51801. How many semiconductor layers are thyristors constructed with?
51802. Your boss has asked you to recommend a thyristor that will enable you to turn it on with a pulse and also turn it off with a pulse. Which of the following should you recommend?
51803. An SCR acts to control the speed of an electric motor by ________ the ________ of the pulse delivered to the motor.
51804. Which symbol represents a UJT?
51805. The anode-to-gate voltage can be used to turn the PUT on or off.
51806. In an SCR-based half-wave phase-control circuit, a diode is connected in series with the anode.
51807. The SCS is turned on with the cathode gate, and turned off with the anode gate.
51808. UJTs can only be used to trigger triacs, not SCRs.
51809. The SCR is a device that can be triggered off by a pulse applied to the gate.
51810. Thyristors are 4-layer semiconductor devices.
51811. The diac can conduct current in either direction and is turned on when a breakover voltage is exceeded.
51812. The triac is similar to an SCR, but it provides conduction for both halves of the ac wave.
51813. The triac can be turned on or off by a pulse at the gate.
51814. The SUS is also known as a Shockley diode.
51815. The ________ can be externally programmed to turn on at a desired anode-to-gate voltage level.
51816. You need a very efficient thyristor to control the speed of an AC fan motor. A good device to use would be
51817. An application of a(n) ________ is in a lighting system for power interruptions.
51818. Which of the following is used as a filler in rubber tyres?
51819. The silicon-controlled switch (SCS) is similar in construction to the
51820. Which transistor bias circuit provides good Q-point stability with a single-polarity supply voltage?
51821. Refer to this figure. In the voltage-divider biased npn transistor circuit, if R2 opens, the transistor is
51822. Ideally, for linear operation, a transistor should be biased so that the Q-point is
51823. The most stable biasing technique used is the
51824. Refer to this figure. The value of IB is
51825. What is the Q-point for a fixed-bias transistor with IB = 75 A, DC = 100, VCC = 20 V, and RC = 1.5 k?
51826. Emitter bias requires
51827. Refer to this figure. The value of DC is
51828. Refer to this figure. Assume that IC IE. Find VE.
51829. Refer to this figure. In the voltage-divider biased npn transistor circuit, if RC opens, the transistor is
51830. Which transistor bias circuit arrangement has poor stability because its Q-point varies widely with DC?
51831. What is the most common bias circuit?
51832. Refer to the given figure. The most probable cause of trouble, if any, from these voltage measurements would be
51833. Refer to this figure. Determine IC.
51834. At saturation the value of VCE is nearly ________, and IC = ________.
51835. Voltage-divider bias has a relatively stable Q-point, as does
51836. Refer to this figure. Assume IC IE. Determine the value of RC that will allow VCE to equal 10 V.
51837. The linear (active) operating region of a transistor lies along the load line below ________ and above ________.
51838. The input resistance of the base of a voltage-divider biased transistor can be neglected
51839. Refer to this figure. The value of IC is
51840. Which transistor bias circuit arrangement provides good Q-point stability, but requires both positive and negative supply voltages?
51841. Refer to this figure. Calculate the current I2.
51842. Refer to this figure. In the voltage-divider biased npn transistor circuit, if R1 opens, the transistor is
51843. Changes in DC result in changes in
51844. Collector-feedback bias provides very poor stability with negative feedback from collector to base.
51845. A transistor is operating in a linear fashion at saturation.
51846. Base biasing is common in relay driver circuits.
51847. The formula DC = IB/IC is correct.
51848. The base bias circuit arrangement provides poor stability because its Q-point varies widely with DC.
51849. A pnp transistor requires the same bias polarities as the npn transistor.
51850. The purpose of biasing is to establish a proper Q-point.