Which circuits modify the return signal from the receiving transducer?

The receiver-amplifier circuits are designed to modify the return signal from the receiving transducer in ultrasonic testing. Once the transducer receives the ultrasonic waves that have traveled through the material and reflected back, the signal is typically very weak. The receiver-amplifier amplifies this weak signal to a usable level for further analysis.

In addition to amplification, receiver-amplifiers often include filtering components to eliminate noise and enhance the clarity of the signal, making it easier to interpret data from the NDT inspection. This functionality is critical for accurate defect detection and assessment in materials, ensuring that operators can make reliable decisions based on the test results.

Other circuits mentioned in the options serve different functions. The pulser generates the electrical signal that excites the transducer to emit ultrasonic waves, clock circuits manage timing functions in the system, and high-voltage circuits typically deal with powering the transducer rather than directly modifying the return signal. Understanding the distinct roles of these components is vital for comprehending how ultrasonic testing equipment operates effectively.