Probing & Measurement Technique#

Connecting to a circuit without changing the thing being measured. Probe selection, ground leads, bandwidth, loading — the stuff that separates a real reading from an artifact.

• Am I loading the circuit? — Probe impedance vs. source impedance. When a 10 MΩ DMM or 10x scope probe is still too heavy. High-Z nodes, current sense resistors, and knowing when the measurement itself has changed the circuit.
• Is my probe bandwidth sufficient? — Matching probe bandwidth to signal bandwidth. A 20 MHz probe on a 50 MHz signal doesn’t just attenuate — it lies about edge shape.
• Is my ground connection adding artifacts? — Ground lead inductance, ringing from long ground clips, and why the spring-tip ground works best for anything fast.
• Which probe type for this situation? — Passive vs. active, 1x vs. 10x, current probes, differential probes, near-field probes. Choosing the right tool before the measurement begins.