51501. ________ is (are) the element(s) of a unijunction transistor's equivalent circuit.
51502. To turn on an SCS device, a ________ pulse must be applied to the anode gate terminal; to turn off the device, a ________ pulse is required.
51503. In a half-wave variable-resistance phase control operation, the control cannot be extended past a ________ phase displacement.
51504. ________ are areas of application for SCRs.
51505. Which of the following devices does not have a cathode terminal?
51506. Today, the SCR is more widely used than the TRIAC.
51507. Which of the following devices is unquestionably of the greatest interest today?
51508. Which of the following devices has a negative-resistance region in its characteristics curve?
51509. Determine RB1 for a silicon PUT if it is determined that h = 0.84, VP = 11.2 V, and RB2 = 5 k.
51510. A silicon power transistor is operated with a heat sink ( SA = 1.5ºC/W). The transistor, rated at 150 W (25ºC), has JC = 0.5º C/W, and the mounting insulation has CS = 0.6 ºC/W. What is the maximum power that can be dissipated if the ambient temperature is 50ºC and TJmax = 200 ºC?
51511. Refer to this figure. The dc voltage on the collector, VC, is
51512. What is the ratio of the secondary voltage to the primary voltage with the turn ratio in the windings?
51513. Class ________ amplifiers are normally operated in a push-pull configuration in order to produce an output that is a replica of the input.
51514. You find that there is an input signal on the base of Q1 and Q2. However, there is no output signal. You then measure the dc voltages on Q2 and find them to be all 0 V. The possible trouble might be
51515. Which type of power amplifier is biased for operation at less than 180º of the cycle?
51516. Class AB operation is ________ operation.
51517. The principal advantage(s) of MOSFETs over BJTs is (are)
51518. Which of the following instruments allows more precise measurement of the harmonic components of a distorted signal?
51519. In class B operation, at what fraction of VCC should the level of VL(p) be to achieve the maximum power dissipated by the output transistor?
51520. What is the maximum temperature rating for silicon power transistors?
51521. What is the maximum efficiency of a class A circuit with a direct or series-fed load connection?
51522. You have an oscilloscope across RL and it shows a zero signal voltage. The problem might be that
51523. Which class of amplifier operates in the linear region for only a small part of the input cycle?
51524. The Q-point is at cutoff for class ________ operation.
51525. Determine what maximum dissipation will be allowed for a 70-W silicon transistor (rated at 25ºC) if derating is required above 25ºC by a derating factor of 0.6 W/ºC at a case temperature of 100º.
51526. How many transistors must be used in a class B power amplifier to obtain the output for the full cycle of the signal?
51527. What transformer turns ratio is required to match an 8- speaker load so that the effective load resistance seen at the primary is 12.8 k?
51528. Which of the following is (are) power amplifiers?
51529. Refer to the figure. The maximum efficiency of this amplifier is
51530. Quiescent power is the power dissipation of a transistor
51531. Which of the power amplifiers is not intended primarily for large-signal or power amplification?
51532. Refer to this figure. This amplifier is operating as a ________ amplifier.
51533. By how much does the output signal vary for a class AB power amplifier?
51534. Which type of amplifier uses pulse (digital) signals in its operation?
51535. Which of the push-pull amplifiers is presently the most popular form of the class B power amplifier?
51536. Refer to this figure. The approximate voltages on the base, collector, and emitter, respectively, are
51537. Calculate the harmonic distortion component for an output signal having a fundamental amplitude of 3 V and a second harmonic amplitude of 0.25 V.
51538. Which amplifier is commonly used as a frequency multiplier?
51539. You find that there is no output signal. You measure the dc voltage of Q1 emitter and find it equal to 0 V. The trouble might be
51540. A class B amplifier operates in the linear region for
51541. Which of the following instruments displays the harmonics of a distorted signal?
51542. Calculate the efficiency of a transformer-coupled class A amplifier for a supply of 15 V and an output of V(p) = 10 V.
51543. ________ amplifiers primarily provide sufficient power to an output load to drive a speaker from a few watts to tens of watts.
51544. You have an application for a power amplifier to operate on FM radio frequencies. The most likely choice would be a ________ amplifier.
51545. Which of the following describe(s) a power amplifier?
51546. Categorize the power efficiency of each class of amplifier, from worst to best.
51547. Which operation class is generally used in radio or communications?
51548. In a class AB amplifier, if the VBE drops are not matched to the diode drops or if the diodes are not in thermal equilibrium with the transistors, this can result in
51549. The least efficient amplifier among all classes is
51550. In practice, the efficiency of a capacitively coupled class A amplifier is about ________%.