Multimeters

The one tool that tells you what's actually happening in a circuit.

A multimeter measures voltage, current, and resistance (and often more) with a single handheld device and two probes.

• Voltage (V): touch the probes across two points — meter set to DC or AC volts to match your circuit.
• Resistance (Ω): touch the probes across a component with power removed from the circuit.
• Current (A): the meter must go in series, becoming part of the circuit itself — the trickiest of the three to use correctly.