What's the opposite of a NOT gate?

  • Thread starter Thread starter golmschenk
  • Start date Start date
  • Tags Tags
    Gate
Click For Summary

Discussion Overview

The discussion revolves around identifying a circuit component that serves as the opposite of a NOT gate, specifically focusing on the need for a device that can provide current based on an input signal without requiring the sending circuitry to operate at higher current levels. The conversation touches on various circuit designs and components, including buffers and logic gates.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks a circuit component that can output current based on an input signal, suggesting that the current levels should not be high from the sending circuitry.
  • Another participant identifies the component as a buffer, providing a link to a resource for further information.
  • There is a suggestion that a relay might also serve the purpose, though this is not elaborated upon.
  • Multiple participants mention that a buffer can be constructed using two NOT gates or an AND gate configured with identical inputs.
  • One participant proposes using an operational amplifier (op-amp) as a voltage follower as an alternative solution.
  • Another contribution notes that a buffer is internally made of two inverters and discusses the implications of using an even number of buffers for driving long distances.
  • There is a linguistic concern raised about the classification of buffers within the hierarchy of logic functions, with one participant questioning the terminology used.
  • Another participant emphasizes that buffers do not perform logical operations but are instead used to drive higher loads.

Areas of Agreement / Disagreement

Participants generally agree that a buffer is the appropriate component for the described need, but there are differing views on the classification and terminology surrounding buffers in relation to logic functions.

Contextual Notes

Some participants express uncertainty regarding the linguistic progression of logic gates and the role of buffers, indicating that the definitions and classifications may not be universally accepted.

golmschenk
Messages
35
Reaction score
0
I essentially need the opposite of a NOT gate. I know that sounds silly, but what I'm really looking for is something that will provide the current based on the signal sent to it so that the more sensitive circuitry sending the signal doesn't have to run higher current levels. I've found I could do this using two NOT gates in a row or an AND gate and just using both the inputs on the AND gate to be the same, but I'm guessing there must be a circuit piece already built for this. One that I can provide a signal and supply voltage to and it will provide the output current. For what I'm doing the signal voltage and supply voltage need not be the same. I just need to make sure the circuitry sending the signal doesn't have to send the higher current with the signal itself. Thanks!
 
Engineering news on Phys.org
What you are describing is called a http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/buffer.html" .
 
Last edited by a moderator:
Are you looking for a relay?

Edit: Jambaugh looks more capable at this, I'd look at his suggestion first :)[/size]
 
OK, so you want a buffer.

Using two NOT gates, or an AND gate, or some other form of buffer made from whatever logic gate chips you have available should be fine.

Alternatively, maybe use an opamp voltage follower? Or investigate buying dedicated buffer chips.
 
A buffer is made of 2 inverters internally. If you need to drive a long distance and need 2 (or any even number) buffers, using a series of even number of inverters is a better solution.

If you don't care about the difference in rise time and fall time, you can use pretty much any combinational logic gate to make it a buffer.
 
Last edited:
Awesome. Thanks for the help!
 
So the natural progression is "AND, OR, NAND, NOR, NOT, BUFFER"? Sorry, but that just doesn't sound right to me (linguistically). Let me do some research.
 
Also called a follower.
 
mhearne said:
So the natural progression is "AND, OR, NAND, NOR, NOT, BUFFER"? Sorry, but that just doesn't sound right to me (linguistically). Let me do some research.
What "progression"?

Buffers aren't really considered a logic function, since they don't really do anything to the signal, logically speaking. They just help it drive higher loads.
 

Similar threads

Replies
12
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
4K
Replies
2
Views
2K
  • · Replies 42 ·
2
Replies
42
Views
6K
Replies
6
Views
5K
Replies
55
Views
8K
  • · Replies 25 ·
Replies
25
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
13
Views
3K