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Mr V. final 1341
Mr V. final
| Term | Definition |
|---|---|
| State three ways in which transistors are used. | Transistors are used in three ways, to act as amplifiers to increases voltage or current, to be used as switches to turn off and on current, and to act like variable resistors to make the current flow very. |
| What are the two main families of transistors? | The two main families of transistors are field-effect transistors (FETs) and bipolar-junction transistors (BJTs). |
| In what two ways is the base region of a bipolar junction transistor different from that of the emitter and collector? | The emitter and the collector have thicker walls than the base region. Also, the base region has fewer doping atoms. |
| For what purpose is the base region used? | This base controls the current flow through the transistor. |
| Draw the schematic symbol and identify the leads of a PNP and an NPN bipolar junction transistor (BJT). | NPN PNP |
| What is the basic difference between the connection of a PNP and NPN bipolar junction transistor circuit? | The main difference between an NPN transistor circuit and a PNP transistor circuit is the opposite voltages and currents that are involved. |
| Name the two junctions found within a BJT. | There are two PN junctions. |
| State the type of biasing use for each junction in order to produce the required transistor action. | The emitter-base must be in forward biased with voltage and resistance values selected. While the collector-base junction must be in reverse bias and the biasing voltage must be higher than that of the emitter-base forward-biased voltage. |
| Compare the normal current flow through a forward biased and reverse-biased junction. | Forward bias will current flow, while reverse bias will have no current flow. |
| With reverence to a properly biased, complete bipolar junction transistor circuit; What determines the amount of collector for current flow? | The amount of collector current is determined by the amount of base current flow. |
| With no base current flow how much collector current flows? | There is none because there is an open. |
| In what does a small increase in base current flow result? | A small increase in base current flow will result in a larger collector current flow. |
| What is the operating current range of the base compared to that of the collector. | The base range current is smaller (micro- to milliamperes) than that of the collector current (mili to amperes). |
| State two ways in which power transistor packages differ from the small signal type. | The case and semiconductor material are larger. The way you install them is also different. |
| A digital multimeter set for the diode function test is used to check the emitter base junction of a bipolar junction transistor. what readings would expected if the junction is good? | The diode function test should read 700mV in a forward-bias direction and in reverse-bias direction should read over range. |
| An analog ohmmeter is used to check the collector to-emitter circuit of a BJT. What should be the normal resistance reading between these two points? | When testing a resistor you should use the collector-to-emitter test, the resistance should read infinite or very high. |
| explain the basic circuit configuration contained within a bipolar Darlington transistor. | The Darlington transistor pair is a way of setting up two bipolar transistors to let the smaller transistor act as base current for the larger transistor. |
| What is the main advantage of this configuration? | The main advantage of Darlingtons is that the manufacture can package them together so it becomes plug and play. |
| Compare the control of output current of a bipolar junction transistor (BJT) with that of a field-effect transistor (FET). - | Bipolar junction transistors are current driven and the input current controls the output current. Since a FET transistor doesn't require much input current. the output current output is controlled by a varying electric field. |
| State three operating advantages of FETs over bipolar type of transistors. | FETs do not have a thermal runaway as the temperature of the device increases. FETs have less voltage loss in a circuit than a BJT. FETs have higher input resistance. |
| Where FETs sad to be unipolar? | FETs are unipolar because working current flows through only one type of semiconductor material. |
| What are the two main types of FETs? | There are two types of FETs MOSFET and JFET. |
| Draw the schematic symbol and identify the leads of an N-channel and a P-channel JFET. | see Drawing there is no n-type picture on the |
| The action of a P-channel JFET is complementary to that of an N-channel JFET. what does this mean? | With N-channel and P-channel being complementary means that they operate the same but the currents and voltages are reversed. |
| What are the normal polarity of the drain and gate with respect to the source of an N-channel JFET? | A positive Vpp that is fixed with supply voltage is connected between drain and source this allows for current to flow between source and drain. A negative variable Vgg with supply is connected between the source and the gate |
