Examen EASA M4

Thermal runaway in a transistor is caused by. excessive heat causing maximum current flow. excessive heat causing minimum current flow. low heat causing minimum current flow.

An advantage of a common emitter is. it has high power gain. it is a voltage follower. it has high voltage gain.

What class of amplifier is biased at cut off?. C. B. A.

When testing a transistor with an ohmmeter, what is the resistance of the emitter/collector?. Low resistance both ways. High resistance one way. High resistance both ways.

A transistor at saturation has. low resistance. zero resistance. high resistance.

A capacitor-resistor coupled multistage amplifier lets. DC pass only. AC and DC pass to the next stage. AC pass only.

An oscillator operating at its natural frequency has feedback which is. 90 degrees out of phase. 180 degrees out of phase. in-phase.

Which mathematical operation is performed by a modulator amplifier?. Addition. Subtraction. Multiplication.

A JFET is. either of the above depending on resistance in the circuit. current sensitive. voltage sensitive.

Thermal runaway in a transistor refers to. high current flow when temperature decreases. ow current flow when temperature increases. high current flow when temperature increases.

Resistors and capacitors are used to couple stages of amplifiers so that. only DC can be applied. only AC can be applied. equal amounts of AC and DC can be applied.

An advantage of a FET when compared to a bi-polar transistor is. the switching time is quicker. the input resistance is higher. the input resistance is lower.

Where are decoupling capacitors used in digital circuits?. Between pins 1 & 8. n. Close to the positive pin. Close to the negative pin.

A Common Collector circuit has the following characteristics. Medium Voltage Gain, High Current Gain, Non-Inverted Output. Low Voltage Gain, High Current Gain, Inverted Output. Medium Voltage Gain, Low Current Gain, Inverted Output.

In a Common Emitter Amplifier RE is used for. load control. biasing. stabilisation.

The most suitable class of amplifier for a high fidelity radio transmitter is. B. C. A.

A transistor in Common Emitter mode gives. high voltage gain only. high current gain only. high power gain.

For a transistor in common emitter mode, the term Hfe indicates. the Voltage gain Vce/Vbe at Ib constant. the Power gain Pin/Pout. the current gain Ic/Ib at Vce constant.

In a differential amplifier the term "common mode voltage" means. output voltage with one input connected to common ground. output voltage with non-inverting input at 0 volts. output voltage when both inputs have equal voltages.

In an ideal current amplifier. input impedance must be low and output high. input impedance must be high and output low. both input and output impedances must be low.

In an ideal voltage amplifier. input impedance must be high and output impedance low. input impedance must be low and output impedance high. input impedance must be low and output impedance low.

The term ICE related to transistor in common emitter mode means. leakage current flowing between Collector and Emitter with Base open circuited. forward current between Collector and Emitter with Base connected to signal. leakage current between Collector and Emitter with Base connected to ground.

A common base amplifier has. high input and high output impedance. low input and high output impedance. low input and medium output impedance.

The emitter, base and collector currents in a common emitter circuit, follow ohm"s and kirchoff"s law, which is. Ie = Ic - Ib. Ib = Ie + Ic. Ie = Ib + Ic.

What are the ideal characteristics of an Op Amp?. Infinite gain, infinite input Impedance and infinite output impedance. Infinite gain, infinite input Impedance and zero output impedance. Low gain, infinite input Impedance and zero output impedance.

What gate does the following Boolean expression represent F = A.B.C. AND. OR. NOT.

What gate does the following Boolean expression represent F = A+B+C. NOR. OR. NOT.

In an integrated circuit, the components are mounted. by metal screws. by metal oxide film. by means of wires connecting them.

A non-inverting op-amp. has an inverting input and a non-inverting output. a non-inverting input connection only. has a non-inverting input and an inverting output.

In an operational amplifier, the two input waves are the same amplitude, same frequency, but exactly anti-phase. What would the output be?. Double. Zero. Half.

In the following Boolean algebra statement, which gate is described?. F = A + B + C. AND. OR. NOT.

In the Boolean algebra statement below, the gate described is F = A.B.C. NAND. AND. NOR.

Infinite gain, infinite input impedance and zero output impedance is characteristic of a. Class B amp. Class A amp. Op amp.

What is meant by a bistable circuit?. The circuit has 2 stable states and will stay in which one it is put. The circuit has 1 stable state and it can be negative or positive. The circuit has 2 stable states and will stay in both at the same time.

What does the output voltage of an op-amp depend upon?. The op amp bandwidth. The gain of the op-amp. The resistors in the circuit.

What type of gate is an OR gate with both inverted inputs and inverted outputs?. NAND gate. NOR gate. AND gate.

Diodes connected in parallel would act like an. an NAND gate. an AND gate. an OR gate.

The voltage supply to a Complimentary Metal Oxide Semiconductor (CMOS) integrated circuit must be. 0 V is 5 V DC. 3V to 18V DC. 3V to 15V AC.

How are the pins numbered on an op-amp IC?. from left to right from the dot. counter clockwise from the dot. clockwise from the dot.

