Can i use a op-amp(741) like this ?

Hi everyone

Could i use a op-amp(741) as a comparator to convert sine-wave to square-wave like this?

Yes, but if -V is a negative voltage you can not wire it to an Arduino digital input pin.

Lefty

Yes, but if -V is a negative voltage you can not wire it to an Arduino digital input pin.

OH, I have a question
I got a wheel speed sensor, it generates AC
if it is connected like the above photo, what the +V and -V is connected respectively ?
+V to the Arduin power supply ? and -V ?
I am not quite sure about the op-amp comparator function...
Thanks a lot

f it is connected like the above photo, what the +V and -V is connected respectively

You connect the sensor to the ground and the op amp input. As it's AC it doesn't matter what way round it is.

ground to arduino ground.

  • of op amp to arduino +5V
  • of op amp to a -5V supply.

Thanks mike

but, how to define the resistor value ?

Thanks

but, how to define the resistor value ?

It is just a voltage divider and the op amp has a high impedance so virtually any value from 1K to 1M will do.

Don't forget retroleftie's comments.

It is just a voltage divider and the op amp has a high impedance so virtually any value from 1K to 1M will do.

Don't forget retroleftie's comments.

the -V must be supplied in negative voltage ?
or he meant the output voltage could not be negative ?

He meant that the circuit as drawn will put negative voltages into the input of the arduino which will destroy it. Therefore you must put a series diode in line with the output, and something like a 1K pull down resistor on the arduino input you use.

oh
thanks
now i get it
but how could a get a -5V into the op-amp ?

but how could a get a -5V into the op-amp

Using the battery mentioned in a previous post. +ve of the battery to ground, -ve of the battery to the op amp.