To study and Verify the BCD come Excess-3 password converter making use of logic gates.

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Learning Objectives

To know the behavior and demonstrate the Implementation the BCD to Excess-3 password converter making use of logic gates.To use knowledge of the basic gates to create truth tables.To develop digital circuit building and troubleshooting skills.To understand an essential elements of TTL reasonable specification or datasheets.

IC Used

For BCD come Excess-3 password converter making use of logic gates:IC NumberIC Name
74LS04Hex Inverting Gates
74LS08Quad 2-input and also Gates
74LS32Quad 2-input OR Gates
74LS86Quad 2-input Exclusive-OR Gates

Circuit Tutorials:


Place the IC on IC Trainer Kit.Connect VCC and also ground to particular pins the IC Trainer Kit.Implement the circuit as shown in the circuit diagram.Connect the inputs to the input switches noted in the IC Trainer Kit.Connect the outputs come the switches the O/P LEDsApply various combinations that inputs according to the fact table and observe the problem of LEDs.Note down the matching output readings for miscellaneous combinations that inputs.Power off Trainer Kit, disconnect all the cable connections and also remove IC's indigenous IC-Base.


Binary Coded Decimal (BCD) password -​ Digital numbers space represented, stored and transmitted as group of binary bits. This group is additionally called as binary code decimals. Weight binary codes room those binary codes which obey the positional load principle. Each place of the number to represent a particular weight. Numerous systems that the password are provided to express the decimal digits 0 with 9. In these codes every decimal digit is stood for by a group of 4 bits.

In this code each decimal number is represented by a 4-bit binary number. BCD is a method to express each of the decimal digits through a binary code. In the BCD, with four bits we can represent sixteen numbers (0000 come 1111). Yet in BCD password only first ten of this are used (0000 come 1001). The staying six password combinations i.e. 1010 come 1111 space invalid in BCD.

Advantages that BCD codes

It is very comparable to decimal system.We should remember binary identical of decimal number 0 to 9 only.

Disadvantages the BCD password

The addition and individually of BCD have different rules. The BCD arithmetic is little more complicated. BCD needs much more number of bits 보다 binary to stand for the decimal number. For this reason BCD is less reliable than binary.

Excess-3 password - The Excess-3 code is also called together XS-3 code. The is non-weighted code used to to express decimal numbers. The Excess-3 password words are derived from the 8421 BCD password words including (0011)2 or (3)10 to each code word in 8421. The excess-3 codes are obtained as adheres to -


BCD come Excess-3 password Converter - Excess-3 binary password is one unweighted self-complementary BCD code. Self-Complementary property method that the 1’s complement of an excess-3 number is the excess-3 code of the 9’s complement of the corresponding decimal number. This home is useful due to the fact that a decimal number have the right to be nines’ additionally (for subtraction) as easily as a binary number can be ones’ complemented; simply by inverting all bits.

As is clear by the name, a BCD digit deserve to be convert to it’s equivalent Excess-3 code by simply adding 3 come it.

Block Diagram



Make the relationships according to the IC pin diagram.The connections have to be tight on trainer kit.The Vcc and ground need to be applied carefully at the specified pin only.

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We have actually learned the Implementation that BCD come Excess-3 password converter making use of logic gates.