Evil Kitty Low Food Warning Device for Human Servants

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Our two evil kitties get really mad when their food runs out. They have gentle ways to remind us of our failings (rotten cream-sucking cats). To prevent such 'reminders' I made a device to indicate when the food level starts to run low.

We have a cat food dispenser that stores the food vertically in a silo type tower with an opening at the bottom where the food spills out into a small dish. We keep this tower in a closet on the floor under a shelf. The light in the closet does not illuminate the tower enough to see the food level. This device lights up when the food level runs low.

The device is mounted at the top of the tower. Inside the tower, a golf ball attached to the device with a piece of string monitors the food level.

When the ball lowers to what the kitties refer to as dangerously low food level (anything but full), the string goes taught causing a light to indicate the food level is unacceptably low. When a human servant (i.e. me or my wife) see the light we know we must obey the kitty rulers and refill the food tower immediately.

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Step 1: Site inspection

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We cannot see if the food level is low due to the shelf blocking the closet light. I know what you are thinking, just move the food tower somewhere else or install another light to illuminate this are under the shelf. If only it was that simple. We offered this solution to the kitty committee and both ideas were rejected. Anyway, its more fun trying to work something out - excuse to publish instructable. Picture shows closet with food tower in center.

ahallock-1 says: Mar 12, 2011. 1:35 AM

And what happens when the batteries die and you didn't notice? :P

n8man says: Jul 22, 2008. 9:53 AM

! think you forgot the evil kitty high pitched beeping noise that forces you to refill it.

ReCreate in reply to n8manApr 22, 2009. 8:37 PM

yes it could be done with a 555 and a speaker(get the 555 to go on and of fast enough to make a noise in the speaker)

Dream Dragon in reply to ReCreateOct 15, 2009. 1:03 PM

or one of those annoying musical greetings cards. They have a"pull" switch already built in.

ReCreate in reply to Dream DragonOct 15, 2009. 3:21 PM

Yeah they do.

Dream Dragon in reply to Dream DragonOct 15, 2009. 1:05 PM

but then, my cat would have ripped the bottom corner of the food bag open.

"Please explain why I should waste my time with that silly littlefeeder thing when there's a whole sack of cat food just here that I caneat whenever I want?"

trailleadr in reply to Dream DragonSep 13, 2010. 6:27 AM

That's a very assertive cat!

Wyle_E says: Sep 9, 2008. 6:57 PM

You didn't mention a ballast resistor for the LED. If you used a 'constant current' LED, you don't need one, but a typical red LED has a forward drop of 1.8 volts, and will overheat on 3 volts unless you put a resistor in series. There is a small range of overvoltage in which the LED gets just hot enough to limit the current, but doesn't burn out, Yours seems to be operating in that range. The ballast resistor value is easy to calculate if you know the operating current of your LED. Radio Shack LEDs have this on the back of the package. To get the resistance, subtract the LED forward voltage from the supply voltage and divide the result by the LED current. In this case, assuming 15 milliamps for the operating current, (3.0 - 1.8) / 0.015 = 80 ohms. The nearest standard value is 82 ohms, close enough. My cats usually inform me that their food dispenser is empty by jumping into my lap and stomping on a part of my anatomy that is not adapted to such treatment.

haruspex in reply to Wyle_EOct 15, 2009. 7:22 AM

For a fun and in-depth look at which LEDs need resistors, check out:
Some thoughts on throwies by Evil Mad Scientist Laboratories.

knexfan9182 in reply to Wyle_ESep 10, 2008. 2:10 PM

ohh mine bites me :(

Brad_Smith (author) in reply to Wyle_ESep 9, 2008. 8:18 PM

Thanks for the technical info. The radio shack people were my consultants but may have missed selling me a resistor. My light seems to last quite a while but also seems to use up the batteries faster than it should. I will look into improving this by getting a resistor. Back to the shack...

withnall says: Mar 26, 2009. 8:56 AM

Um, kitties kin jump upz! Just put the fud 'n water dispensers at your eye level and give them a few places to jump to get up. You can then see easily if they need filling and bonus-they exercise!!

EnigmaMax says: Sep 11, 2008. 8:15 PM

...interesting.

Kosmos says: Apr 3, 2008. 4:46 PM

Do you think this could be adapted to work on a 2 litre water bottle....

my 3 feline overlordessess get very mad when their water bottle empties and I have a disability which prevents me from bending down far enough to check the water level.

if the only part of the project that goes inside the container is a piece of fishing line and a ball, then there should be no electrocution risk. I'd just need a ball that acts as a float? right?? but then it might not be heavy enough to trigger the switch?