| Why are JFETs classified as normally on devices? | This is because the JFETs allow full current to pass between the source and drain when the gate circuit is not activated. |
| In a JFET circuit, what gate-to-source biasing connection is normally used to prevent gate current flow? | A JFET gate is reversed-biased to prevent gate current flow. |
| Briefly explain how current flow thought an N-Channel JFET is controlled. | Because of the negative voltage at the gate, this allows resistance to increases which causes current flow to decrease. A positive fixed voltage at the supply will allow the current to flow |
| What is meant by the term pinch-off as it applies to a JFET circuit? | When a gate voltage goes negative the depletion zones will pinch off allowing current flow to stop between the drain and the source. |
| In a JFET circuit, why is the source current equal to the drain current? | Because the gate-source junction is operating in reverse bias there should be no current flows through it. This means that all current from the drain goes to the source. Making source current equal drain current. |
| What is the basic difference in construction between a JFET and a MOSFET? | The main difference between MOSFET and JFET is that a MOSFET gate has no electric contact with drain and source. |
| Draw the schematic symbol and identify the leads of an N-channel depletion type MOSFET. | get drawing see drawing |
| Why is the channel drawn as a solid line on this symbol? | The solid line is to represent the circuit between the source and the drain, which is normally complete and that the device is normally on. |
| What can this MOSFET withstand a positive voltage at the gate without damage? | The gate can withstand positive voltage because it is insulated. |
| What happens to the drain current flow when a positive voltage is applied to the gate? | The drain current flow increases and the channel becomes more conductive because there is a positive voltage at the gate. |
| What happens to the drain current flow when a negative voltage is applied to the gate? | When there is a negative voltage at the gate, the drain current flow decreases and the channel becomes less conductive. |
| Draw the schematic symbol and identify the leads of an N-channel enhancement type MOSFET. | a picture |
| Why is this channel drawn as a broken line on this symbol? | The line is broken because the device is normally off until there is proper gate voltage on the gate and to tell that there is an open between the source and drain. |
| What happens to the drain current flow when a positive voltage is applied to the gate? | The positive voltage at the gate has to get bigger until the threshold voltage can be applied which lowers the resistance and the drain current flow increases to saturation. |
| What happens to the drain current flow when a negative voltage is applied to the gate? | When the Vgs is a negative value or zero, there is no drain current flow and the device is off. |
| Explain why MOSFETs can be damaged by static charges. What special precautions is often taken for the packaging and shipping of MOSFETs? | Since the insulation layer is very thin it is very sensitive to any high voltage which static charges are high voltages. You need to keep MOSFETs in static protection packages or have their leads shorted together. |
| Explain how built | in Zener diodes can be used to protect MOSFETs against static charges. - The Zenner diode averts the current to protect the MOSFET. |
| Why should an analog ohmmeter not ordinarily be used for testing MOSFETs? | The analog ohmmeter is not to be used because it destroys the fragile oxide insulation. |
| In what way is the unijunction transistor not like a true transistor? | Unijunction transistors do not amplify. |
| State the basic function of a unijunction transistor. | The Unijunction transistor functions as a voltage-controlled switch. |
| Draw the schematic symbol and identify the leads of a standard N-type unijunction transistor. | see picture |
| In what way is the UJT symbol different from that of a JFET symbol? | The slant of the arrow is what makes the UJT different from an N-channel JFET. |
| To what junction of the UJT is the input signal applied? | You would put the input signal between base 1 and the emitter. |
| Assume a variable positive voltage is applied to the emitter of an N type UJT. describes what happens as this voltage is increased from zero. - | When you apply a positive voltage to a UJT it will hit peak voltage then start decreasing but at the peak, it starts emitting current from the emitter which switches to a forward-biased diode |
| You would get negative resistance because the transistor would be turned off. | |
| Briefly explain how a phototransistor operate to control current. | Light hits a lens opening in the transistor package which creates a current flow that turns the transistor on. |
| Draw the schematic symbol and identify the leads of a three-lead NPN photo transistor. | get a picture. |
| Why is the phototransistor more sensitive to changes in light insensitive that the photodiode? | Because of the use of transistors, the base current is higher which causes a higher output current at the emitter. |
