13-05-2011, 04:59 PM
Name– study of full adder logic circuit.
Aim – to study the working of full adder for three binary digits addition.
Apparatus – IC 7408, IC 7486, IC 7432, circuit board, LEDs, power supply +5V DC, connecting wires, soldering iron, cutter etc.
Circuit diagram –
[attachment=13833]
[attachment=13834]
Procedure –
1) Solder the circuit of full adder, on the given board.
2) Connect respective pins of each gate to the corresponding pins of other gate.
3) Connect the outputs ‘sum’ and ‘carry’ to two LEDs.
4) Apply different combinations of inputs as per truth table and note down the corresponding change in the outputs of the circuit.
5) Tabulate the readings.
Brief theory –
Possible input combinations – full adder can add three binary digits at a time. It is actually the extension of half adder circuit. It has three inputs A, B, C with two outputs CARRY and SUM. Note that when two half adders are cascaded along with an OR gate, we get full adder.
The logic equations of carry and sum outputs are given below
[attachment=13835]
[attachment=13836]
