In short, [Christer] needed a high-frequency active differential oscilloscope probe, and they’re not cheap. So he built one himself. With some minor tweaking on the input damping resistors ...

If you have a single-ended signal and you want to view it on your scope, your choice is either a passive or active probe. Usually some kind of passive probe will be most available. These commonly ...

Identity of the active species. A quality chemical probe has sufficient chemical and physical property data to permit utilization in in vitro and cell-based assays with interpretations of results ...