Any ideas ? My HRF's are hard to please (HRF = Her/His Royal Furriness)

Great Idea by the way :)

knexsuperbuilderfreak in reply to KosmosJul 22, 2008. 8:42 AM

u can puta peice of foam and the Low Food Warning Device

Brad_Smith (author) in reply to KosmosApr 3, 2008. 8:16 PM

I guess you have one of those bases where a bottle is held upside down and it dispenses into a bowl. Making any kind of hold in the bottle would upset the air pressure that holds the water back and would let it all out. Maybe something like a floating object that you could stuff inside the bottle. You could then look for this colored floating object instead of trying to identify what level is the clear water. In your case the small opening of a 2-liter bottle presents a challenge. One idea could be a dozen or so small colored floating balls. The would spreadout over the surface of the water level. If you used just the right amout they could form a single layer the diameter of the bottle. This would be easier to see. Maybe someone out there can suggest another idea. One concern about this is mold/bacteria growing on the components that come in contact with the water. I used fishing line instead of string and clean it regularly. I also throughly washed the golf ball. You may want to keep this in mind when planning your solution. Good luck.

bmlbytes in reply to Brad_SmithSep 11, 2008. 11:44 AM

Yes, as brad said, any hole in the bottle would ruin it and make water overflow the little bowl below. One suggestion would be to point a laser through the 'flatter' parts of the bottle (not where the neck of the bottle is and not the handle. This would make the laser spread out when it is pointing through the water, when it is not pointing through the water, and is only pointing through plastic, it should make a better 'beam'. Point this 'beam' at a photo resister which is connected to a transister to close a circuit when the 'beam' hits the photo resister. I know it's complicated, but its the only thing i can think of right now.

ReCreate in reply to bmlbytesApr 22, 2009. 10:00 PM

photo transistor,or photo cells(that is what it is called at radioshack)

bmlbytes in reply to bmlbytesSep 11, 2008. 11:45 AM

Also, the laser should be near the bottom of the bottle (where it would be needed to be refilled) and not in one of the 'ribs' of the bottle

bmlbytes in reply to bmlbytesSep 11, 2008. 11:54 AM

Here is a pic of my idea

Kosmos in reply to bmlbytesSep 12, 2008. 6:56 PM

thanks for that :) partner is electronics engineer and could build that for me

deshane says: Mar 2, 2008. 5:23 PM

ingenious.. even if I can't spell it correctly! My kitty overlords (four of them share me in my small apartment) hate me for not doing this because KO #1 will get overweight again if I let them free-range on the food when I'm not around. I will have to hide this Instructable from them!

Brad_Smith (author) in reply to deshaneMar 28, 2008. 4:59 PM

KO#1 - just love the abbreviation.

MoonDancerChick says: Mar 27, 2008. 9:35 PM

Great! We are lucky that our kittys just love us to death so we give them more food. I am sending this to my Mother in law, she has evil kitties that would love this device.

Brad_Smith (author) in reply to MoonDancerChickMar 28, 2008. 4:58 PM

Do not mistake 'love' for demanding obedience. She should also obey the kitty over-lords.

kikkoman7347 says: Jan 27, 2008. 4:57 PM

Very good idea! While you still must serve the Evil Kittens, you can do so on your own terms. Way too "stick it to the man - er, Furballs!"

Brad_Smith (author) in reply to kikkoman7347Mar 28, 2008. 4:57 PM

I love your 'stick it to the man err furballs' wording. Too funny.

Brad_Smith (author) in reply to kikkoman7347Jan 27, 2008. 6:37 PM

We must obey the kitty-overlords

jongscx says: Dec 21, 2007. 7:18 AM

wow... those are expensive parts...

Doctor What in reply to jongscxDec 21, 2007. 6:43 PM

Just rip apart old toys until you find the parts you need. Why pay 20 cents for a resistor when you can find a million of them in a barbie boom box??? ^{I steal mine from my sister.}

tyeo098 in reply to Doctor WhatDec 21, 2007. 7:18 PM

Use a 99c buzzer instead, that way, youll hear it before you see it, and risk less of the... cat-piss beds

Brad_Smith (author) in reply to jongscxDec 21, 2007. 6:02 PM

I spoke with the kittys. They say nothing is too good for them. The official kitty orders are to spare no expense to keep them happy - well as happy as a cat can get. But seriously, cost of this project is less than compared to a few trips to the dry-cleaner with a comforter in hand. Thats what we were previously facing when the food ran out. Lemme tell you these are some angry vindictive cats! Also keep in mind I had plenty of left over materials to use on other projects so not all the expense was just for this one project. Plus I got my first soldering gun and a new tool is always welcome. Thanks for your comments.

Trinity in reply to jongscxDec 21, 2007. 10:20 AM

then dont make it

jongscx in reply to TrinityDec 21, 2007. 1:25 PM

It was more of a comment on how much Radio-hut price-jacks, but okay...

thomasedisonjr says: Dec 21, 2007. 6:24 AM

Brilliant! It could also be designed to activate some kind of a voice warning, like "FEED ME!".

Brad_Smith (author) in reply to thomasedisonjrDec 21, 2007. 5:50 PM

Thanks for your comments. I did consider an audible alarm but realized the kittys eat at all hours. I would not want a buzzer going off at 3:AM even though I am a mere servant. Keep in mind, there is still food in the tower when the light turns on. It's primarily to get the humans attn to refill the food tower before it runs out.