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Ch 38 Mr v
| Question | Answer |
|---|---|
| Outline three advantages of using a transistor as a switch. | The advantages of a transistor being used a switch are needing very low driving currents and voltages in order to set off the switching, being able to switch quickly and have no moving parts. |
| How does a photoconductive cell sense different light levels? | When there is enough light at the lens opening it passes enough current through the base to tourn the light on. Also by the amount of scattering on free electrons in the photoconductive cell which contacts the semiconductor substrate that enhances the res |
| A photoconductive cell cannot operate a lamp directly. why? | The photoconductive cell can not operate a light directly because there is no current conducted between the emitter, the collector, and the lamp. |
| In a typical transistor | timer circuit, what component discharges to provide the timing action? |
| Compare the operating points of a transistor switching and amplifying circuits. | Transistor switching circuits can turn off the collector or and the emitter the amplifier can not. |
| When transistors are used like variable resistors, what advantages do they have over the rheostats that they replace? | Transistors that act like variable resistors are lighter, smaller, and can control current more efficiently than a rheostat. |
| What are ac amplifiers used for? | AC amplifiers are used to increase the strength or level of small ac signals. |
| There are three basic configurator or methods of connecting transistors in circuits as amplifiers. How are these circuits named? | The circuits are named according to which transistor element is common to both output and input circuit. |
| There are three basic configurator or methods of connecting transistors in circuits as amplifiers. Which circuit connections are most widely used with Bipolar junctions transistors? | The most widely used circuit is the common |
| Name three subcircuits of a transistor voltage amplifier. | The three subcircuits of a transistor voltage amplifier are one circuit for the amplified ac output signal, one circuit for the weak ac input signal, and one circuit for dx current flow from the dc voltage source aka bias circuit. |
| A BJT is to be biased in order to reproduce the complete ac input signal. With no input signal present, how are the dc current levels set? | With no input signal present, the dc current levels set to the point where the transistor is turned half on. The DC base and collector currents are operating at a steady value. |
| What is the advantages of the voltage | divider bias circuit over the fixed |
| Why are coupling capacitors used on the input and output circuits of a transistor amplifier? | The use of coupling blocks of capacitors blocks the DC path to the output load to the resistor as to not change the bias and blocks the DC path on the input so that its resistance will not affect the dc bias currents. |
| Explain how the value a and b each affect the voltage gain of a given BJT Amplifier. The beta (Ic/Ib) of the transistor | The beta (Ic/Ib) of the transistor the greater the beta, the voltage gain will go up |
| Explain how the value a and b each affect the voltage gain of a given BJT Amplifier. The resistance value of the collector load resistor. | The resistance value of the collector load resistor. The higher the resistance the bigger the change the voltage change will be, given that current changes. |
| Explain the two simple steps involved to establish a load line on a collector family of curves for a BJT Common | emitter amplifier. |
| What is usually the best | operating point along the load line? |
| Define what is meant by a linear amplifier. | The linear amplifier will have an output signal that is the same as the input signal, only larger. |
| List three ways in which an amplifier output can be clipped or distorted. | The three ways in which an amplifier output can be clipped or distorted are operating to close to saturation, the amplifier is overdriven or the input signal is too large to be applied to the amplifier and operating too close to the cutoff. |
| Compare voltage | amplifying and power |
| Define the term bandwidth as it applies to amplifiers | When a range of frequencies over which the gain of an amplifier is maximum and remains relatively constant is known as bandwidth. |
| Explain the function of the output transformers as used in a BJT power amplifier circuit. | The function of the output transformer as used in a BJT power amplifier circuit is to have the same circuit requirement as a voltage amplifier except for the collector load resistor and is used in place of the load resistor. |
| What does a volume control consist of? | Volume control consists of a variable resistor that is manually adjusted to provide the requested listening out form the speaker. |
