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 NXP Semiconductors


  • Aquarium Fish Feeder Timer Controller Circuit

  • Created: Nov 25, 2014

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Description

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Summary

This project is a timer controller circuit that effectively controls an automatic fish feeder to feed fishes at a predetermined timing sequence as set by the user. It uses 74HC4060D binary counter, a high speed SI-gate CMOS device that has 14-stage ripple-carry counter/dividers and oscillators with three oscillator terminals, ten buffered outputs and an overriding asynchronous master reset.


As shown in the circuit, the delay in IC 4093 may be adjusted and set with the help of the 1M potentiometer. The first two NAND gates forms the 7 seconds delay timer and the rest of the gates is wired to form a 5.2 seconds delay. The 74HC4060D is designed as the 24 hour timer circuit for the required cycling of the desired time sequences. When the circuit is powered, the 0.1uF capacitors at the inputs of the first and third gates of IC 4093 ground the respective inputs via the 100k resistors. This renders a negative latch across the gate outputs keeping the transistor relay driver to switch OFF. In initiating the circuit , the start button is pressed which reverts the gate latches to positive, switching ON the relays simultaneously. This condition forces pin12 of U2 to become high so that it stays disabled for the time being. After 5 minutes, the capacitor at the third NAND gate (N3), output charges up, forcing the fourth gate (N4) input to go high which restores the latch to negative. Thus, switching off the 5 second relay exactly in the same manner with the second gate relay that switches OFF after the next 2 seconds. This causes the output of N2 and the input of N1 at low state which enables pin 12 of 74HC4060D at low state allowing it to begin its counting until the stipulated 24 hour time is elapsed. When its pin 3 goes high, it causes an automatic triggering and the cycle repeats indefinitely as long as the aquarium feeder circuit is held in the powered state.


Aquarium fish feeder timer controller circuit provides a set of continuous operations based on a predetermined timing sequence using potentiometers as its timing controls. The device will not only be applicable in controlling the automatic fish feeder timer but also used in controlling a fixed timer circuit in any electronic device.