Somehow our cats learned to drink from the faucet. We'd turn the water on for them, but they never turn it off
when they were done! I'm sure there are other cat owners out there with a similar problem. So, I built the Cat Faucet so the cats
could turn the water on and off for themselves. As a kit, I would rate this medium complexity. The electronics are simple and straight-forward
but you also need to do some mechanical work and some plumbing to complete the project, which raises the complexity.
Similar to the sinks that automatically turn on when you waive your hands under them, but for a different purpose.
Here's the externally visible parts. A small IR 'cat detector' sensor which senses when a cat is near and a bit of 1/4" plastic tubing providing
the water for the cats to drink. There's also an optional 'people detector' which you can use to stop the cat faucet
from turning on when a person puts their hands into the sink.
The key is positioning the sensor and tubing so that the sensor is engaged when the cat is drinking the water. There's about a 6"-12"
range on the sensor. It probably goes without saying but you also need somewhere for the extra water to drain!! So, all in all, a sink
installation like this works very well.
Here's another installation and different view of a Cat Faucet. This one installed in similar way, but on a different sink. The plastic
tubing is attached to the end of the faucet with tape and the sensor is pointing at the end of the tubing. Also notice how removal of the
drain control left an opening for both the tubing and the sensor wire. This allows the rest of the cat faucet to be located under the sink
without making any additional holes in the sink or the counter.
What goes under the sink is the water valve and the microcontroller. Here's a shot of the water valve. The valve
is a quarter turn ball-valve with a 3/8" O.D. compression fitting on each end. You can also see in this picture the 3/8" to 1/4" compression
adapters used
to attach the valve to smaller diameter plastic tubing. The left hand side is high-pressure tubing that connects to the house water.
The right hand side is low pressure tubing that runs up and out to the sink where the cats drink. Make sure you use high pressure tubing on the
inlet side!
A saddle valve with a 1/4" O.D. compression outlet is used to connect the Cat Faucet to the house water supply.
The saddle valve has a built-in needle valve which is used to adjust the maximum water flow. This configuration helps to reduce the
flow of water in the event the tubing ruptures or something else goes wrong.
This is the completed microcontroller that runs the Cat Faucet. The microcontroller limits the maximum 'On' time in case
something falls in front of the sensor. It also applies some hysteresis to the sensor so that as the cat moves around,
the valve isn't constantly turning on and off. The two pots on the left side of the board are used to adjust the R/C servo travel to
match the valve configuration.
If you want your own Cat Faucet here's to do. Order a circuit board, kit or assembled unit here and
then build and install. Note that even the assembled unit still requires some interesting design work since you will need to determine how
best to install the cat Faucet in your particular sink. Each sink will be different. Also consider, do you want to make additional holes
in the sink? Where can you get to a water source and how do you have to attach to it? All these things you will have to figure out even
with the assembled unit.
If you're purchased a board or full kit, the first thing to do is assemble the board. Otherwise, jump down to the installation
section below.
Putting the board together is a relatively easy soldering job. Just solder all the components onto the board (see pic on the right)
with the following exceptions:
The People Sensor is optional. If you're NOT using the People Sensor, either solder in the header and
place a shorting block between pins 1 and 3 or just solder in a jumper wire between those pins.
On v1.0 of the board, the pad holes are too small for the power jack. Bend up and trim the two
outside tabs and solder those tabs to the top surface of the board. The middle tab still goes thru the
board and is soldered on the bottom.
The more difficult part is constructing the valve. The block diagram on the left
shows an overview of what you need to build. Lay out the pieces first to make
sure you've got the orientation correct. Keep in mind that you the servo to pull the wire to close the valve. This way any
flex in the wire won't stop the valve from closing.
The push-rod wire between the servo and valve handle should go into one of the shorter
holes on the servo arm. The hole on the valve should be on the outer edge
of the valve handle. Make Z-bends on both ends of the wire to attach it to the servo arm
and the valve handle. Be careful to leave enough 'tail' on the Z-bend on the valve handle side
so that it doesn't catch on the bottom of the handle.
Manually rotate the servo almost to it's extreme
counter-clockwise position. This should be where the valve is fully closed. Once
assembled the 'Min' trim pot can be used to more accurately place the fully closed
position.
