555 Timer

The 555 timer is used as a timer, pulse generator and oscillator, etc. The 555 timer has 3 

modes, namely, monostable, astable and bistable modes. Each have different usage and effects 

on the 555 timer. Here in this example, we will use the 555 timer in astable mode making use 

of it as an oscillator.

Here is a given pin layout of the 555 Timer:

This also has a standard circuit as shown below:

The resistances can be assumed. After having an assumed value for the resistors, the value 


for the capacitance can be computed using the given formula:

where:

Ø  f = frequency of the oscillation

Ø  C = is the capacitance in Farad

Ø  R = Resistance in ohms

Using the computed and assumed values, we can now construct a 555 timer circuit. To 


realize the resulting oscillation, we will connect a LED to the output. This will make the LED 


blink slowly or fast depending on frequency of the oscillation. Higher frequencies will tend to 


make the LED blink at a very fast rate that it will appear as though it did not turn off at all.

As for our final output, here is what we have:

Magnitude Comparator

The Magnitude Comparator is a type of device which compares the two 4 bit binary inputs and determines the output which are the greater than, the equal, and the less than. This device states A>B, A=B, and A<B.

To obtain this experiment, here is a schematic diagram of the experiment.

 And here is the final output of our work:

FULL SUBTRACTOR

 A Subtractor is a Logic that allows the subtracting of binary coded numbers. In this activity we were able to subtract binary coded numbers using the /XOR/ gates, and LED indicators.

Before assembling the circuit we need to know where the IC should be connected, therefore we first need to create the truth table and create a circuit diagram based on the results of the truth table.

After completing the first and second process we need to determine the logic gates diagram of the IC being used in the circuit, and then we simply assemble the circuit by implementing the output based on the circuit diagram and connect the wires to their designated input and output points of every element in the circuit.

Here is the schematic diagram for a 1-bit binary full subtractor:

Now, for our truth table, we obtain this:

Just like our Full Adder, we will have the same 4-bit full subtractor combination:

As for the result, we have this for our final output:

FULL ADDER

In this activity, we will create a full adder which consists of a 4 bit binary number. 


Here is a schematic diagram for a 1-bit binary full-adder.

Now we generate our truth table:

 Afterwards, we will create a diagram for a 4bit full adder combination:

Since we have our full adder combination, we will construct this n our breadboard to obtain our full adder experiment just as seen from the pictures below: