Comparator Project.

Thread Starter

MAA01

Joined Sep 21, 2021
12
I am working on a sensor integrated with a signal conditioning circuit.I want to use output as a decision. Output of signal conditioner is around 2.5Vdc to 3.5Vdc.now I want to make a decision if the output is greater than this reference, i need to actuate a simple indication.if out put is less than this set reference, then there shiuld be no indication energized.
Thanks
 
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MrChips

Joined Oct 2, 2009
24,398
Welcome to AAC!

Here is an example of an analog comparator circuit based on LM339 quad comparator IC.
Just about any analog comparator chip can be substituted. As a general rule, analog comparator ICs have open-collector outputs. In other words, you must provide an external load connected between the output pin and the positive supply line.

Substitute the supply voltage, R1 and R2 to suit your desired reference voltage.

1632272097437.png
 

crutschow

Joined Mar 14, 2008
27,893
MrChips' circuit should do what you want.
You could also use an LM393 which is a dual comparator version of the quad LM339.

The circuit lights the LED when the (-) input is at higher voltage than the (+) input (comparator output is low).
 

Thread Starter

MAA01

Joined Sep 21, 2021
12
Th
Welcome to AAC!

Here is an example of an analog comparator circuit based on LM339 quad comparator IC.
Just about any analog comparator chip can be substituted. As a general rule, analog comparator ICs have open-collector outputs. In other words, you must provide an external load connected between the output pin and the positive supply line.

Substitute the supply voltage, R1 and R2 to suit your desired reference voltage.

View attachment 248547
Thankyou.
Will try it
 

LowQCab

Joined Nov 6, 2012
1,183
A Mass-Flow-Sensor is not a good choice for determining Air-Velocity.

Do You want to measure Mass-Air-Flow by Weight, or Air-Velocity ( Air-Speed) ?
.
.
.
 

Thread Starter

MAA01

Joined Sep 21, 2021
12
Welcome to AAC!

Here is an example of an analog comparator circuit based on LM339 quad comparator IC.
Just about any analog comparator chip can be substituted. As a general rule, analog comparator ICs have open-collector outputs. In other words, you must provide an external load connected between the output pin and the positive supply line.

Substitute the supply voltage, R1 and R2 to suit your desired reference voltage.

View attachment 248547
This works in simulation fine but on hardware no led glows at any voltage varied. There is 0.4V wth respect to ground at output 1 of cmparatr if i dont connect any thing at ths pin.And I get 3.3V when i connect led as sugestd by your circuit.there is no variation of voltage at ths point even i vary at input to chnge reference
 

MrChips

Joined Oct 2, 2009
24,398
Show us your circuit diagram, not the one from the link.
Also a photograph of your actual layout would be helpful. This way we might be able to spot your errors.
 

Audioguru again

Joined Oct 21, 2019
3,632
Google and I never heard about your "S339" then it is not an LM339.
We also never heard about the "AUC" company who makes it.
Can you post the datasheet of your S339?
 

DickCappels

Joined Aug 21, 2008
7,836
Some of the best chips are made in Asia. It is not where its made, it's how production and quality are managed that makes the difference.
 
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