Manually rotate the servo approximately 90 degrees clockwise. If you've got everything
adjusted correctly, this should yield about a 30-45 degree rotation of the valve. You're
not shooting for 100% open! It's wise to do this adjustment before you permanently
attaching things to the 3/4" square aluminum tubing. Only after you've confirmed that things are
lined up correctly, should you permanently attach the valve and servo!
Here's two images of the servo and valve attached to the 3/4" square aluminum tube. One
image is with valve open, the other is valve closed so you can get an idea of the
range of motion you should be shooting for when you adjust the servo and valve
placement. If you look closely at the open position picture (the top one) you can see
the long tail on the Z-bend going thru the valve handle. Without this tail, when the valve
closes, the wire will tend to hang up on the bottom of the valve handle. That will jamb
the mechanism and cause all kinds of problems!
The tie-wraps are convenient during the initial assembly as you can make them tight enough to
hold things together, but still loose enough to slide things back and forth. Then
once things are aligned properly, squirt some superglue around the edges of the valve that are in
contact with the aluminum tube and cinch down it's tie-wraps. Be careful to keep the tie-wraps
off the 3/8" to 1/4" reducer since you'll need to be able to get a wrench on the nut to
tighten the connector to the plastic tubing.
The servo isn't super glued in (but you could do that). In this configuration I have
super glued aluminum L's underneath the mounting ears on the servo. This is mostly to
keep the servo from rotation due to the pressure applied to the valve handle. The tie-wrap
is only there to keep the servo positioned between the two L brackets.
Once you have the valve assembled, connect the servo to the controller board. Turn the
Min pot fully clockwise and the Max pot fully counter clockwise. Then short together the
pads labeled "Setup" and apply power. At this point the servo should start cycling back
and forth. Adjust the Min (closed) and Max (Open) pot so that on closure, the servo slightly
overdrives the valve. Adjust the Max pot so that the wire, hole and servo center post
almost align (see the top photo on the right). Once adjusted, remove power and you're
ready to install.
Installation
First and foremost determine how you are going to run the water tubing and the wiring
for the sensor(s). You need to place the valve so that the input tubing can be easily
connected to the water supply and the output tubing can be run into the sink. The cat
detector needs to be positioned such that a cat, when drinking, is within 6"-10" of the
front face of the sensor. If you're using the optional 'people detector' this needs to be
positioned so that a person using the sink will be within the same 6"-10" range. Don't forget
you also need to place the valve/controller unit within reach of power!
Once you have everything located, drill any necessary holes for routing tubing,
wiring and power. Then run the tubing, run the wires and connect the servo, cat
sensor and the optional People Sensor.
Connecting to the water supply can be a challenge. Using the saddle valve to attach
the cat faucet to the water supply has several advantages. First, you can place the saddle
valve just about anywhere you have access to a 3/8" to 1" O.D. tube water supply line. Second, you don't have
to shut off the water to install the saddle valve. Third, you can use the saddle valve to adjust
the water flow out of the cat faucet. You must have some kind of valve between the water supply
and the cat faucet valve to control the water flow. The cat faucet valve is not meant to control
the amount of water, only to turn the water on and off. The saddle valve accomplishes this nicely.
The yellow (signal) wire is pin 1 on the servo connector. Pin 2 is +DC Power, Pin 3 is Gnd. For the cat and People Sensor, the
connector is a separate plug for each wire. This helps in maneuvering the
wires thru very small holes. Wiring for the both sensors is the same. S1 is the connector
for the Cat Sensor and S2 is the connector for the People Sensor. Pin 1 is the signal
and is white or yellow. Pin 2 is +DC power and is the red wire. Pine 3 is ground and is
the black wire. Note if you're not using the optional People Sensor, make sure
pin 1 and pin 3 on S2 (the People Sensor) are shorted together. I suggest soldering
a small wire on the bottom of the board to short these pins together. You can then clip the
shorting wire later if you decide to add the People Sensor.
At this point, plug it in, the LED should start flashing. On startup, the controller
ensures the valve is closed and then it's ready to go. Wave your hand in front of the
Cat Sensor, the valve should open and say open for bit after your remove
your hand. Block the People Sensor and no amount of waving in front of the Cat Sensor
should turn on the water.
