simple circuit exam questions

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english bob

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I took the Florida limited energy exam and had a problem with the "simple" lighting circiut questions, the one's that asks what light will go on or off if such a button is pushed? As I was short on time in the exam I did not really spend I lot of time trying to solve the answers. Are there any practice questions out there on these circuits, I know they are simple but I just want to see some again!!!?
 
english bob said:
I took the Florida limited energy exam and had a problem with the "simple" lighting circiut questions, the one's that asks what light will go on or off if such a button is pushed? As I was short on time in the exam I did not really spend I lot of time trying to solve the answers. Are there any practice questions out there on these circuits, I know they are simple but I just want to see some again!!!?
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Try the basic electricity practice exam on this site

http://www.electricaltrainingservices.com/online_assessment_tests.php
 
080620-1942 EST

english bob:

If you exclude circuits with relays that feed back into the switching logic, then you are only dealing with AND and OR logical circuits and combinations of these.

For example 3 normally open switches in series to a lamp form an AND circuit. All three must be closed to energize the lamp.

Put these three switches in parallel and you have an inclusive OR circuit. Any one or more closed will energize the lamp.

A nromally closed contact is a NOT of its asserted condition.

.
 
080621-0847 EST

english bob:

I will add EXCLUSIVE OR to my previous comments.

An EXCLUSIVE OR logic function is strictly a two input one output device, and there is no word in the English language for this other than XOR.

In logic circuits one talks about TRUE or FALSE, 1 or 0, asserted or not asserted, HIGH or LOW to define binary states.

Combinatorial logic functions are define by truth tables such as:

Code: 
Truth tables

 X and Y are binary inputs, Output is a binary output


AND Function

 X   Y    Output

 0   0       0
 0   1       0
 1   0       0
 1   1       1


NAND Function (the output of AND is negated)

 X   Y    Output

 0   0       1
 0   1       1
 1   0       1
 1   1       0


OR Function

 X   Y    Output

 0   0       0
 0   1       1
 1   0       1
 1   1       1


NOR Function (the output of OR is negated)

 X   Y    Output

 0   0       1
 0   1       0
 1   0       0
 1   1       0


XOR Function

 X   Y    Output

 0   0       0
 0   1       1
 1   0       1
 1   1       0


NOT XOR Function

 X   Y    Output

 0   0       1
 0   1       0
 1   0       0
 1   1       1


NOT Function

 X        Output

 0           1
 1           0


Note:
If you complement (negate) the inputs to a NAND circuit you convert 
the NAND into an OR. Complement the inputs to a NOR and you convert 
it to an AND.

Tie all inputs together of either a NAND or NOR and you create a NOT 
element.

Find a book on Boolean arithmetic or Symbolic logic and you can study this further.

.
 
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