Another dumb questions

[growler]

Re: Another dumb questions

I have an interesting observation on boolean logic.
I was in a class in the late 80's when the instructor looks around and say's " some of you don't look very young, so you should remember boolean, the new math, base 2". I had been in other classes over the years but no one had ever made the connection before. Sure we remembered the new math from the early 60's. When we were small no one told us what the new math was for so we all promptly forgot about it for over 25 years.

 

[rattus]

Re: Another dumb questions

Sam, you have shown two XORs in cascade, and logically this is correct, but how about the truth table? It can be built by inspection of switches A, B, and C.
Rattus

 

[physis]

Re: Another dumb questions

The truth table already shows all possible states of the switches and load.

 

[marinesgt0411]

Re: Another dumb questions

Yes please put s4 at each switch locations just make it clear as to which lights you want to control with which switch nothing I hate more when wireing a two or more gang switched is trying to figure out what the engineer or costumer wants

 

[rattus]

Re: Another dumb questions

Sam, I am trying to make you write:

ABC + AB'C' + A'BC + A'B'C'

 

[physis]

Re: Another dumb questions

You want an expression to define the n-ary operator? I thought that was only used for text book exercises.

A'BC' + AB'C' + ABC + AB'C

You could say this too and every state is defined.

{A≠B}≠C

My preference is the truth table. It's all right there. Easy to read and find what your after.

 

[rattus]

Re: Another dumb questions

True Sam,

The truth table and logical expression carry the same information. I like the Boolean expression because it uses less space and relates one to one with the switch positions.

Then again, how many electricians need to know this stuff? And, even if they do know it, do they use it? I'll bet you don't.

Rattus

 

[physis]

Re: Another dumb questions

I was thinking after I posted that I'm severely biased from using too many semiconductor data manuals.

I used to use the gate symbols to solve the logic a lot because it was either already a circuit or it was going to be. It's easier to plan what gate packages to use too. A lot of times you can use extra gates from a couple chips to make a different operation and be able to eliminate a chip.


I suppose half the input states is all you need. It's not actually hard to read.