Comparators: What Hardware to Use in 12v Circuit?

Thread Starter

oKCfGYhmJQi

Joined May 3, 2019
60
I have another thread where some forum members have helped me formulate my thinking on a project, and as we've made our way through the "big picture" questions I've come to realize that I might be better served by asking some of the smaller questions in their own threads, so I'm creating a few. For reference, here is the "root" thread: https://forum.allaboutcircuits.com/threads/high-speed-actuation-sensing.159382/
https://forum.allaboutcircuits.com/threads/high-speed-actuation-sensing.159382/
Groundwork: I've read a little bit about comparators etc., but I'm unclear as to how logic would be implemented in the circuit described in the above-linked post.

Questions:
  • Are comparators discrete chips?
  • How would I go about specifying particular components?
 
Last edited:

wayneh

Joined Sep 9, 2010
16,102
Questions:
  • Are comparators discrete chips?
That's like a jumbo shrimp, a component is either discrete or part of an integrated IC, or chip. But I think the answer to your question is yes, a comparator is a single IC you buy for that purpose. In fact the typical LM393 has 4 comparators on the chip.
  • How would I go about specifying particular components?
Start with the LM393 and if it doesn't fit for some reason, then you have identified a specification that requires something beyond the generic specs.
 

Thread Starter

oKCfGYhmJQi

Joined May 3, 2019
60
That's like a jumbo shrimp, a component is either discrete or part of an integrated IC, or chip. But I think the answer to your question is yes, a comparator is a single IC you buy for that purpose. In fact the typical LM393 has 4 comparators on the chip.

Start with the LM393 and if it doesn't fit for some reason, then you have identified a specification that requires something beyond the generic specs.
Awesome, thank you. So now a question on how to use the coparator as an AND gate. Would it be a simple matter of adding resistors as shown at the following link?

https://www.instructables.com/id/Use-Comparator-as-Logic-AND-Gate/
 

Papabravo

Joined Feb 24, 2006
12,405
That's like a jumbo shrimp, a component is either discrete or part of an integrated IC, or chip. But I think the answer to your question is yes, a comparator is a single IC you buy for that purpose. In fact the typical LM393 has 4 comparators on the chip.

Start with the LM393 and if it doesn't fit for some reason, then you have identified a specification that requires something beyond the generic specs.
LM393 is a dual. The quad part is LM339.
 

Papabravo

Joined Feb 24, 2006
12,405
Awesome, thank you. So now a question on how to use the coparator as an AND gate. Would it be a simple matter of adding resistors as shown at the following link?

https://www.instructables.com/id/Use-Comparator-as-Logic-AND-Gate/
A comparator is not an all digital device, like an AND gate. A comparator has two analog inputs, and a single digital open collector output. The output tells you that one analog input is above or below the other one, but not by how much.
 

wayneh

Joined Sep 9, 2010
16,102
Damn dyslexia, yes. My mom was German and born left handed. In those days they beat left handed children to force them to write with their right hand. Germans put the verb and subject (or noun?) in opposite order from English. So she struggled with direction and order. I may have got a touch of it.
 
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