# current measurement to send to a comparator

#### Hugo100

Joined May 6, 2022
4
Good day everyone,
I´m building a very basic circuit, 4.5V., 1 fixed resistance, 1 variable resistance. I want to measure the current based on the changes the variable resistance have. What would you recommend? thank you in advance for taking the time to help.

#### Ian0

Joined Aug 7, 2020
8,947
Measure the voltage across the fixed resistance. Divide by the value of the fixed resistance.
(That assumes that the two resistances are in series, but you didn’t say how they are connected)

#### Hugo100

Joined May 6, 2022
4
Measure the voltage across the fixed resistance. Divide by the value of the fixed resistance.
(That assumes that the two resistances are in series, but you didn’t say how they are connected)
That is actually a good point. they will be connected in series to have a voltage variation. Is there a microprocessor that you know that can measure that change in voltage and send a signal to a comparator to activate another circuit?

#### LowQCab

Joined Nov 6, 2012
3,584
If You will describe what You are trying to accomplish, in detail,
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#### Ian0

Joined Aug 7, 2020
8,947
That is actually a good point. they will be connected in series to have a voltage variation. Is there a microprocessor that you know that can measure that change in voltage and send a signal to a comparator to activate another circuit?
Most of them.
But why do you need a microprocessor to send the signal to the comparator, when you can just connect the signal to the comparator?

#### Hugo100

Joined May 6, 2022
4
Most of them.
But why do you need a microprocessor to send the signal to the comparator, when you can just connect the signal to the comparator?
Hi Ian0! Thank you for your suggestion. I looked at different options and I think this can work. What I want to do is to measure a voltage and send it to a comparator and if the value is above what I will specify, I want to turn on an LED. if it is below, I want to turn on a different LED. Which comparator do you recommend? Can this comparator send a signal to turn on the LED or can you suggest something? Thank you so much for your kind attention

#### WBahn

Joined Mar 31, 2012
29,510
So will one of two LEDs always be on? That makes things a lot simpler since you can wire one LED to turn on with a LO signal and the other to turn on with a HI signal.