How to convert a decoder to a demultiplexer
The answer is one Google Search away.
Let me google that for you
Anyway, the answer is “using enable signal”. The select lines of demux goes to input bits of decoder. The input pin of demux goes to ‘enable pin of decoder’. when enable=0, all decoder outputs are zero. If enable is 1, only decoder’s output corresponding to input bits will be 1, all other outputs will be in 0. Essentially, decoder will have same truth table as demux.
