> On 4/15/06, Bob Axtell <
EraseMEengineerspam_OUT
TakeThisOuTcotse.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
>
>
>> 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:
>>
>>> On 4/9/06, Bob Axtell <
engineer
spam_OUTcotse.net> wrote:
>>>
>>>
>>>> My wife bought a ceramic fountain. It has a pump that draws water
>>>> from the bottom and pumps it to the top, so the birds can bathe in it
>>>> and it srips down to the bottom again. Looks neat, works nice, kills
>>>> some of the road noise.
>>>>
>>>> The problem is that in So Arizona, the water evaporates so fast, I
>>>> can't discipline myself to keep it filled. So... I am gonna design a
>>>> slick way to sense when the water level is low so it can kick on a
>>>> solenoid and pump some back into it. I don't want to use anything
>>>> ugly, or big (like a float valve). I had in mind a non-contact sensor,
>>>> perhaps a capacitor. The whole sensor/solenoid deal could then
>>>> be automatic.
>>>>
>>>> What would work reliably? I am leaning toward a probe with two
>>>> insulated contacts, that I can make part of a tuned circuit; when
>>>> the water is missing between the probes, the frequency is at a
>>>> certain range, with the water between the probes, the frequency
>>>> is detuned. Another idea was to mount a tiny magnetic float in
>>>> a plastic tube, and when the float is high enough, it triggers a
>>>> hall device.
>>>>
>>>> Any other ideas?
>>>>
>>>>
>>> A fountain automation it can't be without a PIC. Telemetry, ultrasonic
>>> range finder, laser beams...using top DSP or ARM cores...
>>> :)
>>> Maybe a simple mercury sealed switch (floating on the water surface)
>>> connected directly (or using a relay) into your low power pump circuit
>>> ? No PIC, allowing a long distance to pump and safe histeresys. The
>>> smallest I've seen looks like a watch bulb.
>>>
>>>
>>>
>>>