# Comparator problem?

Discussion in 'Homework Help' started by killer00, Oct 6, 2010.

1. ### killer00 Thread Starter New Member

May 6, 2010
11
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i need an explanation on how comparator work because couldn't find any
website that would explain it good. Don't know if I'm doing it right, any help on filling the truth table be great.

2. ### PRS Well-Known Member

Aug 24, 2008
989
35
Hello killer. Comparators don't involve truth tables in any way that I know of. What they do do is compare a voltage under test with a reference voltage. If the tested voltage is greater than the threshold voltage of the comparator, they output a specific voltage, usually 5 volts for TTL logic. You seem to be confusing a comparator with a decoder.

3. ### killer00 Thread Starter New Member

May 6, 2010
11
0
How do I do the Circuitry?

Nov 25, 2009
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5. ### killer00 Thread Starter New Member

May 6, 2010
11
0
The problem is I don't really understand how a Comparator works.

6. ### Georacer Moderator

Nov 25, 2009
5,151
1,266
In order to get good anwers you need to make good questions. Asking how a comparator works is too vague. You mean how it is wired and with which component is it made of in order to perform the operation it does? If so, I already answered you in my previous post.

If you are wondering what does a comparator exactly do, well, that's easier: It compares.
It takes as an input two multidigit numbers A and B (4-bits in this case) and tells us which one is bigger. It has 3 output pins that correspond to 3 states A<B, A>B and A=B. It activates each accordingly to the situation. You can also specify its operation with more details in cases of parity, but that's too specific to care to explain.