| Explain how it operates to set the volume? | It operates by setting the amplitude or voltage level signal input to the voltage amplifier. Then the current flows through the volume control resistor develops a voltage across it. By adjusting the contact on the resistor you adjust the percentage of tot |
| How is tone control of an audio amplifier achieved? | The tone control of an audio amplifier varies the levels of the Amplified sound recording to the listener's taste vary the frequency the audio amplifier highers or lowers the range that can be emphasized. |
| Explain the function of a transistor | oscillator circuit. |
| State the purpose of each of the following subcircuits in a transistor oscillator circuit: wave | producing circuit |
| State the purpose of each of the following subcircuits in a transistor oscillator circuit: amplifier circuit | The amplifier circuit amplifies the weak signal from the wave producing circuit which goes through amplification then on to the output. |
| State the purpose of each of the following subcircuits in a transistor oscillator circuit: feedback circuit | A bit of the output from the amplifier is fed back to the original wave generator circuit to keep the circuit operating. |
| What causes the oscillating current between a charged capacitor and an inductor connected in parallel? | The causes the oscillating current between a charged capacitor and an inductor connected in parallel The magnetic field of the inductor and is stopped by the resistance of the circuit. |
| What are power inverters used for? | Power inverters are used to convert DC to AC some electric vehicles use it. |
| green | oxygen |
| yellow | air |
| blue | nitrous oxide |
| white | vacuum |
| gray | carbon dioxide |
| purple | Waste air gas disposal |
| Black | Nitrogen |
| Brown | Helium |
| <1 mA | Imperceptible to touch |
| 10 mA | Skeletal muscle shock (can't let go) |
| 100 mA | Heart Stops aka Ventricular Fibrillation or "Vfib" |
| Macro shock | large amount of current flow, that can cause harm or death. Passes through the heart from two points on the body. 100 to 300 mA applied over the whole body |
| Microshock | small amounts of current flowing through a catheter or a lead directly to a sensitive area (usually the heart). 10µA to 100µA Most Dangerous because it can't be felt. It can be fatal. |
| The advantages of a transistor being used a switch are needing very low driving currents and voltages in order to set off the switching, being able to switch quickly and have no moving parts. | |
| How does a photoconductive cell sense different light levels? | When there is enough light at the lens opening it passes enough current through the base to tourn the light on. And also by the amount of scattering on free electrons in the photoconductive cell which contacts the semiconductor substrate that enhances the |
| A photoconductive cell cannot operate a lamp directly. why? | The photoconductive cell can not operate a light directly because there is no current conducted between the emitter, the collector, and the lamp. |
| In a typical transistor-timer circuit, what component discharges to provide the timing action? | In a typical transistor-timer circuit, the capacitor discharges to provide the timing action. |
| Compare the operating points of a transistor switching and amplifying circuits. | Transistor switching circuits can turn off the collector or and the emitter the amplifier can not. |
| When transistors are used like variable resistors, what advantages do they have over the rheostats that they replace? | Transistors that act like variable resistors are lighter, smaller, and can control current more efficiently than a rheostat. |
| What are ac amplifiers used for? | AC amplifiers are used to increase the strength or level of small ac signals. |
| There are three basic configurator or methods of connecting transistors in circuits as amplifiers. How are these circuits named? | The circuits are named according to which transistor element is common to both output and input circuit. |
| There are three basic configurator or methods of connecting transistors in circuits as amplifiers. Which circuit connections are most widely used with Bipolar junctions transistors? | The most widely used circuit is the common-emitter with Bipolar junctions transistors |
| Name three subcircuits of a transistor voltage amplifier. | The three subcircuits of a transistor voltage amplifier are one circuit for the amplified ac output signal, one circuit for the weak ac input signal, and one circuit for dx current flow from the dc voltage source aka bias circuit. |
| A BJT is to be biased in order to reproduce the complete ac input signal. With no input signal present, how are the dc current levels set? | With no input signal present, the dc current levels set to the point where the transistor is turned half on. The DC base and collector currents are operating at a steady value. |
