Empty water bottle detector

[rexxar]

My rabbits have two water bottles on the side of their cage, and it's kind of hard for us to tell when they're empty, so I wanted to set up a small project to detect when they're empty, and beep at us to remind us to refill them.

I can't put any holes into the bottles, that would break the vacuum and they'd leak everywhere, so I was thinking I could float a magnet in the water and have a reed switch at the bottom to detect it. Unless there's a better way of doing it?

I'm going to have a 555 beep piezo buzzer to alert us, but I'd like it to wait about 5 or 10 minutes between beeps. Is there a simple way to do that?

[NiHaoMike]

If the rate at which they empty is predictable, what about just use an alarm clock to remind you at a good time?

Another option is to add two strips of foil tape to the outside of the bottle, making a capacitor.

[JackOfVA]

I can think of complicated ways to detect level without penetrating the bottle wall - such as a pair of copper or aluminum strips in parallel applied to the outside bottle wall and looking for change in capacitance between the two strips with a trip point when capacitance/water level reaches some certain point.

But, if you are looking for a simple detector perhaps you could support the bottle(s) with springs so that when the bottle level drops below some particular level, the bottle will be pulled up by the spring such that a magnet operates a reed switch. Totally non-intrusive and relatively simple to implement the switch.

Or you might be able to use an LED and photo sensor - the water will refract the LED's light beam (as well as the bottle wall, of course) so that the LED spot will shift position depending on whether the path is bottle wall - water - bottle wall or bottle wall - air - bottle wall. This should also be relatively easy to implement with a self-contained light detector / switch.

[AndyC_772]

I think whatever technique you use to detect the liquid level, you'll want a real-time clock in the system somewhere. Otherwise you'll keep getting woken up at stupid o'clock in the morning by a bleeping rabbit hutch... the novelty will wear off quite quickly IMHO.

[rexxar]

I can think of complicated ways to detect level without penetrating the bottle wall - such as a pair of copper or aluminum strips in parallel applied to the outside bottle wall and looking for change in capacitance between the two strips with a trip point when capacitance/water level reaches some certain point.

That sounds interesting, there'd also be no wires near the floor for them to chew on. How would you implement this? Would it just be easiest to use an Arduino?

I think whatever technique you use to detect the liquid level, you'll want a real-time clock in the system somewhere. Otherwise you'll keep getting woken up at stupid o'clock in the morning by a bleeping rabbit hutch... the novelty will wear off quite quickly IMHO.

I was going to use a photoresistor to do this. I didn't want to get a micro controller involved, mostly because I don't know C 

[mariush]

Two wires inside the bottle, insulated almost up to the bottom... measure resistance every few minutes. If water, you get one resistance, if air (and uninsulated tips dry up) then you have another resistance.

Another idea would be to have some kind of material that reflects/refracts light differently when wet, then use infrared emitter and receiver and if infrared goes through you know there is (or isn't water at that point).

 Maybe use some of that material that's used in lcd filters ... tie something that floats in the corner of a square of that material, when bottle is full the material stays up, when you're low on water, it goes down over the other material making it opaque, blocking light.

[filip_cro]

If you are god at physic try using reflection from surface when water level is low. Maybe floating mirror would work better? Or barier which can float and block light in some moments?

[houdini]

Why do all that stuff just mount it with an small insulating spring separating the hook from another plate when it empty it will be light enough to push it up so either have this make or break a contact that triggers a whatever.

[deth502]

Why do all that stuff just mount it with an small insulating spring separating the hook from another plate when it empty it will be light enough to push it up so either have this make or break a contact that triggers a whatever.

wasmy first thought as well, but as i was pondering a reply whilst reading the others, i had time to think on it, and i believe that the mere act of the rabbits drinking from it would jostle it around enough to give enough false signals to make it unreliable.

[codeboy2k]

Why do all that stuff just mount it with an small insulating spring separating the hook from another plate when it empty it will be light enough to push it up so either have this make or break a contact that triggers a whatever.

wasmy first thought as well, but as i was pondering a reply whilst reading the others, i had time to think on it, and i believe that the mere act of the rabbits drinking from it would jostle it around enough to give enough false signals to make it unreliable.

