project ideas needed - automated fish feeder

[Brett]

OK, I have a bit over a week before I go on holidays for a week.  I have some fish that "need" feeding while I'm away - Plan A is to ignore them (apparently fish can live for up weeks without food, the internet tells me so), Plan B is to use a fish feeder block in the tank. Then Plan C or D came along...... I was prompted by my wife to think about an automatic fish feeder, since the fish in question eat shrimp pellets - so the thought of a rapid prototype of a fish feeder might be an interesting way to spend a few nights over the next week rather than going and buying a commercial one for $50 (that was Plan C I guess).  So, anyone previously solved this problem? 

 

I was thinking about the following couple of approaches.

 

1) linear movement releasing measured cells of food into the tank. Was thinking a moving bottom-less group of cells that then moved over an open aperture. movement driven by a rack-and-pinion arrangement, rack on the holding cells, rotation perhaps from a modded full-rotation servo - none of which I poses :)

 

2) rotational movement over open aperture - same basic approach with a circular hopper with a set number of cells directly mounted to a servo, moving over an open "wedge" aperture.

 

3) some form of "plunger" design (I imagine this in a horizontal configuration) that pushes a quantity of pellets out the end of a tube or something, and the pellets sit in a hopper above the plunger. A full rotation servo and arm with wire pushrod could be used for the movement - but I'd be concerned that the "gnarly-ness" of the pellets may cause binding (so the failsafe plan is that Plan A becomes live in absentia). 

 

Other thoughts/directions/suggestions?  I'm certainly not going to spend a huge amount of time/effort on this, in fact the more I think about it the more Plan A comes to the fore :)

 

 

[Brendan Humphreys]

 

2) rotational movement over open aperture - same basic approach with a circular hopper with a set number of cells directly mounted to a servo, moving over an open "wedge" aperture.

Instead of a servo-driven mechanism you could use the hour-hand drive of a clock mechanism. With the hopper attached to the hour hand, and a hole at midnight...

 

[Keith Franks]

I agree with the hour hand mechanism, but depending on how long you'll be gone for, you might only need a long vertical pipe around the same size as the pellet (slightly larger) to alleviate most jam issues (especially shrimp jam). 

However, you prolly don't want the hole to be (at least partially) open for a whole hour..... 

On Tue, May 21, 2013 at 1:25 PM, Brendan Humphreys <brendan....@gmail.com> wrote:

 

2) rotational movement over open aperture - same basic approach with a circular hopper with a set number of cells directly mounted to a servo, moving over an open "wedge" aperture.

Instead of a servo-driven mechanism you could use the hour-hand drive of a clock mechanism. With the hopper attached to the hour hand, and a hole at midnight...

 

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[Matt Joyce]

A tube with two servos, upper and lower.

Upper servos open a gate to drop pellets to lower servo gate, then closes.

Lower servo open to drop pellets, then closes.

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[Keith Franks]

+1 to what Matt said.

[Neill Wainwright]

Hi Brett, 

Funny timing, I was about to take on the same project for my aquarium! 

Perhaps a collaborative effort may be in order ;-) 

Cheers - Neill 

Sent from mobile device 

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[Matt Joyce]

Another solution would be an Archimedes screw in a tube.

[Kris]

I think I've seen one made out of Lego (a fish feeder not an Archimedes screw).

Just on plan a, according to my mother in law, your fish can be left for a week but only if they are used to being feed sparsely already.
I would guess a metabolism issue behind that advice

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[Madox]

Assuming swivel gates, how can the top one close when all the pellets have hit the bottom gate and now obstructing the top gate too? :)

Sliding might work but again prone to jamming :)  

PROTOTYPE!

[Brett]

Agreed Madox, the top-gate thingy was what had made me discount it. Once the lower part of the tube becomes "full", you can't effectively close it without having space in the tube/system and fighting against the flow from above - and that's why I had thought the open aperture approach would be more effective

[Patrick Barnes]

I know this is heresy... but;
http://www.crazysales.com.au/automatic-fish-feeder-with-anti-jamming-ff-03.html

Alternatively, how about a scoop attached to a clock's hour-hand, that
once-per-12-hours dips into a reservoir of pellets and pushes some up
and over a lip, dropping them into the tank?

Or you could put some small fish in a sub-tank, and train them to
interrupt a photo-beam at regular intervals, energising a solenoid that
drops food into the main tank. :-P (And then a sub-sub-tank to make sure
the sub-tank's fish get fed, maybe filled with well-trained snails?)

-Patrick

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[Terry Dawson]

Or ask a neighbour to feed your fish for you while they're checking your mail.

Terry

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[Brett]

there's always one, isn't there.... how does that lead to lost hours in thinking about this, an increase in tools that would facilitate "rapid prototyping", and (finally!) justification for having yet another microcontroller in the house? :p

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[Brett]

The "commercial" option I was looking at was $50, now you've set a new benchmark.  And yes, totally, I get the benefit of doing this, but it's not "customised" like I am sure you would agree, we all need.  Anyway, Plan A is still looking the winner, heck it's only a week :)

[Madox]

http://www.blogouillage.net/2013/05/diy-cat-feeder-v20.html?m=1

From HaD

[Patrick Barnes]

Sure.

My second suggestion was serious - a scoop that lifts some pellets up
shouldn't jam too easily, and the scoop width could be set to dispense
an appropriate amount each time.

-Patrick

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[Terry Dawson]

On Wed, May 22, 2013 at 4:11 PM, Brett <brett...@hotmail.com> wrote:

there's always one, isn't there.... how does that lead to lost hours in thinking about this, an increase in tools that would facilitate "rapid prototyping", and (finally!) justification for having yet another microcontroller in the house? :p

That depends very much on the neighbour :)

Terry

 

[Gav]

Ok, here's my solution. A circular plate directly above the tank, with its circumference scattered with fish food. Above is a heavy Foucault pendulum that slowly precesses, knocking new bits of food into the tank as it goes :-) the downside is that the easiest way to tune speed of dispensing is to adjust your house's lattitude...

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