Monday 7 October 2013

WEEK 4 

SCHEMATIC DIAGRAM AND FLOW CHART OF PROJECT



Before we start to develop this project. Here we attach the flow chart and schematic diagram for this project : 


BLOCK DIAGRAM

SCHEMATIC DIAGRAM

Explanation For Circuit

As the schematic diagram above, we can see that the VCC will enter the switch first. The switch act as the circuit breaker for the whole circuit. When it is normally open, the power supply will not reach the circuit. But, when it is normally close, the circuit will be running. Then, the current will enter the IC 4060 first .

IC 4060 14-bit counter (Binary counter)

IC 4060 is an Oscillator binary counter of it can be as the frequency divider. The basic frequency of the internal oscillator is determined by the value of the capacitor connected to pin 9 and the resistor at pin 10.  Pin 11 can be used to give clock pulses from an external source. By increasing or decreasing the value of capacitor or resistor, time delay can be changed. Each output goes high after the completion of the timing cycle. For this IC, they have 10 output pin which is pin 1,2,3,4,5,6,7,13,14 and 15. Each output have a difference value of time and from one pin to another, the value is multiple by 2. There are some graph diagram that representing the output of each pin at figure 3.2. The RESET pin must be grounded because pulses are enabled when the RESET, pin 12, is connected LOW and dis-enabled, or inhibited, when RESET is connected HIGH. The VCC pin is at pin 16 and the GND at pin 8.

To know about the time for each output pin, there are some calculation to get the exact value of timer.

Formula to calculate the frequency :

RT = Variable resistor on pin 10 and CT = Capacitor at pin 9.

Formula to calculate the period of pulse :
OUTPUT SIGNAL OF 4060



f = Frequency and t = time

About IC 7411 (AND GATE) 

Next, the output from IC 4060 will enter the IC 7411(AND gate). The 7411 IC is a 3 input and 1 output AND gate. The reason why this IC have been chosen because we want to stabilize the output from 4060 IC same value as the VCC. One of the input were connected to the output of the 4060 IC and the rest were connected to the VCC. Then, the output of 7411 IC connect to the IC 555. The VCC is at pin 14 and GND at pin 7.

Pin of 7411 IC :
PIN CONFIGURATION
A,B and C = input, Y = output
IC 555 (Astable) mode

The output from 7411 IC were connected to the one of the parallel resistor at the Astable 555 IC circuit. The parallel of resistor at the Astable circuit is to match the timing ON of the 4060 output. The Astable circuit must be triggered within the 4060 output still HIGH. So, the resistor value must be accurate to make sure the timer for Astable output triggered on time. When the value of resistor is increase, the time of astable circuit to trigger also will increase. Pin 4 and 8 were connected to the Vcc while pin 1 is to the GND. Pin 6 and 2 should connected together than connect to the R3 and C2. The output of Astable circuit is connected to the pin 2 at monostable circuit.

Formula for calculate HIGH time :

Time HIGH (1) = 0.693 x ( R5 + R3 ) x C2

Formula to calculate LOW time :

Time LOW (0) = 0.693 x R3 x C2

Formula to calculate the frequency :

Frequency = 1.44 / (( R5 + R3 + R3 ) x C2

Output wave :
OUTPUT SIGNAL

IC 555 (Monostable) mode

This is the last circuit that function as the timer for motor to running. The duration of motor to running is depends on the resistor (R4) and capacitor (C3) that connected to pin 7 and 8. This monostable circuit must be receive the continuous power supply. But, it will function when the power supply is cut-off for a while. Then, the output will goes HIGH. So, the output from Astable circuit will steadily HIGH and then it will LOW for a while. At that time, the monostable will start function means the motor will running. When the value of R4 and C3 increase, the duration of motor to running will increase. Pin 4 and pin 8 were connected to the VCC while pin 1 is connected to GND.

Formula to calculate the timer :

Time HIGH = 1.1 x R4 x C3

The output waveform :
OUTPUT SIGNAL








1 comment:

  1. Thank you for this informative blog.I want to design the automatic fish feeder system.But there is one question arises after following the above design that WHERE SHOULD WE KEEP THE FISH FOOD? n FROM WHERE WE CAN GET THAT FOOD OUT? Please help us in this regard as early as possible.Thank you :-)

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