Debounce it LOL  No really!

[Skimask]

Motion switch and a watchdog timer.  Motion switch resets the watchdog timer.  Watchdog timer triggers the alarm.

Rabbits drink water, move around, reset the watchdog timer.
Water runs out, eventually rabbits pass out from lack of water, watchdog timer runs out, alarm activates.
Simple eh? 

[JackOfVA]

I can think of complicated ways to detect level without penetrating the bottle wall - such as a pair of copper or aluminum strips in parallel applied to the outside bottle wall and looking for change in capacitance between the two strips with a trip point when capacitance/water level reaches some certain point.

That sounds interesting, there'd also be no wires near the floor for them to chew on. How would you implement this? Would it just be easiest to use an Arduino?

I think whatever technique you use to detect the liquid level, you'll want a real-time clock in the system somewhere. Otherwise you'll keep getting woken up at stupid o'clock in the morning by a bleeping rabbit hutch... the novelty will wear off quite quickly IMHO.

I was going to use a photoresistor to do this. I didn't want to get a micro controller involved, mostly because I don't know C 

A pair of foil traces (burglar alarm foil, or copper foil from the arts and craft shop) applied to the outside of the bottle and then taped or glued into place.  The electric field between the two foils will be both inside and outside the bottle.   And some of the field will be within the water.  Hence the capacitance will be a function of the water level.

There are LOTS of questions about the real life usability of this idea - such as whether the change in capacitance will be large enough to reliably measure.  With the right test gear, it would be simple enough to toss a prototype together and use a capacitance meter to measure the foil strip to foil strip capacitance with various water levels. Would also want to look at stability with temperature and a few other things before deciding it's the right way to go.  It's elegant but a simple solution has more going for it than an elegant but unreliable approach.

Another idea would be to use one of the robot ultrasonic distance sensors - since the speed of sound is much greater in water, if you measure the distance across the bottle diameter it will be much smaller when the sound path is in water than when the water level drops below the sensor.

https://www.bananarobotics.com/shop/US-100-Ultrasonic-Distance-Sensor-Module?gclid=CJ-b2LaQ8roCFcTm7Aod5G0AfQ

This sensor has both a digital and analog output - so you could use a microcontroller of whatever flavor you prefer or it could be done with a simple comparator and an RC filter network. 

Again, lots of details to pay attention to here, but it's probably a safer bet than measuring capacitance.

[rexxar]

I can think of complicated ways to detect level without penetrating the bottle wall - such as a pair of copper or aluminum strips in parallel applied to the outside bottle wall and looking for change in capacitance between the two strips with a trip point when capacitance/water level reaches some certain point.

That sounds interesting, there'd also be no wires near the floor for them to chew on. How would you implement this? Would it just be easiest to use an Arduino?

I think whatever technique you use to detect the liquid level, you'll want a real-time clock in the system somewhere. Otherwise you'll keep getting woken up at stupid o'clock in the morning by a bleeping rabbit hutch... the novelty will wear off quite quickly IMHO.

I was going to use a photoresistor to do this. I didn't want to get a micro controller involved, mostly because I don't know C 

Another idea would be to use one of the robot ultrasonic distance sensors - since the speed of sound is much greater in water, if you measure the distance across the bottle diameter it will be much smaller when the sound path is in water than when the water level drops below the sensor.

https://www.bananarobotics.com/shop/US-100-Ultrasonic-Distance-Sensor-Module?gclid=CJ-b2LaQ8roCFcTm7Aod5G0AfQ

This sensor has both a digital and analog output - so you could use a microcontroller of whatever flavor you prefer or it could be done with a simple comparator and an RC filter network. 

Again, lots of details to pay attention to here, but it's probably a safer bet than measuring capacitance.

That sounds like a good idea, but Google tells me that rabbits can hear up to 40-45kHz, so I'm afraid the noise would scare them away from their cage. I tried it on them, and a ~40kHz tone freaked them out, so that's not gonna work.

I was messing around with an IR LED and if I get the angle just right, I can get the light to bounce off the surface of the water. I think this will work for level detection, but that still leaves the issue of the long interval between alerts. Would a 555 work for such a long interval?

