I am having problems with the following question:

Using two 3-8 decoders, design a circuit to perform the following function.

F(A,B,C,D) = ∑(0,4,6,14)

Is anyone able to show me what to do here. I am finding decoders quite a tricky topic. Please help. Can anyone also explain how to solve the problem?

 

A decoder like a 74LS137 simply uses the three bit input to enable one of eight outputs. Get the data sheet for one to see how it's done.

 

The question I have posted asks for 4 inputs. How is this done if a decoder only has 3 inputs?

 

Possibly one decoder can use three inputs, and the fourth plus two others can feed the second one.

 

you must search the topic DECODER EXPANSION....decoder expansion is all about how to construct 4-16 decoder from 3-8 decoder.....after reading this you will be aware of the intricacies by yourself....

 

Most decoders/encoders have a disable pin, that is the key.