# NOT logic function

Discussion in 'General Electronics Chat' started by paul33, Mar 5, 2008.

1. ### paul33 Thread Starter New Member

Mar 5, 2008
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Is a NOT logic function principally series or parallel?

2. ### SgtWookie Expert

Jul 17, 2007
22,201
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This sounds like a homework question.

To answer your question with a question, what are you going to NOT?

3. ### Audioguru Expert

Dec 20, 2007
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A logic inverter is not a gate. It is not a NOT gate. It is a logic inverter!

Who made up that stupid name???

4. ### thingmaker3 Retired Moderator

May 16, 2005
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Too late, my good fellow. [SIZE=-1]Britannica, Wikipedia, and even All About Circuits list the inverter as a "NOT gate." Language evolves whether we want it to or not. I don't like it either, but we're vastly outnumbered.

Since it inverts its single input, I'd say the output "refers to a previous value of itself."
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5. ### Dave Retired Moderator

Nov 17, 2003
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NOT is probably the favoured terminology in order to avoid confusion with the DC-AC inverter circuit. I tend to find inverter is more of a US-centric word; I have rarely come across the inverter logic gate in formal discussions/teachings here in the UK. We still use the word of course!

Dave

6. ### nomurphy AAC Fanatic!

Aug 8, 2005
567
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Is a NOT gate not a gate? When is a gate not a NOT gate? Is a non-inverter not a gate, or is it a NOT NOT gate?

Are you saying you can't have a gate, and NOT it too?

....
To OP -- to invert a signal, would you do it in series or in parallel?

7. ### mik3ca Active Member

Feb 11, 2007
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I would agree that an inverter is a "NOT" gate.
invert means to make something the opposite,
"NOT" means the opposite.
and since opposite = opposite, Inverter = NOT!

as for connecting them, why worry about series or parallel?
the only time parallel would make sense is if you made a flip-flop with two special gates (and "NOT" gates do qualify here)

8. ### Audioguru Expert

Dec 20, 2007
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You can connect Cmos "logic inverters" (CD4069 or 74C04) in parallel to increase their output current.

I have never seen a datasheet for "logic inverters" that call them Not Gates. They are called logic inverters. Teachers call them Not Gates but I don't know why.

9. ### beenthere Retired Moderator

Apr 20, 2004
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It's because they're inverters, not gates.

10. ### nomurphy AAC Fanatic!

Aug 8, 2005
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Sorry to burst your bubble, but take a look at the highlighted protions of the attached datasheet:

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11. ### beenthere Retired Moderator

Apr 20, 2004
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Not my bubble - I've been working with logic (and making bad puns) for over 40 years.

A definition of a gated signal is one that is controlled by another. That requires at least two inputs, so that could also define the minimum number of inputs to perform logic gating. An inverter doesn't meet that criterion. This is at the level of "you say tomato.." and makes no difference.

12. ### nomurphy AAC Fanatic!

Aug 8, 2005
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Apparantly the industry doesn't agree with your definition or criteria (at least not T.I., and see attached for ON-semi). However, your above definition can fall into the category of "complex" gate.

(loj´ik gāt) (n.) A type of circuit (or collection of transistors and resistors) that regulates the flow of electricity (or optical signals in fiber optic computing systems) that determines the Boolean logic computers use to make complex logical decisions. The three simple gates—AND, OR and NOT—combine to perform complex decision making processes. The on or off state of a logic gate corresponds to the binary values.

The complex logic gates are XOR (exclusive-OR), NAND (NOT-AND), NOR (NOT-OR), and XNOR (exclusive-NOR).

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13. ### studiot AAC Fanatic!

Nov 9, 2007
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Actually, no.

A gated signal may pass or not pass a single diode gate depending upon level.
There is no other signal involved.

14. ### studiot AAC Fanatic!

Nov 9, 2007
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The original question did not refer to gates.
In fact the simplest implementation of boolean algebra is with switches and the question makes sense in this context.

A times A' is a series connection equal to zero. AA'=0
A plus A' is a parallel combination and equal to unity. A+A'=1