| State the function of a power supply. | The function of a power supply is to take the input voltage and convert it into the correct type and value that is need for the circuit. |
| State five functions that a transformer may be required to perform in its role as part of a power supply circuit. | 5 functions that transformers perform as a part of a power supply are, steps down voltages, supplies a variable ac voltage, steps up voltages, electrically separates and isolates primary circuit from the secondary circuit, and supplies separate voltages t |
| Explain what is meant by the term rectification as it applies to a power supply. | Rectification is the process of changing DC to AC in a power supply circuit it also helps define which type of rectifier circuit it is full-wave or half-wave. |
| What electronic device is commonly used as a rectifier in power supplies? | The most common electric device in a rectifier circuit is the diode. |
| Compare half-wave and full-wave rectifier circuits with regard to the value and amount of pulsation of the dc output voltage. | Half wave rectifier circuits have dc voltage stops because it's only a half of a pulse and at frequency. Full-wave rectifier circuits have small ripples but no stoppages and is going to be at twice the supply frequency. |
| Compare a full-wave, center-tapped, bridge rectifier circuit with regard to: the number of diode voltage drops along the path from the transformer to the load. | The center-taped rectifier circuit has one voltage drop. The bridge rectifier circuit has two voltage drops. Full-wave rectifier circuits have two voltage drops. |
| The amount of reverse voltage that the diodes must withstand. | Center-taped rectifier circuits have to deal with twice the reverse voltage. |
| State two advantages of a three-phase, half-wave rectifier over a single-phase, full-wave rectifier | The three-phase half-wave rectifier circuit has two advantages less ripples and higher average voltage output than a single-phase full-wave rectifier circuit. |
| How many diodes are required for a three-phase, full-wave bridge rectifier? | Six diodes are required for a three-phase, full-wave bridge rectifier circuit. |
| What type(s) of transformer or alternator system(s) can a three-phase bridge rectifier be operated from? | You can use wye or delta systems to operate a three-phase bridge rectifier. |
| Explain what is meant by the term filtering as it applies to a power supply. | Filtering is used in power supplies to smooth out the ac ripple to make a purer dc waveform. |
| Name two electric devices commonly used as filters. | The two most common electronic devices is a capacitor connected in parallel and choke connected in series with the load along with a capacitor. |
| State three precautions that should be observed when selecting, connecting, and testing filter capacitors. | Make sure you don't plug filtering capacitors in backward because they will explode. You must drain the charge from the capacitors before you assume the circuit is dead. There can be a shock risk when using high voltage and capacitors even when off. |
| Explain the difference between a regulated and an unregulated power supply. | The unregulated dc power supply does not deliver pure dc and changes with load. When you have a voltage regulator connected to a rectifier circuit this is called a regulated power supply. |
| What special overcurrent protection feature is built into most IC voltage regulators? | The integrated circuit regulator has an internal thermal shutdown circuit that helps the chip from getting overheated due to a short circuit or overload. |
| What are dc-to-dc converters used for? | DC to DC converters are well regulated and are used to change voltage levels in dc. |
| What is the main advantage of using a voltage-multiplier circuit? | A voltage multiplier is cheaper than a step transformer. |
| What is one limitation of the voltage multiplier circuit? | The main limitation is the fact that there is very poor voltage regulation in a voltage multiplier circuit. |
| Explain the principle of operation of a switching power supply. | Switching the power supply you chop the unregulated dc at a high rate, then you use it to reconstruct the dc signal for the output load. |
| What are the two main advantages of switching power supplies over conventional linear power supplies? | The two main advantages are more output for the amount of input and it is more efficient by 85 percent. |
| What is the main disadvantage encountered with switching power supplies? | The main disadvantage is the RF noise generated by the switching network. |
| In what way is the atomic structure of all pure semiconductor crystals similar? | All pure semiconductors crystals have the same number of valence electrons in the outer valence shell. |
| What's the most common semiconductor material used in making electronic components? | Silicon is the most common semiconducting material used today. |
| What is the starring of outer orbit electrons in semiconducting materials called? | The name for the outer sharing of electrons is called a covalent bond. |