[jeremy]

Um, perhaps I'm crazy for suggesting this, but why not just weigh it? Buy one of these cheap chinese scales, hop inside and mod it a little with a Schmitt trigger.

I've done this before...I needed to see how much water was in a container....

[ElektroQuark]

Change water in a daily basis, they need fresh water.

[Tris20]

Two metal rods vertically inside the bottle. Both full insulated except one is exposed at the top(in air), the other exposed at the bottom( submerged). When resistance of bottom exposed rod is equal to the resistance of top exposed rod then the bottom is now exposed to air, therefore empty. Pretty sure this is along the same lines as other suggestions but this is how I would do it. But the device would also go off if you filled the bottle too much and submerged the top exposed rod.

Also, +1 for the timer. You don't want this going off at midnight

[deth502]

Change water in a daily basis, they need fresh water.

not playing the grammar police, but from your sig line i'm guessing your trying to learn. should be "on a daily basis" as in doing it on a schedule, or doing it on time.

[dannyf]

Empty water bottle detector

Two pages of sophisticated technological solutions to a problem that can be simply solved with love, care and responsibility.

[ddavidebor]

Change water in a daily basis, they need fresh water.

not playing the grammar police, but from your sig line i'm guessing your trying to learn. should be "on a daily basis" as in doing it on a schedule, or doing it on time.

Policeman, that's a international forum, not british language fan club...

[Alana]

Empty water bottle detector

Two pages of sophisticated technological solutions to a problem that can be simply solved with love, care and responsibility.

One hand - you are correct, other hand - this is interesting tech project anyway.
Btw when i had guinea pigs no sensors were needed, when hungry they made more noise than all my buzzers put together.

[AndyC_772]

Policeman, that's a international forum, not british language fan club...

You did see the signature right below the post in question, right?

I'm not an English native speaker, please correct me if I write something wrong

[ElektroQuark]

Change water in a daily basis, they need fresh water.

not playing the grammar police, but from your sig line i'm guessing your trying to learn. should be "on a daily basis" as in doing it on a schedule, or doing it on time.

Thank you VERY much.


On the subject:

A spring with a switch could do the job: water reservoir pending of the spring closing the switch under it. The spring should be strong enought to elevate the reservoir when it is empty releasing the switch.


Edit:

Sorry, I see now it was already suggested.

[BillyD]

Oops, just realised that rexxar had already thought of my suggestion about IR led and receiver.

[rexxar]

Those poor rabbits

As has been mentioned, show some love, take care of them properly. At the very least change their water once a day (every day) for fresh. Why have them if you don't want to have anything to do with them?

That's quite insulting, actually. I do take care of my rabbits, which is why I've paid hundreds of dollars to have them spayed/neutered and given them my entire living room. Their cage is where their food, water, and litter box is, it's always open. You don't know how I treat my rabbits, don't make assumptions. Besides, I see no reason to change the water in a sealed, shaded container every day, so long as I wash it between fillings. Ever bought bottled water? Did you empty and refill all the bottles daily so they're "fresh"?

I'm very busy with work and school so I sometimes don't notice the bottle is empty until the rabbits tell me, so I'd like to have a reminder. I thought this would be a fun project, and I'd learn some more about 555s, or micros, or whatever I decided to implement.

So, thanks for your input, but I'm pretty sure I know more about rabbit health than you do.

[fcb]

Two metal rods vertically inside the bottle. Both full insulated except one is exposed at the top(in air), the other exposed at the bottom( submerged). When resistance of bottom exposed rod is equal to the resistance of top exposed rod then the bottom is now exposed to air, therefore empty. Pretty sure this is along the same lines as other suggestions but this is how I would do it. But the device would also go off if you filled the bottle too much and submerged the top exposed rod.

Also, +1 for the timer. You don't want this going off at midnight

You will form a electrolysis cell, and likely strip metal ions from the electrodes, potentially poisoning your bunnies.  If you really must use electrodes, then only apply a small current on an infrequent basis (perhaps 0.1 seconds every hour, etc...) to make your measurement.

