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'[OT]: Fountain Project- Design Done... Thanks'
2006\04\15@150208 by Bob Axtell

face picon face
OK, here is the design:

At the Fountain:

1. At the fountain is a white plumbing pipe, very thin wall. This one has a
water connection (ribbed stub) on the side and has an open top and bottom.
It is the water filling method, and doubles as the water sensor as well.
This looks to be a standard plumbing fixture, cost about $1 USD.

2. The outside of the thin wall pipe has 4 "plates" of copper adhesive foil,
rectangles, two above the other two. These plates do NOT contact each other
and are 2"x W by 2" high. There should be a 1/10" gap between the
plates. Small
insulated wires  are soldered to the plates, going up on the outside of
the plates
to the top of the pipe.

3. Craft stores here in the Colonies named Michael's sell a two-part
clear epoxy
that hardens rock hard. A batch should be made up and the lower part of
the pipe,
including all of the copper, should be dipped several times until it has
a coating of
about 1-1.5mm of plastic. Allow this to harden for 24 hrs. You can now
run tests
on the water sensor, if you like. NO conductor touches the water, EVER.

4. The water sensor is composed of the 4 plates of the water pipe. The
lower two
plates are to be tied (1) to a PIC input and (2) to PIC GND . The upper
two plates
are tied to another PIC input and also to PIC GND. The upper plates are
the reference
capacitor and the lower plates are the sensor capacitor.

5. Water in the fountain floods the lower set of plates , INSIDE the
pipe.  This dramatically
increases the capacitance of the lower "capacitance". The water does NOT
reach the  upper
plates, which act as a reference; because the "PIC" input capacitor
measuring method is subject
to temperature variants, the fact that both caps are measured allows us
to make a more reliable
judgment. The ratio of ACTIVE count to REF count is about 4:1 with water
detected. Our water
is pretty ho-hum, has a little magnesium and a little chlorine.

6. At the top of the pipe is a PIC10F200 on a 1/4" x 1/2" PCB encased in
plastic epoxy. The
PIC, when powered, makes several capacitor measurements by HOW MANY TEST
LOOPS
are needed before the capacitor no longer holds a charge. The PIC will
make 16 passes for
each capacitor, then send back both averages to the main control unit.
The data is sent back
using Manchester code, with a bit time of approx 5mS/bit. The data
stream is two '1' start
bits, followed by 8 REFERENCE data bits, followed by 8 SENSOR data bits,
followed by a
dummy STOP bit. This keeps repeating as long as it is powered. So the
decision about the
water level is decided AWAY from the water.

The Controller to Fountain Cable:      

1. The water sensor itself needs 5V, GND, and an output signal, so a
cable of 4 conductors is
used, GND is doubled and the cable is shielded. This will be about 25'
(7m) long.

2. The water pump needs AC mains (here 115VAC 60Hz 30w).

These two cables will be enclosed into a waterproof outdoor conduit.
This will be buried 12"
down.

Note: there will be a water hose as well; I am using flexible hose
enclosed by neoprene split
hose, and also buried at 12". The neoprene will prevent the other hose
from being closed by
the weight of the soil above it. The hose can be quite small; I am using
1/4" hose. This keeps
the fountain filled with water.

Controller:

1. Mounted on the side of the house is a small waterproof NEMA box
containing electronics
and controls. A small waterproof PB switch, GREEN/RED LED,  and
photodiode is mounted
on the outside.

2. Two 30A 12V relays operate the PUMP and the WATER SOLENOID. While
neither of
these draw 30A, a larger contact area in general means a longer life.
Internally the 115VAC
mains is protected by an internal 1A "slowblow" fuse.

3. A internal PCB contains the following:  a PIC12F675  DIP (socketed) ,
the two 12V relays,
a 12V & 5V power supply for  the PCB and fountain sensor, a photodiode
(for sensing daylight),
and a couple of cables & connectors.

4. Action: (A) the fountain does NOT pump during the night, as the
photodiode detects no daylight.
But during the night, every 15 minutes, the water sensor turns on and
the water level is determined.
If water is needed, the sensor is turned off and the water flows for
about one minute. This cycle repeats
all night.

5. Action: (B) during the day, the fountain pumps. Every 5 minutes, the
water sensor turns on and the
water level is determined; if water is needed, the sensor is turned off,
water is turned on for one minute.
The reason to do this more often is that during the day, evaporation is
MUCH higher.

6. The RED LED will wink if both sensors appear to be identical; this
might indicate that the water has
run totally dry; this will also cause the pump to shut off.

7. Normally operation is automatic; if the switch is pressed, whatever
is happening will stop for one hour.
For example, if the pump was running normally, it will now STOP. If it
was previously stopped manually,
it will now start running again. This is normally used to allow the user
to clean bird feathers out of the
fountain.

- - -

Flames expected.

--Bob



Vasile Surducan wrote:
{Quote hidden}

2006\04\15@152237 by Bob Axtell

face picon face
I'm laying out PCBs next week. I plan to get 10 PCBs made. If
anybody wants a coupla PCBs let me know. These will be non-SS/
non-SM, but 2-sided. Not very tight layout. All SMT. The tiny
sensor board will have 5 points in a row so that the PIC10F200
can be programmed after tacking on the wires, and it will need
to be "sawed away" from the control PCB.

BTW: I have located cheap sources for everything, even the relays
(ZETTLER AZ971, app $1.50) and the washing machine filler control
solenoid (about $4).

--Bob


Bob Axtell wrote:
{Quote hidden}

2006\04\16@055703 by Vasile Surducan

face picon face
On 4/15/06, Bob Axtell <engineerspamKILLspamcotse.net> wrote:
> OK, here is the design:

Very nice design Bob !

Now the problem could be if indeed your wife will be happy with this.
You said it's her fountain (or just her ideea), and maybe she expects
manually water fill by your hands, as a loving prove. Wifes behaviour
is quite unexpected sometimes...
I hope she will be extremely satisfied by your project, as we are.
:)

greetings,
Vasile

{Quote hidden}

> -

2006\04\16@192052 by Bob Axtell

face picon face
She will be happy with IT. _I_, of course, busy with projects, don't
spend enough time with her, a very bad thing...

--Bob

Vasile Surducan wrote:
{Quote hidden}

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