Lead Acid Battery voltage monitor

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ZeleC

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HEllo
i want to feed a logic signal to a Pic16F84 to notify me when the batteray is lower than a certain voltage , what kind of Opamp to use and if anyone one can give me the circuit
thank you.
 

PIC16F84 doesn't have AD converter.
Better choose PIC with ADC and connect battery to AD input pin through resistor voltage divider.
 
I made this comparator circuit and it worked fine when its left alone,and it flips between 0V and 3.66V but when connected to the PIC input a drop from from 3.66 to 1V what might be the problem ,???
I think it might help if to add a 74hc00 in between but im trying to avoid that due to the PCB space.
Thank you .
 

Hi Zelec

Most likely you would have configured that pin as an output. Check the TRIS register!

Also, why don't you consider a 311 comparator instead of the 358? Since it is open collector output you wouldn't have problems with the logic levels like 3.66V!


Giri
 

You r right vsgiri i have already checked it and it was an output ,plus i added a simple 2n2222 transistor at the output of my opamp to get a 0 - 5V flip at my PIC input
Thank you guys
 

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