Depending on your level of expertise and/or motivation, and the assumption that you are looking at this as a challenge, here are some other ideas:
1. Optical, using the change in refractive index between air/water to alter the light path.
2. TDR - time domain reflectometry, wind a tight coil of wire on a hollow-former.  Send down a fast pulses and measure the time they take to return (easier than it sounds, and you can average it over perhaps 1E6 pulses).
3. Wind a coil round the outside of the bottle, use this in a colpitts oscillator and measure the frequency change.
4. Put a colored ball in the bottle, use a webcam with something like the roborealm/opencv machine vision.

[lapm]

Well how about low tech solution? Colorful plastic ball that floats in water, assuming you don't do daily fresh water change. Not sure where one might get such, toy stores maybe?

[GK]

This is probably the best solution:

http://www.taste.com.au/recipes/29437/tuscan+rabbit+with+pancetta+and+rosemary

[Tris20]

Hmm, thanks for pointing out the poisoning!

Why not just use something like smart card technology. I'm not to informed on it but from what I gather it's just a coil with a tiny chip. Put a coil inside a plastic float, put a sensor at the bottom, when the water is empty the sensor will detect the coil is in range and Bob's your uncle!



If anyone could expand on this with potential values for the coil length and frequency etc it would be appreciated. I don't do Electromagnetics till next semester

[strangelovemd12]

So far your initial suggestion looks to be the best.  But would "breaking the vacuum" really cause the bottle to leak?  I am thinking of the standard inverted plastic bottle with a metal tube and a little ball in the end.  Doesn't the water pressure just push against the ball, sealing the opening, then the animal pushes the ball back opening the check valve to drink?  I do remember this type of bottle leaking, but I always assumed it was the low quality seal from the little ball in the spout.  I  cannot imagine the rabbits are sealing their mouths around the spout and sucking out the water.

I'm also confused on all this fresh water business.   Unless these fools are ordering cylinders of hydrogen and burning it in a nonreactive chamber with a perfectly stoichiometric O2 mix, I think they are full of it.  As long as the bottle is regularly cleaned/disinfected the water isn't going to go stale, or any other thing detrimental to the health of your rabbits.   For all we know changing the water bottle more frequently than is necessary burdens poor bunny with undo mental stress as the source of nourishment known to revitalize it's precious bodily fluids is ripped from it's comfortingly static world.  Shame on all you more-frequently-than-is-necessary-water-changers.

[ddavidebor]

Policeman, that's a international forum, not british language fan club...

You did see the signature right below the post in question, right?

I'm not an English native speaker, please correct me if I write something wrong

Aah, no, my fault.

Please don't arrest me for justice interference. :-)

[AndyC_772]

Lol No problem... just don't let the Welsh hear you use the phrase "British language", you'll have a war on your hands!!

[Alana]

Went to pet store to look at bunny watering stuff and got and idea.
Laser pointer LED as light source takes care of most of the optics and it should be cheap to get.
It should give strong signal on photodetector and make it immune to ambient light change.
The only problem would be how to prevent laser from shining into wabbits eyes - for obvious reasons, but i think it could be done with proper mechanical assembly.
Cork... if its from wine bottle it is non-toxic to humans and should be ok for wabbits as well - provided that you wash away wine residue with hot water.
 

[IanB]

should be "on a daily basis" as in doing it on a schedule, or doing it on time.

And just to confuse things even more, usage can also vary by location. As a British speaker I would favour "doing it to a schedule" over "doing it on a schedule".

And now back to your regularly scheduled programming... 

[rexxar]

Two metal rods vertically inside the bottle. Both full insulated except one is exposed at the top(in air), the other exposed at the bottom( submerged). When resistance of bottom exposed rod is equal to the resistance of top exposed rod then the bottom is now exposed to air, therefore empty. Pretty sure this is along the same lines as other suggestions but this is how I would do it. But the device would also go off if you filled the bottle too much and submerged the top exposed rod.

Also, +1 for the timer. You don't want this going off at midnight

You will form a electrolysis cell, and likely strip metal ions from the electrodes, potentially poisoning your bunnies.  If you really must use electrodes, then only apply a small current on an infrequent basis (perhaps 0.1 seconds every hour, etc...) to make your measurement.

