Logic Circuits (5.5)

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Questions and Answers

What is the primary building block of logic circuits?

Diodes

Resistors

Logic gates (correct)

Integrated circuits

Which Boolean expression represents the OR operation for two inputs A and B?

X = A * B

X = A + B (correct)

X = A - B

X = A / B

When will the output X = 0 in an OR operation with inputs A and B?

When A = 1 and B = 0

When A = 0 and B = 1

When A = 1 and B = 1

When A = 0 and B = 0 (correct)

How does the OR operation treat the addition of two 1s?

It produces a 1 Signup and view all the answers

What is an example of a complex combination of logic circuits?

Integrated circuit Signup and view all the answers

If X = A + B + C, when will X output be 1?

When at least one input is 1 Signup and view all the answers

In Boolean algebra, how is the value '1' defined?

As a true condition Signup and view all the answers

What logic output is produced when both inputs of an OR gate are zero?

0 Signup and view all the answers

Which of the following devices can represent binary quantities by having only two operating states?

Thermostat Signup and view all the answers

In a digital system, what does an open switch represent when defining binary states?

Binary 0 Signup and view all the answers

Which of the following options accurately describes a closed switch in binary representation?

Active state represented by the number 1 Signup and view all the answers

What binary representation is typical for a punched hole in paper?

Binary 1 Signup and view all the answers

Which logic element operates based on conditions of energised and de-energised states?

Relay Signup and view all the answers

Which of the following correctly matches a device with its binary state representation?

Light bulb: on - off Signup and view all the answers

Which device is NOT typically used to represent binary quantities?

Buzzer Signup and view all the answers

What is the binary value for a transistor when it is in a saturated state?

Binary 1 Signup and view all the answers

What is the primary function of a buffer in a logic circuit?

To mirror the input at the output Signup and view all the answers

Why are the NOR and NAND gates classified as universal gates?

They can produce any basic operation through combinations Signup and view all the answers

What happens when two inverter gates are connected in series?

They create a buffer that cancels each other out Signup and view all the answers

Which of the following statements about a buffer is true?

It can serve as an impedance-matching device Signup and view all the answers

What is the output state of an XNOR gate when only one input is HIGH?

LOW Signup and view all the answers

In the context of logic gates, what is meant by 'active-LOW' state?

The output is LOW for certain combinations of inputs Signup and view all the answers

Which type of amplifier is commonly referred to as an emitter follower?

Common collector amplifier Signup and view all the answers

What limitation do non-inverting gates have compared to universal gates?

They cannot produce an invert operation Signup and view all the answers

What is the output expression for a logic circuit with inputs A, B, and C where the output is derived from an AND gate and an OR gate?

X = A.B + C Signup and view all the answers

Which of the following accurately describes the construction of a three-input AND gate?

Using two AND gates connected together Signup and view all the answers

In the expression X = C + A.B, which operation is performed last?

OR operation Signup and view all the answers

Which Boolean operation serves as a fundamental building block for digital systems?

AND Signup and view all the answers

What is the role of the OR gate in a combined logic circuit?

To combine multiple inputs and provide a maximum output Signup and view all the answers

What does simplistically combining gates imply about the complexity of a logic circuit?

All circuits can be built from basic AND, OR, and NOT gates Signup and view all the answers

When two logic levels are connected, what is usually assumed about their interaction?

The higher level will provide a signal to lower level Signup and view all the answers

If an additional NOT gate is included in a logic circuit, what will it do to the input signal?

Reverse the input signal Signup and view all the answers

What supplies the AC ESS BUS when the nose landing gear is compressed?

STATIC INVERTER Signup and view all the answers

What happens if AC BUS 1 and 2 are lost and the RAT does not extend?

The FAULT light on the EMERGENCY ELECTRICAL POWER panel turns red Signup and view all the answers

How is the RAT manually extended to power the emergency generator?

By pressing the guarded MANUAL ON on the EMER ELEC PWR panel Signup and view all the answers

What is the purpose of the emergency generator operational test?

To assess the emergency generator parameters and network supply Signup and view all the answers

What must be done to pressurize the blue hydraulic system during the emergency generator test?

Activate the BLUE PUMP OVERRIDE Signup and view all the answers

How does a scavenge pump differ from normal fuel pumps?

It can run dry for a period of time Signup and view all the answers

What is the primary function of the Centre Wing Tank (CWT) Scavenge Pump?

To remove residual fuel from the CWT Signup and view all the answers

What must be checked on the ECAM display during the emergency generator test?

Generator parameters Signup and view all the answers

Study Notes

Learning Objectives

Identify common logic gate symbols and their corresponding truth tables and circuits.
Understand applications of logic circuits within aircraft systems and schematic representations.
Interpret logic diagrams for effective communication and analysis.
Describe the operation and functions of latches and clocked flip-flop logic circuits.

Boolean Logic

Digital systems process information in binary form, using devices with two operating states (e.g., switches, sensors).
Binary representation can include devices such as light bulbs, diodes, relays, and transistors, signaling either 0 or 1.
Logic circuits are formed by combining multiple logic gates, breaking down complex operations into simpler ones.
Basic logic gates include OR, AND, and NOT, forming the fundamental building blocks for digital systems.

OR Gates

The OR operation outputs a logic 1 whenever any input is 1; output is 0 only when all inputs are 0.
Boolean expression for OR operation: X = A + B, signifying the logical addition where 1 + 1 = 1.
A three-input OR operation can be represented as X = A + B + C.

Combining Gates

Complex gates can be constructed from multiple smaller gates; e.g., a three-input AND gate can use two existing AND gates.
Outputs and expressions can be combined, e.g., X = A · B + C, where order does not affect the result.

Universal Gates

NAND and NOR gates are considered universal gates due to their ability to replicate all other basic logic functions.
Non-inverting gates (AND, OR) lack the versatility to perform logical inversion.

Buffers

Buffers are single-input devices that replicate inputs at their outputs with a gain of 1.
Useful for impedance matching in circuits; a common implementation is the common collector amplifier, or emitter follower.

Operational Context in Aircraft

If both AC buses are lost, a Fault indicator activates on the Emergency Electrical Power panel.
Manual extension of the ram air turbine (RAT) is required to power the emergency generator.
The emergency generator must be tested under specific conditions, ensuring the blue hydraulic system is pressurized.

Centre Wing Scavenge Pump Operation

Scavenge pumps operate at the lowest point of fuel tanks to extract residual fuel.
Unlike regular pumps, scavenge pumps are designed to run dry without damage.
The Centre Wing Tank (CWT) scavenge pump operates automatically, removing fuel that the main pumps cannot extract.

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Description

This quiz covers the identification of logic gate symbols, their applications in aircraft systems, and interpretation of logic diagrams. Students will explore the operation and use of latches and clocked flip-flop circuits. Enhance your understanding of digital techniques in electronic instrumentation.