Front End Turns PC Sound Card into High-Speed Sampling Oscilloscope

Various software packages enable PC sound cards to provide oscilloscope-like displays, but the low-sample-rate, high-resolution ADCs and ac-coupled front ends have limited bandwidths. For repetitive waveforms, a sampling front-end stretches the time axis, allowing the PC to be used as a high-speed sampling scope. This article describes a front end and probe that provide an appropriate adaptation.