Depending on your level of expertise and/or motivation, and the assumption that you are looking at this as a challenge, here are some other ideas:
1. Optical, using the change in refractive index between air/water to alter the light path.
2. TDR - time domain reflectometry, wind a tight coil of wire on a hollow-former.  Send down a fast pulses and measure the time they take to return (easier than it sounds, and you can average it over perhaps 1E6 pulses).
3. Wind a coil round the outside of the bottle, use this in a colpitts oscillator and measure the frequency change.
4. Put a colored ball in the bottle, use a webcam with something like the roborealm/opencv machine vision.

I've gone with #1. I discovered that if I point the LED and receiver at each other, put them so the curve of the bottle just blocks them, the water refracts the light out to the side, but the air lets it go through.

I got some opamps in the mail today, so I decided to learn how those work, and I think it's a much better solution than amplifying the signal from the receiver with two NPNs..

I've attached a schematic of what I've built. I'm sure there's plenty of errors, but this is the first time I've used an opamp, so don't make fun of me! It works well, gives about a 1 second buzz every 15 minutes or so. Is there a good place to stick a photoresistor in this circuit to make it not go off when it's dark?

[rexxar]

So far your initial suggestion looks to be the best.  But would "breaking the vacuum" really cause the bottle to leak?  I am thinking of the standard inverted plastic bottle with a metal tube and a little ball in the end.  Doesn't the water pressure just push against the ball, sealing the opening, then the animal pushes the ball back opening the check valve to drink?  I do remember this type of bottle leaking, but I always assumed it was the low quality seal from the little ball in the spout.  I  cannot imagine the rabbits are sealing their mouths around the spout and sucking out the water.

The ball is held down with water pressure, but it doesn't seal the nozzle at all. The vacuum inside the bottle is what holds the water in. When the ball is held up against the opening, it makes the opening so small that surface tension holds the water in, but when you move the ball, there's enough room for a droplet to form.

Trust me, if you don't seal it well enough (or it just has a crappy seal), these bottles can make a mess 

[daveatol]

not playing the grammar police, but from your sig line i'm guessing your trying to learn. should be "on a daily basis" as in doing it on a schedule, or doing it on time.

While maybe not everyone can agree if you want your project to be on schedule or to a schedule (both sound fine to me), I think everyone will agree that "you're" should be used to mean "you are", rather than "your" as you've written.

I've gone with #1. I discovered that if I point the LED and receiver at each other, put them so the curve of the bottle just blocks them, the water refracts the light out to the side, but the air lets it go through.

I got some opamps in the mail today, so I decided to learn how those work, and I think it's a much better solution than amplifying the signal from the receiver with two NPNs..

I've attached a schematic of what I've built. I'm sure there's plenty of errors, but this is the first time I've used an opamp, so don't make fun of me! It works well, gives about a 1 second buzz every 15 minutes or so. Is there a good place to stick a photoresistor in this circuit to make it not go off when it's dark?

Well done for making it work. There are some errors in your schematic. The resistor connecting to pin 7 on each 555 is in the wrong position. You're missing a connection to pin 2 of the lower 555.

You could put the photoresistor between the opamp and the 2n2222; when it's dark, there won't be enough current to power the 555. It's not a good solution, but should "work". A perhaps better solution would be to connect it into the timing portion of the first 555 so that it beeps more quickly when it's light, and not at all when it's dark.

Personally, I'd probably try your original solution of using a magnetic float and reed switch or have the whole bottle hanging on a sprung microswitch,  for the sake of zero power usage and simplicity.

[GeoffS]

This is probably the best solution:

http://www.taste.com.au/recipes/29437/tuscan+rabbit+with+pancetta+and+rosemary

 
As an Australian, I'd have to agree that the only good rabbit is a dead one.   

[SeanB]

I feel like some as well. Always was threatening to eat Wodger Wabbit, but never did so and he died from old age.

