Automatic Fish Feeder - need timer

[hoosier122]

Yes I realize this isn't really a "robot" but I need some help.

I want to make a fish feeder for my aquarium that dispenses 1 tsp (approx) of fish food every 24 hours or so.  I'd like to avoid using a controller.  I have an old alarm clock that I'm considering using.  I'd crack it open find the lead going to the buzzer, connect it to some kind actuator/(might have to use a momentary relay) to move momentarily, which would cause it to open the hopper containing the food, which would dump into the tank.

A few issues I can see...
-  Alarm clocks require you to physically reset them to turn off, then back on.  (Is a relay the best option to reset?)
-  Would an alarm clock be my best option?  It seems convenient because there is already a display.
-  Devise a gravity hopper system with the servo to dispense the correct amount of food.
-  What type of actuator (and control method) would be best for this application?
-  Is an alarm clock the best/cheapest timer for this application?  I just thought it would be neat to use AC...yes I know to be careful.  But obviously I would want this to be plugged into the wall so AC seems to be the answer.

Thanks for your input.  Yes I know there are automatic fish feeders, but I really want a cheap project and this sounds fun.

[Soeren]

Hi,

Yes I realize this isn't really a "robot" but I need some help.

Oh, it IS a robot... A fish feeding robot

I want to make a fish feeder for my aquarium that dispenses 1 tsp (approx) of fish food every 24 hours or so.

What kind of food do you use?
I understand that with automats, some kind of pellets are used mostly and from what I recall about fish food from decades ago when I had an aquarium, the regular stuff is thin flaky stuff that sticks together (and to everything else) when getting even a little wet (or just moist).
This kind would be problematic to use in an automat I think, but I guess things may be different these days, so please describe the kind of food you wanna use.

I'd like to avoid using a controller.  I have an old alarm clock that I'm considering using.  I'd crack it open find the lead going to the buzzer, connect it to some kind actuator/(might have to use a momentary relay) to move momentarily, which would cause it to open the hopper containing the food, which would dump into the tank.

It's relatively easy to use an alarm clock with a bit of (fairly simple) external circuitry.
The signal to the piezo alarm used in most small alarm clocks needs to be rectified etc. but you can get a schematic if you like.

I'm not sure what you mean by "hopper"??

A few issues I can see...
-  Alarm clocks require you to physically reset them to turn off, then back on.  (Is a relay the best option to reset?)

No. Most alarm clocks can be set to a daily alarm and there's no need to reset anything, that's automatically done after some 4..5 minutes tops.

-  Would an alarm clock be my best option?  It seems convenient because there is already a display.

Yes, in the sense that you get a rather accurate timing mechanism for a few bucks in a dime store.

-  Devise a gravity hopper system with the servo to dispense the correct amount of food.

Yes, that will be where you need to spend the most time, depending on the type of food you'd be using.
Perhaps talk to an aquarium shop to see what they'd device, they should know what's available.
I don't see any reason for a servo here.
Still, I'd like your definition of "gravity hopper".

-  What type of actuator (and control method) would be best for this application?

That is hard to say until the details of the mechanical mechanism is thought out.

-  Is an alarm clock the best/cheapest timer for this application?

Yes.

I just thought it would be neat to use AC...yes I know to be careful.  But obviously I would want this to be plugged into the wall so AC seems to be the answer.

Keep the alarm clock on the battery and let it control the AC power (which should be from a low voltage transformer of course, then it's not harmfull if handled correctly).

Thanks for your input.  Yes I know there are automatic fish feeders, but I really want a cheap project and this sounds fun.

It's fun allright and an excellent primer project (plus a learning experience that might lead to more over time).

[SmAsH]

soeren, a "hopper" is a place to hold the food...
by "gravity hopper" he means something like a tube that can hold the food and let gravity pull it down.
eg PAINTBALL!
think of it like a "magazine" for your gun. except its on top and instead of using a spring, gravity does it.

[hoosier122]

soeren, a "hopper" is a place to hold the food...
by "gravity hopper" he means something like a tube that can hold the food and let gravity pull it down.
eg PAINTBALL!
think of it like a "magazine" for your gun. except its on top and instead of using a spring, gravity does it.

Grain bins or silos also use this principal.  It's always good to remember gravity is your friend.

[SmAsH]

of coarse! why did i not use that as an example!
me and my stupid guns floating in my head...

[Soeren]

Hi,

Thanks for the info both of you, I'd never have guessed - my associations with the word "Hopper" goes towards kangaroos or Dennis.
Where's the logic in calling a grain silo a hopper - I bet it don't 

Anyway hoosier122, let me know if you need help on converting a clock or some of the other stuff you wanna do, but please answer my post then as regarding the type of food since it will be getting moist unless a very clever and water tight system is made - the air alone will probably be more than 95% Relative Humidity where the opening will dispense the food.

I think a solenoid would be just the thing to yank 1 or a few times, dispensing a small measured amount each time.

[hoosier122]

Hi,

Thanks for the info both of you, I'd never have guessed - my associations with the word "Hopper" goes towards kangaroos or Dennis.
Where's the logic in calling a grain silo a hopper - I bet it don't 

Anyway hoosier122, let me know if you need help on converting a clock or some of the other stuff you wanna do, but please answer my post then as regarding the type of food since it will be getting moist unless a very clever and water tight system is made - the air alone will probably be more than 95% Relative Humidity where the opening will dispense the food.

I think a solenoid would be just the thing to yank 1 or a few times, dispensing a small measured amount each time.

hopper - "container with narrow opening at bottom," 1277, perhaps from hop (v.) via notion of grain juggling in a mill hopper."

It's flake food.  If the hopper is sealed at the top with a lid and the bottom with a seal on the trapdoor, I don't see any reason why the food would clump.

[Metal Slug 2]

for a dispensing mechanism...take a look at how those 25 cent candy machines work.  they have a rotating thing separated into quarters by sidings which is covered by a metal plate on the top and bottom of it.  the top plate has a hole on it to alow candy to flow through to one of the quarters, when the disk is rotated, the quarter moves over the top middle plate allowing no more candy to go in, on the opposite side there is another hole on the bottom plate, when the quarter has rotated 180 degrees the candy falls down a chute into your hand.  maybe something like this would work...if u had like food pelletes...

[hoosier122]

I'm thinking of having the hopper then at the bottom have some kind of actuator/motor which rotates a plate which has 1 hole in it...approximately 3/4".  When it rotates food will drop while it's open.  When it's closed, it's sealed.

[Metal Slug 2]

yea thats basically what i mean...my descriptive skillz need some work...

[Admin]

You can train your fish to push a button when it's hungry

Ok being more serious . . . it appears the automatic fish feeder companies have all decided to use a microcontroller:
http://saltaquarium.about.com/od/toppicks/tp/TPautofeeders.htm

They all got really smart engineers trying to squeeze every penny, so I'm sure their solution is probably the best.

[Soeren]

Hi,

[...] They all got really smart engineers trying to squeeze every penny, so I'm sure their solution is probably the best.

For a production companhy and for you and me, yes, but if hoosier122 knows nothing about programming controllers, it would be quite a task to learn for just this timer 

[hoosier122]

Hi,

[...] They all got really smart engineers trying to squeeze every penny, so I'm sure their solution is probably the best.

For a production companhy and for you and me, yes, but if hoosier122 knows nothing about programming controllers, it would be quite a task to learn for just this timer 

I'm comfortable in C.  Just saying I didn't really see the use of adding a micro controller because I assume the alarm clock should have something of the sort.  It already has all the software I need programmed in, plus a nice display with buttons.