SDRs have been a game changer for radio hobbyists, but for ham radio applications, they often need a little help. That’s especially true of SDR dongles, which don’t have a lot of selectivity in the HF ...

Many sensors have a small analog signal that rides on top of a larger dc pedestal. For these circuits (Fig. 1), the signal must be ac coupled and amplified before it’s digitized. The feedback of an ...

This is active high pass filter circuit for 327Hz frequency using LM741. It will use to build Harmonic at 3 of 130.81 frequency have the value at least. More than the frequency Fundamental 30 dB, for ...

Several manufacturers offer op amp-based filter design tools [1-3]. Some tools choose off-the-shelf capacitor values, but others select non-standard ones. The option to alter passive component ...