor, a light sensor, a
PIR, maybe a remote. You could program it from a PC. That could be
dirt cheap, and I bet lots of people would have use for them around
the house.


John

 

[Donald]

Probably a PIR, passive thermal-electret infrared sensor, like a
security system sensor or one of those automatic light switches.




http://www.waterdogpetfountain.com/



I have a sensor like that in my garage. It replaces the regular light
switch, and has adjustable sensitivity and on time. So when I walk
into the garage with my hands full of power tools or the stinky
kitty-litter bin, the light goes on for me. Get something like that at
Home Depot, maybe an outdoor version, and use it to switch a
washing-machine solenoid valve. A small leak would take care of the
freeze-drain situation.

Why doesn't anybody sell a small consumer-type PLC? It could have a
couple of contact closures in/out, a temp sensor, a light sensor, a
PIR, maybe a remote. You could program it from a PC. That could be
dirt cheap, and I bet lots of people would have use for them around
the house.


John

 

[Fred Bloggs]

The example you show probably relies on an infra-red-light-emitting
diode to illuminate a pair of hands or a dog, and an
infra-red-sensitive photo-diode to dtect the light they reflect (or
perhaps the light that a reflective background doesn't reflect).

As stickyfox says, such systems normally modulate the light emitted at
a frequency in the kiiloherz range, not unlike a TV remote. Unlike a TV
remote receiver, you can use synchronous detection to reject external
light sources.

An alternative approach, used in some automatic hand-driers, is to
measure the capacitance between a pair of extended electrodes on either
side of the target volume. If you put a decent sized lump of water - a
human hand or the head of a dog - into this volume, the capacitance
between the electrodes is increased.

You don't want to make the system too senstive - if the column of water
coming out of the tap increased the capacitance above the threshold
value, the tap would turn on okay, but would never turn itself off.

Heheh-that's why they all have timers.

 

[onurco]

http://groups.google.com/group/sci....t&q=electronic+faucet&rnum=1#c4ad2ed5d5751447

 

[Bob Monsen]

I would like to build an automatic water faucet, but wasn't sure what
the sensor in a unit like the one below consists of. Here is a sample
picture:

http://www.airdelights.com/images/automatic_faucets/sf2300a.jpg

What kind of sensor do these faucets use? Would it work well outside?
I'm thinking of building an automatic water fountain for my dog which
would consist of mostly everyday parts. The goal is to take a sink
fixture and mount it upside down or sideways so the dog can reach it
easily. The water source would likely come from inside and be slightly
elevated from the exit point. The reason is so that once the valve has
shut off the water will drain out and prevent freezing.

Search for Sanyo GP2D12. It is an IR sensor used in (among other thing)
bathroom automation. Simple to use, will work outside, and fairly cheap,
like $10.

However, it should be easy to teach the dog to stand on a 2'x2' plate of
some kind... You could do it without electronics that way, so you wouldn't
need a power source.

--
Regards,
Bob Monsen

The most beautiful thing we can experience is the mysterious. It is
the source of all true art and all science. He to whom this emotion is
a stranger, who can no longer pause to wonder and stand rapt in awe,
is as good as dead: his eyes are closed.
Albert Einstein (1879 - 1955)

 

[Bob Monsen]

Search for Sanyo GP2D12. It is an IR sensor used in (among other thing)

^^^^^^^^^^^^

Sharp GP2D12

http://www.acroname.com/robotics/parts/R48-IR12.html

--
Regards,
Bob Monsen

The most beautiful thing we can experience is the mysterious. It is
the source of all true art and all science. He to whom this emotion is
a stranger, who can no longer pause to wonder and stand rapt in awe,
is as good as dead: his eyes are closed.
Albert Einstein (1879 - 1955)

 

[Don Lancaster]

Probably a PIR, passive thermal-electret infrared sensor, like a
security system sensor or one of those automatic light switches.






John

I believe the leader in the field by far is Qprox

http://www.qprox.com/products/index.php

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com