On an integrated circuit the hole in the top left corner is pin 1. The pins are counted. clockwise. from left to right. anticlockwise.

A single integrated circuit Op Amp has how many pins?. 7. 8. 4.

A logic circuit with more than one gate will have. 2 or more outputs. one of 2 states of logic output. an analogue output.

A VLS IC has. more than 10,000 gates. less than 1000 gates. more than 1000 gates.

A momentary input at the reset input of a flip flop will. reset the true output to 0. clock in new data from the data inputs. reset the true output to 1.

Which type of flip flop has only 1 data input?. JK. D. RS.

When you use an op amp as a buffer it has. low input impedance and high output impedance. high input impedance and low output impedance. the same input an output impedance.

What is required for the switching of a monostable multivibrator?. One trigger pulse to both switch on and off. One trigger pulse to switch on and two trigger pulses to switch off. One trigger pulse to switch on and another to switch off.

An astable multivibrator is a. one which requires no input whatsoever. one which requires an input to switch on and off. free running vibrator.

Op amps use what power supply?. 26 VAC. 5-15 VDC. 26 VDC.

A device which has a high input impedance, low output impedance and high voltage gain is a. Op-Amp. Class A amp. Class B amp.

In an integrated circuit, the components are mounted by. a three dimensional process with no connections between them required. wires connecting them using conformal coating. metal oxide film etched onto the surface.

In an integrated circuit, the components are inserted. automatically. by doping in successive layers. manually.

In an electronic circuit with an operational amplifier connected in the push-pull configuration, the circuit. utilizes both sides of the input signal. decreases impedance. blocks half of the input signal.

Pin 3 on an op-amp has a + symbol. This designates. positive input DC pin. non-inverting input. positive offset null.

An integrated circuit is manufactured by. doping impurities into layers of intrinsic material. etching copper tracks onto an insulating board. computer hardware, which use individual circuits on ribbon.

A monostable vibrator. is switched on by a trigger pulse then within a pre-set time will eventually return to its original state. uses a trigger pulse to turn on and the same pulse to turn off. uses one pulse to turn on and another to turn off.

The negative feedback for an op-amp integrator is connected across a. resistor. inductor. capacitor.

The input resistance to an inverting op-amp is 100 Ohms. The feedback resistance is 100 kilohms. What is the amplifier gain?. 1000. 1/1000. -1000.

In an integrated circuit, active, passive and connecting components are. connected by fine gold wires. mounted on the outside of the solid block. embedded within the solid block.

When compared to a system that is constructed on one board, a modular system using Printed Circuit Boards (PCBs) is. harder to fault find. more expensive for spares. easier to fault find.

A Printed Circuit Board (PCS) is constructed of a plastic laminate which has bonded to one or both sides. a thin sheet of copper. various thicknesses of copper. a thick sheet of copper.

How is a PCB protected after manufacture?. By conformal coating. With non-conductive varnish. With wax.

A multi-layer PCB has. two or more layers on one or both sides. one layer on either side. two or more layers connected in serie.

When removing a microprocessor. ensure the power is OFF to avoid static discharge. no damage is done by static discharge. considerable damage can be done by static discharge.

On a PCB, a decoupling capacitor is used to get rid of transient currents between which points?. The electronic circuit and the aircraft ground. The negative rail and the rest of the circuit. Interspaced along the circuit.

A decoupling capacitor in a PCB is used to. minimise transient currents. pass DC only. pass AC only.

What is the base material of a PCB?. Insulator. Semiconductor. Conductor.

In a printed circuit board , the surface resistance testing is. insulation resistance between adjacent printed conductor. the resistance between the tow inductors. between the board and the conductor.

What are printed circuit boards made of?. Fibreglass board coated with copper in which circuits are etched. Synthetic resin board etched with copper. Matrix board with components soldered on.

The output of a tachogenerator is. proportional to speed of rotation. proportional to position. proportional to acceleration.

AC power to a synchro system is supplied to. torque transmitter only. both the torque receiver and torque transmitter. torque receiver only.

A differential synchro. can be used as either a transmitter or a receiver. can only be used as a receiver. can only be used as a transmitter.

A resolver has. 3 coils on the rotor and 2 coils on the stator. 2 coils on the rotor and 3 coils on the stator. 2 coils on the rotor and 2 coils on the stator.

The "null" point on a control synchro is when the two rotors are. wired in series. at 90° to each other. parallel to each other.

The rotor of a desynn indicator is. an electromagnet. a permanent magnet. an AC magn.

The position feedback from a potentiometer is. anti-phase. in phase. 90 degrees out of phase.

A differential synchro has. single phase stator, 2 phase rotor. 3 phase stator, 3 phase rotor. 3 phase stator, single phase rotor.

When a servomotor has stopped, the rate feedback from a tachogenerator is. maximum and in phase. maximum and anti-phase. zero.

A tachogenerator is usually used for. angular feedback. rate feedback. position feedback.

Differential synchros have. a transmitter and a receiver. a transmitter only. a receiver only.

