HOW TO SENSE 12 VOLT DC VOLTAGE USING MICROCONTROLLER?

[Raj]

Yup,its a cultural thing.
People don't play attention to the important parts otherwise.


It's origin? our schooling system I guess.
The textbooks are huge but the parts students are supposed to learn are one or two lines per page,made to underline by our teachers. I still used to read the whole book

[Raj]

Raj n Kumar, why Indians love to use eyes blinding text all the time ? Not only you two, but I have seen too many at various forums as well.

Is it a cultural thing ? As common netiquette, its like shouting out loud when talking, everytime. 

Perhaps their love of eye burning text is linked to their taste for mouth burning spicy food?

Anyway, I recently posted this schematic in another thread. It converts a voltage ranging from 10V to 15V to 0V to 5V, which can be read from an MCU ADC pin.

https://www.eevblog.com/forum/projects/mesuring-a-12v-lead-acid-battery/msg1644677/#msg1644677

Interesting...I would have taken a way expensive route with negative voltage or ground isolation from input,making input ground, -10+diode drop equalvant and a diode at input,

or simply use 16 bit mode adc ( there's an article on microchip's website on how to do that on 10 but atmegas without external adc)

[Raj]

Hey orignal post author,
If I am guessing correctly,I think you are trying to make a car voltmeter or a battery monitor of some sort,right?

[wabhavkumar]

Hello all,
can anyone suggest, below attached circuit diagram can work or not?
if not, please suugest pc817 optocoupler circuit for sensing 12 volt using microcontoller.

[Raj]

This will work

[wabhavkumar]

this circuit is not working at 50 meters circuit

[Mr. Scram]

thank you for the valuable reply. Please suggest optocoupler circuit.

What's wrong with a voltage divider? It seems by far the simplest solution. Without more information we're left guessing.

[Zero999]

this circuit is not working at 50 meters circuit

What do you mean by 50 meters circuit? It makes no sense.

Is this connected to circuit, via a long piece of cable? If so, then you should have said before!

[Kjelt]

At 50 metres you should put a microcontroller on both ends and connect with rs422/485 or ethernet

[Mr. Scram]

What do you mean by 50 meters circuit? It makes no sense.

Is this connected to circuit, via a long piece of cable? If so, then you should have said before!

This community seems so eager to help that it often starts offering advice before someone has bothered to properly specify the problem. That doesn't foster proper behaviour.

[SparkyFX]

I don´t see why that reed switch should not operate at the microcontrollers operating voltage. Or switch ground with a pull up?

[wabhavkumar]

I am really sorry for posting an incomplete question.
yes, if no/nc switch is connected with 50m length of wire, then this circuit is not working properly.
Can anyone suggest some better circuit?

[Raj]

go see Reply #20 on: 06-07-2018, 18:21:35

Use it.