Hello,

I am going away soon and need to make a device to feed my fish once a day while I am away.

I have experimented and tested...I am close to finishing but now I am stuck. The image attached is what I have on my breadboard, my own design. This is how it works.

The 555 pulses to the 4040 binary counter. On the 4040 IC, there are four outputs that all light up together at a certain time interval, when all the outputs are high, it triggers the AND gate to give a high output and the gate trigger a relay, which will turn a geared motor. The motor is what will feed the fish. (There has got to be an easier way!)

When I change the value of the 555 cap to a high value, the time it takes to turn on the relay is longer (can be calculated).

This is the problem, the circuit will trigger every 24 hours, but then the relay will stay on for a very long time also. I need the relay to have a short 1 sec. pulse evry 24 hours, I need a time delay! I have tried some things and just can't get it to work.

An option would be to pull the reset high after the relay is on for one second, this would reset the timing and it would start over.

Could someone please guide me or help me out with letting the motor only stay on for 1 second, then reseting the circuit, I think this is the easiest way.

I really don't want my fish to die from starvation :cry:

Would really appreciate some help,

thanks

George L.

Attached Files

fish_feeder.doc (40.5 KB, 59 views)

 

I would probably use another 555 timer set up in a one-shot (monostable) configuration with a time constant of 1 second to drive the motor. At that point, the 4-input AND gate (4082) would be changed to a 4-input NAND gate (4012). (or just invert the 4028's output). The output of the NAND gate will go low and trigger the one-shot when your specific count is reached, turning on the motor for one second. Don't forget to add a diode across the relay coil (anode to ground) to protect to the 555's output circuits.
JB

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You want to divide down to 1 pulse every 24 hours, that is 86,400 seconds. The 4040 only divides by 4096 maximum, so there is no point in using a gate to decode a lower number. The 24 hour period is 11.5x10^-6 Hz; multiplying that by 4096 gives .04714 Hz for the clock frequency. That is a period of 21 seconds which is just barely doable using a 555. In the circuit below you should use tantalum caps because they are lower leakage than aluminium.

Attached Images

fish_feeder.png (8.4 KB, 305 views)

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WOW, thank you so much!

I am almost finished breadboarding your circuit, my fish will live after all!

Your way is much easier, I really appreciate your help.

What program did you use to draw that up, it looks good.

Thanks,

George L.

 

I use Autosketch, make my own symbols.

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if they are small and has lot of vegitation and aeration, they can survive a week without food.

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Incredible !ndia

www.flickr.com/photos/_akg/

"Give a man a fish, and he will eat for a day. Teach that man to fish, and he will eat for a lifetime."

 

Don't forget to connect pin 1 to ground on the second 555 IC (to the right). The drawing doesn't show it ...

What if he's gone a month?

JB

__________________
Nothing is impossible for the man who doesn't have to do it himself - Weiler's Law

 

i know my dad once found a pond in a house he was working on which hadnt been looked after for over a year. it has some of the largest fish he has ever seen! this is because in such a large pond (it was very big) there is lots of algae and creatures that the fish can eat to survive.

 

nature will take care :lol:

__________________
Gods own Country
Incredible !ndia

www.flickr.com/photos/_akg/

"Give a man a fish, and he will eat for a day. Teach that man to fish, and he will eat for a lifetime."