[deth502]

While maybe not everyone can agree if you want your project to be on schedule or to a schedule (both sound fine to me), I think everyone will agree that "you're" should be used to mean "you are", rather than "your" as you've written.

argh!! you caught me!! thats a pet peeve of mine, i cant believe i did that. the ' key on my keyboard is not my friend, so i usually just skip it rather than go through the frustration of getting it to work unless i really have to, so i mostly leave it out of contractions. but yeah, i should have at least typed youre in that instance, i screwed the pooch there. 

[rexxar]

Well done for making it work. There are some errors in your schematic. The resistor connecting to pin 7 on each 555 is in the wrong position. You're missing a connection to pin 2 of the lower 555.

D'oh!  It's right on the breadboard, I guess I just can't read.

You could put the photoresistor between the opamp and the 2n2222; when it's dark, there won't be enough current to power the 555. It's not a good solution, but should "work". A perhaps better solution would be to connect it into the timing portion of the first 555 so that it beeps more quickly when it's light, and not at all when it's dark.

That didn't work out too well, so I decided to make the photoresistor part of a voltage divider and feed that into another opamp. This probably isn't the 'correct' way to do it, but it works for me.

Personally, I'd probably try your original solution of using a magnetic float and reed switch or have the whole bottle hanging on a sprung microswitch,  for the sake of zero power usage and simplicity.

Unfortunately, the hobby budget has been rescinded until we can get the car fixed, so I wasn't allowed to order any new parts  . I used what I had to hand, and I think it was a fun project. I got to learn about opamps, charge pumps, and 555s.

Here's my final schematic, I don't think there's any errors this time.  I'm still trying to figure out DIP Trace, but anything is better than my hand-drawn ones...

[daveatol]

Well, it's great that you're getting it to work, and sorry for the bad lead. If it works reliably, then it's the right way to do it

Your schematic is very strange to me, and is certainly not standard. The opamp part with the variable resistor appears to be wired incorrectly with with the parallel 4k7 resistors going between 12V and an assumed/omitted ground. The charge pump is incorrect with the series diode and capacitor.

All the best.

[Psi]

Sparkfun just released a water alarm that maybe useful.
It uses a MCU with arduino code so it would be simple to change it so the alarm sounds when there's no water instead of water present.

https://www.sparkfun.com/products/12069

[SeanB]

That will corrode the electrodes as DC is present. Mutant bunnies anybody? If you are going to do contact probing just use the old fashioned method used in all level controllers of low current AC voltage and detecting the AC voltage across the probe. those work for water and last decades in service, probes and all.

[deth502]

since we keep talking about electrodes and such inside the bottle, if we are going to violate the stated rule of not puncturing the bottle, why not just a single stainless steel tube down to the bottom and detect the level based on the pressure in the tube.

[rexxar]

For maximum ridiculousness we could stick a stainless steel bolt and a thermocouple in the bottle attached to a peltier cooler, and estimate the volume of water based on how long it takes to reach a set temperature.

Bonus: nice cool water for the bunnies on hot summer days.

[strangelovemd12]

That's a bit impractical, Rexxar.  Much better off using separate O2 and H2 reservoirs running into a fuel cell, which powers a small XYZ table.  Set a standard keyboard on the table and it can send a tweet whenever the gas supply is low.  The bunnies simply drink the clean H2O exhaust from the fuel cell.  Don't beat yourself up about it, these simple solutions always seem obvious in retrospect.

[Ryan]

I like the magnet that floats.  Add a reed switch, battery & buzzer, and you're golden.  However,  I have to agree Bunnies need fresh water daily.  How about an automatic watering system that gets them water directly from the faucet.  Those are readily available, get the bunnies fresh water (as long as the hose isn't very long), and a much lazier approach.  However involving electricity, water and bunnies sounds fun.

[Mr Smiley]

Bunny’s are highly intelligent creatures 

Just teach them to press a button next to the water bottle, when it's empty, that latches on a light   

Bunny bonding

 

[rexxar]

Bunny’s are highly intelligent creatures 

Just teach them to press a button next to the water bottle, when it's empty, that latches on a light   

Bunny bonding

 

They already tell me when it's empty. They're expressive enough to communicate with humans, if you've been with them long enough to recognize it.