| What effect does this have on the resistance of the semiconductor? | They have a crystal structure because the semiconductors are poor conductors of electricity at room temperature. |
| Explain the process involved in forming an N-type semiconductor material. | For an N-type semiconductor, you need a dopant element to recreate a free electron. This free electron will help move current. Arsenic is an example of a dopant element. Any element can be used as long as It has five electrons in its outer ring. |
| Explain the process involved in forming a P-type semiconductor material? | For P-type semiconductors, you need a dopant element with three electrons in the outer ring. This creates a hole that when it combines with a silicon alloy and electricity creates a positive ion. Current moves through the holes against the flow of ions. |
| In what way is current conducted through an N-type material? - | Because of the free electron in the dopant element in an N-type semiconductor they can conduct electricity, It is the donor impurity that will allow for the current to flow through the diode. It will also create no depletion zone which will make the flow |
| In what way is current conducted through a P-type material? | On a P-type semiconductor, the holes created by the dopant will allow the flow of current because the free electrons will block certain holes as they move through the semiconductor. The current will equal the amount of free electrons moving through the ho |
| Compare the way forward and reverse bias affect the selection region and the function of a PN-junction diode | When you have a forward bias it will eliminate the depletion region. This will allow the diode to pass current. With reverse bias, the depletion area grows, so it can not pass current. |
| What determines whether a diode is forward or reverse biased? | The bias direction is based on the dc voltage polarity when applied to a diode. |
| Under what conditions is a diode considered to be connected in forward bias? | When the voltage applied to the diode is positive on the p side of the diode with respect to the n side of the diode. |
| Compare the amount of froward bias voltage it takes to turn on a germanium and silicon diode. | -It takes less voltage to turn on a germanium (0.2v) diode than silicon (0.7v) one. |
| When will a silicone diode avalanche? | The silicon diode will avalanche when you reach the peak inverse voltage rating in reverse bias. |
| Which lead end of a cylinder shaped diode is nearest to the identification band? | The cathode end is the closest to the band. |
| State three ways in which diodes are commonly rated. | Thermal rating, maxim current rating in the forward bias, and reverse maximum peak inverse voltage. |
| A diode is tested using an ohmmeter. What readings would indicate that the diode is not defective? | You will have low resistance reading in forward bias and a high resistance reading in reverse bias. |
| What is the purpose of a rectifier diode? | The purpose of a rectifier is to help convert alternating current into direct current. |
| What is the purpose of a circuit control diode? | The purpose of a circuit control diode is used to direct and control the current in one direction. |
| What is the purpose of a clamping or despiking diode? | The purpose of a clamping or despiking diode is to protect a circuit from surge currents or spikes and is connected in reverse bias to stop off switch spikes to the circuit. |
| Explain the operating principle of a varicap or varactor diode. | The operating principle behind the Vericap diode is that as reverse bias voltage increases capacitance decreases because the depletion area has increased or shrunk in width depending on the diode used. |
| In what way is the operation of a Zener diode different from that of a conventional diode? | A Zener diode in reverse direction breakdown voltage is lower than a regular diode. This allows for the Zener diode to have current-conducting in the reverse direction. |
| What is an LED specifically designed to do? | An LED is designed to light up when current is passed through it. It is also known as a Light-emitting diode. |
| How is an infrared emitting diode different from a conventional light-emitting diode? | The main difference between an IRED and a LED is that the IRED emits Infrared light which the human eye cannot pick up but in some cases, we may be able to feel the heat of the IRED. |
| What type of light beam is emitted from a laser diode? | A single Frequency light beam is emitted from a laser diode. Depending on the type of laser diode you could get infrared light. |
| Under what conditions is a photodiode designed to conduct current? | A photodiode will conduct current when it is in reverse bias mode. The light will become brighter when there is a reverse current that is increasing. |
| Name the three major components of a fiber-optic cable system? | You need a transmitter, which can be LED IRED or laser diode, optical fiber, and a receiver, which is a photodiode that accepts the light pulses then converts back to electrical forms. |
| short dc | zero or ol |
| open dc | source voltage |
