To research and Verify the BCD to Excess-3 code converter making use of logic gates.

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Learning Objectives

To understand the actions and demonstrate the Implementation of BCD to Excess-3 code converter using logic entrances.To apply expertise of the standard entrances to produce truth tables.To construct digital circuit building and troubleshooting skills.To understand also key elements of TTL logic specification or datasheets.

IC Used

For BCD to Excess-3 code converter using logic gates:IC NumberIC Name
74LS04Hex Inverting Gates
74LS08Quad 2-input AND 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 corresponding pins of IC Trainer Kit.Implement the circuit as displayed in the circuit diagram.Connect the inputs to the input switches provided in the IC Trainer Kit.Connect the outputs to the switches of O/P LEDsApply assorted combicountries of inputs according to the truth table and observe the problem of LEDs.Keep in mind down the matching output readings for various combicountries of inputs.Power Off Trainer Kit, disattach all the wire relationships and remove IC's from IC-Base.


Binary Coded Decimal (BCD) Code -​ Digital numbers are stood for, stored and transmitted as team of binary bits. This group is also referred to as as binary code decimals. Weighted binary codes are those binary codes which obey the positional weight principle. Each position of the number represents a specific weight. Several systems of the codes are supplied to express the decimal digits 0 with 9. In these codes each decimal digit is represented by a group of four bits.

In this code each decimal digit is stood for by a 4-little binary number. BCD is a way to express each of the decimal digits via a binary code. In the BCD, with 4 bits we have the right to recurrent sixteen numbers (0000 to 1111). But in BCD code just first ten of these are used (0000 to 1001). The staying six code combinations i.e. 1010 to 1111 are invalid in BCD.

Advantperiods of BCD Codes

It is exceptionally similar to decimal system.We must remember binary identical of decimal numbers 0 to 9 only.

Disbenefits of BCD Codes

The addition and subtraction of BCD have various rules. The BCD arithmetic is little bit more complex. BCD requirements more number of bits than binary to represent the decimal number. So BCD is less reliable than binary.

Excess-3 Code - The Excess-3 code is additionally referred to as as XS-3 code. It is non-weighted code provided to express decimal numbers. The Excess-3 code words are acquired from the 8421 BCD code words including (0011)2 or (3)10 to each code word in 8421. The excess-3 codes are acquired as complies with -


BCD to Excess-3 Code Converter - Excess-3 binary code is an unweighted self-complementary BCD code. Self-Complementary home suggests that the 1’s match of an excess-3 number is the excess-3 code of the 9’s match of the corresponding decimal number. This residential property is advantageous given that a decimal number can be nines’ complemented (for subtraction) as easily as a binary number have the right to be ones’ complemented; just by inverting all bits.

As is clear by the name, a BCD digit have the right to be converted to it’s equivalent Excess-3 code by ssuggest including 3 to it.

Block Diagram



Make the relations according to the IC pin diagram.The relations need to be tight on trainer kit.The Vcc and ground should be applied very closely at the specified pin only.

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We have learned the Implementation of BCD to Excess-3 code converter using logic gateways.