| What is the advantages of the voltage-divider bias circuit over the fixed-base biased circuit? | The advantage of the voltage-divider bias circuit over the fixed-base biased circuit is that the voltage divider bias circuit increased the temperature stability of the amplifier which leads to a voltage gain. |
| Why are coupling capacitors used on the input and output circuits of a transistor amplifier? | The use of coupling blocks of capacitors blocks the DC path to the output load to the resistor as to not change the bias and blocks the DC path on the input so that its resistance will not affect the dc bias currents. |
| Explain how the value a and b each affect the voltage gain of a given BJT Amplifier. The beta (Ic/Ib) of the transistor | The beta (Ic/Ib) of the transistor the greater the beta, the voltage gain will go up |
| Explain how the value a and b each affect the voltage gain of a given BJT Amplifier. The resistance value of the collector load resistor. | The resistance value of the collector load resistor. The higher the resistance the bigger the change the voltage change will be, given that current changes. |
| Explain the two simple steps involved to establish a load line on a collector family of curves for a BJT Common-emitter amplifier. | The simple steps involved to establish a load line on a collector family of curves for a BJT Common-emitter amplifier is the transistor is considered to be an open circuit. Collector current zero and collector voltage will be Vcc. The transistor will be a |
| What is usually the best-operating point along the load line? | The best operating point is the center of the lead line. |
| Define what is meant by a linear amplifier. | The linear amplifier will have an output signal that is the same as the input signal, only larger. |
| List three ways in which an amplifier output can be clipped or distorted. | The three ways in which an amplifier output can be clipped or distorted are operating to close to saturation, the amplifier is overdriven or the input signal is too large to be applied to the amplifier and operating too close to the cutoff. |
| Compare voltage-amplifying and power-amplifying transistors | The voltage amplifier transistor will amplify the voltage higher or to a different level. The power amplifier transistor will amplify the power higher or level. Note you have to use a power amplifier transistor to get high voltage. |
| Define the term bandwidth as it applies to amplifiers | When a range of frequencies over which the gain of an amplifier is maximum and remains relatively constant is known as bandwidth. |
| Explain the function of the output transformers as used in a BJT power amplifier circuit. | The function of the output transformer as used in a BJT power amplifier circuit is to have the same circuit requirement as a voltage amplifier except for the collector load resistor and is used in place of the load resistor. |
| What does a volume control consist of? | Volume control consists of a variable resistor that is manually adjusted to provide the requested listening out form the speaker. |
| Explain how it operates to set the volume? | It operates by setting the amplitude or voltage level signal input to the voltage amplifier. Then the current flows through the volume control resistor develops a voltage across it. By adjusting the contact on the resistor you adjust the percentage of tot |
| How is tone control of an audio amplifier achieved? | The tone control of an audio amplifier varies the levels of the Amplified sound recording to the listener's taste vary the frequency the audio amplifier highers or lowers the range that can be emphasized. |
| Explain the function of a transistor-oscillator circuit. | The function of a transistor-oscillator circuit is to generate a continuous undampened output. |
| State the purpose of each of the following subcircuits in a transistor oscillator circuit: wave-producing circuit | The wave producing circuit generates the wave and determines the frequency of the oscillator. |
| State the purpose of each of the following subcircuits in a transistor oscillator circuit: amplifier circuit | The amplifier circuit amplifies the weak signal from the wave producing circuit which goes through amplification then on to the output. |
| State the purpose of each of the following subcircuits in a transistor oscillator circuit: feedback circuit | A bit of the output from the amplifier is fed back to the original wave generator circuit to keep the circuit operating. |
| What causes the oscillating current between a charged capacitor and an inductor connected in parallel? | The causes the oscillating current between a charged capacitor and an inductor connected in parallel The magnetic field of the inductor and is stopped by the resistance of the circuit. |
| What are power inverters used for? | Power inverters are used to convert DC to AC some electric vehicles use it. |
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