38 4-25.   Which of the following formulas is used to figure the output amplitude of a parallel-diode limiter? 1. 2. 3. 4. 4-26.   THIS QUESTION HAS BEEN DELETED. 4-27.   THIS QUESTION HAS BEEN DELETED. 4-28.   In a parallel-negative limiter, how is the diode biased (a) by the positive half of the input sine wave and (b) by the negative half? 1.   (a) Forward (b) forward 2.   (a) Forward (b) reverse 3.   (a) Reverse (b) reverse 4.   (a) Reverse (b) forward 4-29.   If a sine wave is applied to a parallel- negative limiter with positive bias, what is the polarity of the output voltage? 1.   Positive at all times 2.   Negative at all times 3.   Positive during the positive portion of the input cycle and negative during the negative portion 4.   Negative during the positive portion of the input cycle and positive during the negative portion Figure 4B.—Parallel-limiter input and output waveforms. IN ANSWERING QUESTION 4-30, REFER TO FIGURE 4B. 4-30.   If the diode in the parallel limiter were reversed, what portions of the input waveform would be limited? 1.   Positive peaks only 2.   Negative peaks only 3.   All hut the positive peaks would be limited 4.   All but the negative peaks would be limited 4-31.   Which of the following circuits would be used to fix the upper or lower extremity of a waveform at a specific value? 1.   Clamper 2.   Limiter 3.   Counter 4.   Amplifier