Got a fish tank, you also love your fish, but you are kind of person who does not like to do anything for the fish except to watch them or you don’t actually have time to feed then (highly unlikely) or you are a regular traveler and often go for business trips? And top of that a BIG DIY geek. Then this is the perfect instructable for you.

Here we are going to make a Fish Feeder. This is quite simple design works quite well and highly reliable. The basic tools and materials can be easily found in every house, like bottles, a metal rod, and A DIY geek will also have some basic electronics stuff like power supply, transistors, resistors, arduino etc

Step 1: Gather Your Stuff.

• Bottles of two different sizes
• A metal rod
• A motor
• Some Wires
• A transistor
• Some Hot Glue
• A Few Rubber Bands
• Soldering iron
• A Few Ice Cream Sticks
• PCB board
• A 5 Or 12 Volt Relay
• A Power Supply.
• Some Fish Food
• Some Flex Plastic Pipe
• And Few Basic Tools.

Step 2: The Circuit

We cannot directly connect the
relay or the motor with the Arduino. In my case, the simple reason is that, my motor works on 12-24 volts and the relay I am using also works on 12+ volts. Even if you have a relay that works on 5 volts, It is highly recommend you to use an external switching circuit, as the relay or the motor will drain a lot of current from the Arduino and this is not good, The high current that is been drawn can permanently damage your Arduino.

Hence, we need to design and use an external circuit, which will help in switching the motor. The above diagram shows the basic switching circuit that I have used in this Instructable.

The circuit is relatively simple to make and is quite reliable too.

Step 3: The Aurdiuno

Now we need to get the Arduino into action. Here I have used a basic program available in the Arduino program known as ‘Blink’

You can load, the program by going to the File menu and then navigating to examples, followed by basic and blink.

Once the program is loaded, you need to do some small changes in the program.

The first thing is that you require to change is the pinmode . The pin number in the program should be given as 13, you need to change it to 12 everywhere in the program. Though I have used Pin 13 in this Instructable.

The second thing to do is that, you need to change is the timing of the program ie how much time will it allow the motor to run and then how much time should it remain ideal.

So basically, you need to change the delay high time to the point where the motor is allowed to rotate the inner food tank till the point where the fishes are fed adequately and should stop at a position where the fish food from the feeder is not falling ie the open end of the food tank is facing in the upward direction.

The other ideal time, is the time where the motor is not running. Simply it will be time interval after which the motor will start running again. So if you want to feed the fish after every 4 hours you need to change the delay time.

Step 4: The Feeder Mechanism

The feeder Mechanism consists of two bottles (one larger bottle serves as the feeder frame and the other smaller bottle as the food tank which will be placed inside the larger bottle), a motor and a drive rod.

You need to make a hole through the bottom of the larger bottle so that the motor fits through the hole as shown in the picture. Also make a hole on the bottle cap slightly larger than the drive rod so that the rod can rotate freely.

Similarly make holes through the bottle cap and the bottom in such a way that the rod just fits the bottle and the rod does not rotate freely without the smaller inner bottle.

Make a fer holes in the center region of the smaller bottle in a small region as shown in the figure.

Now take the larger bottle and cut it from the center. take the rod through the larger bottles cap and then through the smaller bottle and secure it tightly with the motor with small piece of the flex tube. also cut a large hole on the bottle as shown in the picture.

Place few ice cream sticks around the larger bottle and secure it with fer rubber bands. this will give the bottle support.