Hey there

I am knew to electronic's and this website so this question might sound super dumb. I have to arrange several 74151 1-of-8 multiplevers to form a 1-of-64 mulitplexer. Now assuming the word several means a few, i think i have to have 8 1-of8 multiplexers, and connect each output to a 9th 74151 multiplexer, to effectively give me a 1-of-64. is this correct. A fellow IT mate disagree's and thinks its impossible to do with a 74151 rather a 74157, but this is what the quesiton asks.

Thanks very much

Kieran

 

Do you have a schematic?

 

Na mate i wish i did but all it says is "Arrange several 74151 1-of-8 multiplexers to form a 1-of64 multiplexer". So all i can think of is to have 8 and join all the output's to another 1-of-8 to theoreticall make a 1-of-64 multiplexer

 

Not quite. Each '151 has three selection lines and an enable. That's a big hint.

 

Thanks beenthere. I think i understand what your saying, but i don't know how to implement it. I will still need 8 multiplexers to get 64, but i don't think i will need the 9th. If place an inverter on E3 of my circuit and leave E1 and E2 as the appear standard (if that makes sense). And have all of them connected to A0, A1, and A2, and change me E's to suit (1st '151' has E1 and E2, second '151' had E2 and E3 etc). Then i should have a 1-64 multiplexer. Is this right or am i just confusing people?

 

You will use the 9th to control the 8 that will give you the 64 inputs.

You need 1 to control the 8.

 

You need 1 to control the 8.

It might be better to say "use one to pass the output of the active '151".

However it is stated, the OP needs to make a schematic that at least shows the enabling circuitry.

 

Agreed on both points. The wording and the need for a schematic.

 

Choice thanks guys. Well i will attempt to draw a circuit/schematic and get back you. Hopefully it will make sense. I think i have a good idea now. Keep up the good work