🔍 Key Concepts

• Difference between analog and digital signals in speed sensing • How each type of tachometer converts shaft rotation into an electrical output • Which devices use pulses or on/off changes versus smooth, proportional voltage

💭 Think About

• For each option, ask: does this device output a smooth, continuously varying voltage or a series of distinct pulses? • Think about which sensors typically use light/dark interruptions or switching elements tied to the shaft speed. • Consider how a brush-type device normally generates its output compared with solid-state or optical devices.

✅ Before You Answer

• Identify which choice is most clearly associated with a pulsed (on/off) output rather than a smooth analog voltage. • Confirm which tachometers are commonly described as generating a frequency or pulse train proportional to speed. • Eliminate any option that normally produces a continuous analog voltage proportional to speed, not discrete digital levels.