Basic comparator chip

Thread Starter

MBG

Joined Jan 30, 2022
23
I have an LM358 that I'm using now for a very simple comparator. I just set it at 3v and have it go high (5v) when it exceeds the 3v. Aren't there some simple DIP 8 chips that can do the same thing and are designed to be comparators? Maybe with more precision and schmitt trigger output etc? (I can't remember). I'm a hobbyist so these things aren't always on the top of my head. -- thanks for any help.
 

sghioto

Joined Dec 31, 2017
3,315
Aren't there some simple DIP 8 chips that can do the same thing and are designed to be comparators?
The LM393 is a dual comparator chip. Depending on what the output is connected to may not be a better choice then a LM358.
Parts count will probably be the same.
 

dl324

Joined Mar 30, 2015
14,708
I have an LM358 that I'm using now for a very simple comparator. I just set it at 3v and have it go high (5v) when it exceeds the 3v.
Opamps are generally a poor substitute for a comparator. A schematic of how it's being used would be helpful.

To have an LM358 output go to 5V, you need to be using a power supply greater than 5V. That won't be the case with a traditional open collector comparator output.
Aren't there some simple DIP 8 chips that can do the same thing and are designed to be comparators?
Yes. LM393 is my go to.
Maybe with more precision and schmitt trigger output etc?
The inputs of most comparators will be the same an an opamp. You can pay more for devices with low offset voltage/current or you can compensate for them. Both will require additional circuitry to implement a Schmitt function.
 

Ian0

Joined Aug 7, 2020
5,562
I have an LM358 that I'm using now for a very simple comparator. I just set it at 3v and have it go high (5v) when it exceeds the 3v. Aren't there some simple DIP 8 chips that can do the same thing and are designed to be comparators? Maybe with more precision and schmitt trigger output etc? (I can't remember). I'm a hobbyist so these things aren't always on the top of my head. -- thanks for any help.
LM393
 

k1ng 1337

Joined Sep 11, 2020
584
Welcome to the site :)

What are you trying to achieve? Your description doesn't help much so taking some time to post your goal, your level of electrical knowledge and a best attempt at a schematic will go far in enabling the community to provide you with a practical solution.
 

Thread Starter

MBG

Joined Jan 30, 2022
23
Ok, thank you. I'll probably order some of those. What I'm trying to do is compare is to differentiate between a 3v signal that is set and a very small rise to 3.7v which I can't do very well with an LM358 set up as a comparator. But my 10k pot is pretty sloppy, maybe I can do it with a voltage divider and 1% resistors or something.
 

sghioto

Joined Dec 31, 2017
3,315
You can also limit the range of the pot by using two resistors to fine tune the targeted voltage.
1643825336254.png
 
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dl324

Joined Mar 30, 2015
14,708
What I'm trying to do is compare is to differentiate between a 3v signal that is set and a very small rise to 3.7v which I can't do very well with an LM358 set up as a comparator.
Post a schematic of your circuit.
 
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