I like the magnet that floats.  Add a reed switch, battery & buzzer, and you're golden.  However,  I have to agree Bunnies need fresh water daily.  How about an automatic watering system that gets them water directly from the faucet.  Those are readily available, get the bunnies fresh water (as long as the hose isn't very long), and a much lazier approach.  However involving electricity, water and bunnies sounds fun.

I didn't have any magnets or reed switches handy, and I can't buy anything new. So, optical detection built from my limited inventory it is.

[rexxar]

That's a bit impractical, Rexxar.  Much better off using separate O2 and H2 reservoirs running into a fuel cell, which powers a small XYZ table.  Set a standard keyboard on the table and it can send a tweet whenever the gas supply is low.  The bunnies simply drink the clean H2O exhaust from the fuel cell.  Don't beat yourself up about it, these simple solutions always seem obvious in retrospect.

That's a bit inefficient, though. I think a better way would be to have the fuel cell power an arduino which interfaces with an Rpi to do the tweeting.

I wonder if there's an arduino sensor shield to detect water freshness....

[Mr Smiley]

Bunny’s are highly intelligent creatures 

Just teach them to press a button next to the water bottle, when it's empty, that latches on a light   

Bunny bonding

 

They already tell me when it's empty. They're expressive enough to communicate with humans, if you've been with them long enough to recognize it.

Then why bother with all this 

Just listen to your bunnys 

It sounds like a long winded waste of time when your bunnys are already telling you what you want to know. Your just showing mistrust towards your bunnys, and they will not be impressed with that (if you've been around them long enough to notice), resulting in failed bunny bonding 

 

[BillyD]

Bunny’s are highly intelligent creatures 

Just teach them to press a button next to the water bottle, when it's empty, that latches on a light   

Bunny bonding

 

They already tell me when it's empty. They're expressive enough to communicate with humans, if you've been with them long enough to recognize it.

Then why bother with all this 

Just listen to your bunnys 

It sounds like a long winded waste of time when your bunnys are already telling you what you want to know. Your just showing mistrust towards your bunnys, and they will not be impressed with that (if you've been around them long enough to notice), resulting in failed bunny bonding 

 

Well why not. It's entertaining, educational and goes some way towards solving a problem.

The only argument I see against doing this would be if it harmed the animals or environment, or if anyone could think of an even better use of the time and materials he has.

[KerryW]

I didn't have any magnets or reed switches handy, and I can't buy anything new. So, optical detection built from my limited inventory it is.

Dollar Tree sells a "Door alarm" that has a magnet, reed switch, buzzer and other parts for $1.  Not quite 0$, but close.

Kerry

[Mr Smiley]

Poooooor Bunnys 

It will be the first and last time they empty that water bottle,  110db sounder on the last sip 

Just visualize the bunny in the headlights expression with all their hair standing on end and a puddle under their little feet 

Look at the carbon footprint you'll be saving if you just let them tell you themselves, and it'd make them happy that their helping 

 

[rexxar]

Poooooor Bunnys 

It will be the first and last time they empty that water bottle,  110db sounder on the last sip 

Just visualize the bunny in the headlights expression with all their hair standing on end and a puddle under their little feet 

Look at the carbon footprint you'll be saving if you just let them tell you themselves, and it'd make them happy that their helping 

 

The rabbits aren't smart enough to understand that they're 'helping' or that I don't trust them to tell me when they're out of water. Besides, by the time they do notice that the water is empty, it's been like that for a few hours, and I don't want it to get to that point.

If the buzzer scares them, they'll quickly get used to it once they realize it's not a threat. Our heater makes a very loud kaTHUNK when it turns on, and it scared them half to death when we moved in, but now they don't notice it.

Regardless, the point of this whole thing was for me to learn more about electronics. If it turns out I make something that's marginally useful, then great. The point is not how I treat my rabbits-- or rather, how you think I treat my rabbits-- but that I learned something, and got a useful device out of it.

It's very rude and presumptuous of you to condemn me on the treatment of my rabbits when you are 3,500 miles away from me. I treat my rabbits better than many do. I've gone through an inordinate amount of trouble to make sure they can't hurt themselves or the apartment in the entire room I've given them.

I came here for electronics advice, not harassment for your assumptions on how I treat my rabbits.