Question

In a magnetic tape recorder, the erase signal is a ________ signal.

• A. high strength and high frequency
• B. high strength and low frequency
• C. low strength and low frequency
• D. low strength DC

Hint:

The erase signal is typically generated by the same high-frequency oscillator circuit that provides the AC bias signal to the recording head. This ensures efficient, noise-free operation.

Answer 1

The Correct Option is A

Step 1: Understanding the Erase Process in Tape Recorders:
To record new audio over a previously used magnetic tape, the old magnetic patterns must be completely cleared. This is done by the erase head, which is positioned upstream of the recording head.

Step 2: Analyzing the Erase Signal Requirements:
The erase head requires a specific signal to clear the tape effectively:

• High Strength (Amplitude): The signal must generate a magnetic field strong enough to saturate the tape's magnetic particles, completely over-writing and randomizing any existing magnetic alignment.
• High Frequency: The signal must have a frequency well above the audible limit (typically $60\text{ kHz}\text{ to }100\text{ kHz}$). As the tape moves past the erase gap, the magnetic particles experience a rapidly alternating field that gradually decays to zero, leaving them in a completely randomized, demagnetized state with no audible residue.

Step 3: Conclusion:
Therefore, the erase signal must be a high-strength, high-frequency AC signal, corresponding to option (A).