Hex to Binary Converter Circuit

The circuit described here is a hex to binary converter circuit using four, 8-input NAND gate 7430 ICs. The input keyboard switches SW₁ to SW₁₅ are connected in such a manner that the pressing of any switch produces the binary ABCD outputs of the corresponding decoded numbers. When all inputs in a NAND gate are high, it produces a low output, But when any of its input goes low, its output becomes high. Normally, all switches are open, the binary output is 0000. Pressing a switch gives a ‘low input’ to the corresponding NAND gate, and hence the output code becomes a correct binary equivalent of the input hex number.

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