To verify a signal is present between two points in a circuit, which instrument would you use?

• A. Butt set
• B. Tone generator
• C. Clamp meter
• D. Signal tracer

Answer: (A)

Verifying a signal between two points requires direct access to the circuit and a way to hear or observe what’s on the line. A butt set provides exactly that: you connect its two leads across the points in question and can listen for the signal, dial tone, or line activity, and even check line voltage or continuity. This immediate feedback confirms there is a usable signal path between the two points.

A tone generator by itself just injects a tone into a conductor; without a receiver at the other end, you can’t be sure the tone is present where you need it. A signal tracer helps you follow a live signal along a circuit, but it’s more about locating where a signal exists rather than giving a straightforward yes/no test of signal presence between two fixed points. A clamp meter measures current and doesn’t indicate whether a signaling path exists between two points in a circuit.

So, the tool that directly confirms signal presence between two points is the butt set.