| what is the most common way to bust a circuit? | shorting it |
| Anode | Positive electrode |
| Cathode | Negative electrode |
| P-type semiconductor | removes depletion zone a semiconductor that employs positively charged "holes" in the valence band as the charge carriers has three valence electrons |
| N-type semiconductor | a semiconductor that employs negatively charged electrons in the conduction band as the charge carriers |
| Forward biased diode | electrons flow through the diode little to no depletion zone. |
| Reverse biased diode | diode blocks the current depletion zone widens |
| bc battery may be backward | |
| how to test a forward bias diode | positive on anode negative on cathode should read low resistance or just use diode mode should read 0.7 volts |
| How to test a reverse bias diode | positive on cathode negative on anode should read high resistance. just use diode mode should read OL |
| 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 turn the light on. the amount of scattering on free electrons in the photoconductive cell which contacts the semiconductor substrate that enhances the resistance. |
| 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 a& collector voltage will be Vcc. The transistor will be at |
| 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. |
| 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. |
| State two ways practical applications for SCR and Triac circuits. | The two practical applications for an SCR and a Triac circuits are robot control and manipulation, control of motors light and heat control. |
| In what way is the operation of thyristors different from that of a transistor | The operation of a thyristor is different from that of a transistor they have excellent heat dissipation qualities and highly efficient means of switching heavy loads. |
| Compare the operation of SCR With that of conventional diode. | The operation of an SCR can only conduct in only one direction or better known as the SCR must be forward-biased from anode to the cathode for current conduction. |
| What does the regenerative latching action of an SCR refer to? | Regenerative latching SCR refers to the ability of the SCR to continue to conduct from anode to cathode even if the gate to the cathode is forward biased voltage is removed. |
| Why can an SCR switch large amounts of power and very efficiently? | An SCR can switch large amounts of power efficiently because low power loss in the device, when it is off it does not draw much current. |
| Define the term holding current as it applies to an SCR. | Holding current is the amount of current required for the SCR to keep conduction up. |
| When an SCR switch circuit is operated from an AC Source what type of output is obtained? | The maximum output delivered to the load is 50% and the shape of it is a half-wave pulsing DC waveform. |
| The output to the load of an AC operated SCR can be doubled by the addition of what type of circuit? | If you add a bridge rectifier their circuit you can double the output load of an AC operated SCR circuit. |
| Explain the term phase shift as it applies to the control circuit of an SCR. | The term phase shift in the control of an SCR means the voltage applied to the gate must be shifted out of phase with the voltage applied to the anode. |
| An SCR circuit operated from an AC Source uses the pulses produced by a UJT oscillator to trigger at the gate. Why are the pulse is produced by the UJT considered to be Phase shifted? | The pulses produced by the UJT is considered to be phase-shifted because the pulses are used to provide a trigger for the gate of the SCR, so it can be fired at any time. |
| An ohmmeter is used to check the resistance between the means of an SCR. Assuming the SCR is not effective what resistance reading should be ? (anode and cathode) | Anode to cathode you have high resistance in both directions. |
| An ohmmeter is used to check the resistance between the means of an SCR. Assuming the SCR is not effective what resistance reading should be ? (gate and cathode) | Gate and cathode you have low in forward bias in the high in reverse bias. |
| An ohmmeter is used to check the resistance between the means of an SCR. Assuming the SCR is not effective what resistance reading should be ? (gate and anode) | Gate and anode you have a high in my resistance in both directions. |
| when operated from an AC Source why is the Triac more efficient than an SCR? | The reason why the Triac is more efficient than an SCR is that it can both halves of the waveform and also the output is ac. |
| The SCR has only one triggering mode. What is it? | The triggering mode for an SCR is at the start of the ac wave pulse. |
| State four possible modes of triac | The four triggering modes Triac are MT2 positive gate Positive, MT2 positive gate negative, MT2 negative gate positive, MT2 negative gate negative |
| Under what conditions will a diac conduct current? | The conditions diac will conduct current is is when the voltage across it reaches its rated break over voltage which means the diac latches on and remains in the conducting state. |
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