In a torque synchro system, the power supply is connected to. the rotor windings of both the transmitter and receiver. the stator windings of the transmitter. the rotor windings of the transmitter only.

To reduce overshoot errors in a synchro. the gain of the amplifier is increased. the system will have velocity feedback. the system will have position feedback.

A synchro transformer is used to. add the output of two synchro transmitters. derive an error voltage from a synchro transmitter signal and a shaft position. obtain a 26 volt AC reference.

Reversal of the complete power to a torque synchro system will. displace the receiver rotor by 180o. cause reverse rotation of the receiver rotor. have no effect.

The power supply to a torque synchro system is. AC or DC. AC. DC.

An open loop system is one which has. no direct feedback loop. rate feedback loop. position feedback only.

Mechanical friction in a servo results in. increased inertia. increased damping. reduced gain.

The position feedback signal is. phase advanced by 90° with respect to the input signal. in phase with the input demand signal. in anti-phase with the demand signal.

A servo system that overshoots and oscillates is. under damped. over damped. critically damped.

The power supply to a torque synchro system is connected to. the transmitter rotor only. the transmitter stator. the transmitter and receiver rotors.

In a toroidal resistance transmitter indicator system, the power supply is connected to. the resistor slab. the rotor. the brushes.

When a servo has reached its null and stopped, the velocity feedback is. maximum and anti-phase. maximum and in phase. zero.

The primary purpose of rate feedback in a positional servo system is to. ensure system linearity. prevent excessive overshoot. ensure minimum response time.

In an AC rate servo, a steady input will result in the servomotor. rotating to a new datum position. rotating at a constant speed. oscillating about a new datum.

In a torque synchro that includes a differential synchro the power supply is connected to. all three rotors. the transmitter and receiver rotors only. the transmitter rotor only.

A differential synchro rotor has. three windings. two windings. one winding.

In a resolver synchro the stator windings are electrically displaced by. 90°. 180°. 120°.

A resolver synchro output is obtained from a rotor with. two coils at 90°. one single coil. three coils at 120°.

In a speed control servo system (rate control), the purpose of the tachogenerator is. to make the velocity proportional to servo demand. to make the deflection proportional to servo demand. to make it run at constant speed.

The rotor of a torque synchro indicator is. supplied with an excitation voltage. connected in series with the transmitter stator coil. short circuited.

To increase the output of a servo amplifier, it is necessary to. reduce the tacho feedback. increase the position feedback. increase the tacho feedback.

Angular displacement of the control coils with respect to the reference coils in a two phase induction motor are. 90°, 270°. 0°, 180°. 90°, 120°.

A servomotor having only a tachogenerator as a feedback device will. vary its speed with input error voltage. null out at a position dependant upon input error voltage. have a constant speed for any given input voltage.

The null position of a torque synchro system is when. the TX and TR rotors are parallel to each other. the TX and TR rotors are 90° to each other. the TX and TR rotors are 120° to each other.

An AC tachogenerator stator has. two windings 180° apart. three windings 120° apart. two windings 90° apart.

When the rotor of an AC tachogenerator is stationary, the rotor has. no magnetic fields. no circulating currents. low circulating currents.

A closed loop servomechanism. must only have position feedback. must have both position and velocity feedback. can have either position or velocity feedback.

In a control synchro system the power supply is connected to the. transmitter and receiver rotors. transmitter rotor and amplifier. receiver rotor and amplifier.

Velocity feedback. opposes the demand input. assists the demand input. prevents dead space errors.

An increase in velocity feedback will. decrease the speed the load moves. have no effect on speed. increase the speed the load moves.

Rate feedback can be obtained from a. tachogenerator. synchro. potentiometer.

Positional feedback can be obtained from a. synchro. potentiometer. tachogenerator.

The "null" point in a control synchro is when the two rotors are. at 90° to each other. wired in series. parallel to each other.

In a control synchro the stator current ceases to flow when the. CT rotor is at null. power is removed. two rotors are aligned.

In a rate servo (speed control) the signal into the servo amplifier is. input voltage plus position feedback voltage. input voltage plus tachogenerator output. input voltage minus tachogenerator output.

To reduce oscillations about a demand position. the amount of velocity feedback would be increased. the amount of velocity feedback would be decreased. the amount of position feedback would be increased.

Positive feedback applied to a servomechanism. increases the response of the system. opposes the demand signal. decreases the response of the system.

A differential synchro rotor consists of. two windings at 90° apart. one winding parallel to the transmitter rotor. three windings at 120° apart.

A differential synchro transmitter used for addition has. the TDX S1 and S3 connections cross connected to the TX. the TDX S1 and S3 connections cross connected to the TR. the TDX R1, R3 and S1, S3 connections cross connected to the TX.

Differential transmitters are used to. add or subtract two electrical signals. add or subtract a mechanical signal to an electrical synchro signal. increase the operating speed of the synchro receiver.

When resolving a Cartesian input to a Polar output. the outputs are two voltages. the inputs are a shaft angle and a voltage. the inputs are two voltages.