I just started working in the Power Electronics domain and I am learning and understanding the concepts of electrical and electronic circuits.

Attached is the circuit diagram I am trying to understand and design.

At the Point_of_Interest, I want a circuit that extracts the AC signal (Sinusoidal 50V 60Hz in this case). Is it possible to design such a circuit? If so, can anyone please suggest me how to extract this signal?

Thanks. enter image description here

  • 4
    \$\begingroup\$ Coupling capacitor \$\endgroup\$
    – Matt Young
    Sep 1, 2015 at 20:37
  • \$\begingroup\$ What are you going to do with the AC? Is it just a signal to you that you want to analyze? Or do you want to allow the AC to get through so you can power something with it? If you just want the signal, you can use a capacitor in series with your detector. Try googling "DC blocking capacitor." \$\endgroup\$
    – user57037
    Sep 1, 2015 at 20:37
  • \$\begingroup\$ Alternative name for this application: "blocking capacitor". \$\endgroup\$
    – The Photon
    Sep 1, 2015 at 20:39
  • \$\begingroup\$ Thanks for the resposes. @ mkeith: I want to extract this AC signal and find its peak-to-peak, rms and frequency. \$\endgroup\$
    – S Kal
    Sep 1, 2015 at 21:04

1 Answer 1


you can use a coupling capacitor or a high pass filter The capacitor will block the DC but AC will pass.

enter image description here

enter image description here

  • \$\begingroup\$ I just want to add the comment for the OP that the R and C together form a low pass filter. The smaller the R is, the larger C will need to be in order to pass 50 Hz. If R becomes too small, C will become impractically large at 50 Hz. This is why I was asking what you want to do with the AC. \$\endgroup\$
    – user57037
    Sep 1, 2015 at 20:54
  • \$\begingroup\$ And, btw, this traditionally how the "AC" mode is implemented in oscilloscopes. \$\endgroup\$
    – TEMLIB
    Sep 1, 2015 at 21:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.