Oscilloscope

Key controls:

• Vertical — volts/division, coupling (DC/AC), offset.
• Horizontal — time/division.
• Trigger — level, edge and mode (auto/normal/single) to freeze a repeating or one-off event.

Bandwidth: pick a scope with at least 3–5× the signal's frequency; rise-time relation $t_r \approx 0.35 / BW$.

Probes: use ×10 probes for most work (less loading, more bandwidth), compensate them with the calibration square wave, and keep the ground lead short.

Danger: the probe ground is connected to mains earth on most bench scopes. Clipping it onto a non-isolated mains circuit creates a short circuit. Use a differential probe instead.