85VAC to 255 VAC Measurement from LM258

Brian Cavanagh

Other Parts Discussed in Thread: LM258

Hi All,

I found a circuit online that I modeled.

I'm reading in 85VAC - 255VAC to an LM258.

The output is going to a uC that ranges from 0 - 5V.

I"m only getting a 1V difference at the output over the entire range.

Can some look at the attached schematic and output graphs I created using TopSpice?

Thanks, Brian

0 JohnTucker over 8 years ago

Moving to the op amp forum...

0 Brian Cavanagh over 8 years ago in reply to JohnTucker

Thank you John, I apologize for not placing it in the correct location.

Have a great day.

Brian

0 JohnTucker over 8 years ago in reply to Brian Cavanagh

No problem...good luck with your project.

0 Ron Michallick over 8 years ago in reply to JohnTucker

Brian,

If I calculated correctly, Vo is 5V + VI/109 so you should have more output signal.

There is another way to scale you input signal.

Amplifiers forum