lukman arif wijaya: DIY Centrifugal Fish Autofeeder

12 Mei 2009

DIY Centrifugal Fish Autofeeder

First Auto Feeder Circuit for Koi

This easy as well as cheap device is mainly intended for your ease to leave your fish auto fed. You need no longer worry that your fish would get starved as this automatic fish feeder device would replace your job. This device will expel pellets by quantity as well as time intervals as you set. Besides, making this circuit seems to be a bit entertaining as you are insisted to make it yourself and so that it would then revive your creativity. Don’t worry, it works!

This device comprises of 2 sections, electronics and mechanics:

1) Electronics Section:

The main role of this section functions as a timer (few hour intervals) with progress indicator (LEDs) and the mutual action of the relay-capacitor in series functioning to expel pellet in a quantity.

Picture 1: Circuit Block

Picture 2: Schematic Diagram

How It Works:

The circuit uses regular timer (IC 555) sending pulse to 2 counters in series of CMOS 4017. The output pin from the last counter is then fed to the capacitor-relay in series (remember that a relay owns its wiring resistance) which then results the relay in contact for some time to turn on mechanics section. After the capacitor is about to be fully loaded, the relay shuts off. From here we could figure out that the bigger the capacity of the capacitor, the longer the relay connects which then causes the motor to rotate while expelling pellets centrifugally. The shunt resistor functions to unload the capacitor load slightly so that it is then ready to be loaded for the next cycle.

Time interval if the IC 555 keeps following the formula:

T(555) = 1,1 x R x C

For short, if we set the timer T = 3 minutes, the both counters will multiply the time to be 10 x 10 = 100 times. So the total time intervals would be T = 3 minutes x 10 x 10 = 300 minutes = 5 hours. To change the time intervals is simply by changing/turning R-Var and pellet quantity is by changing C-Var size.

2) Mechanics section

All you need for this section are small 12V DC motor, the ring rail, transmission cable, a cone-shaped plastic bottle (as shown on the pic), some glue/alteco, a coin (about to reach the bottleneck diameter, cutter, match, solder, etc. Please try making yourself convenient to develop your own creativity. You can increase your bottle capacity by using a larger/much larger one but consequently you've got to change the motor, plate/coin, etc accordingly to keep up with your new construction. Do not change the electronics section if not necessary.