E7A Digital circuits: digital circuit principles and logic circuits; classes of logic elements; positive and negative logic; frequency dividers; truth tables
- E7A01 (C)
Which circuit is bistable? #card
- A. An AND gate
- B. An OR gate
- C. A flip-flop
- D. A bipolar amplifier
- E7A02 (A)
What is the function of a decade counter? #card
- A. It produces one output pulse for every 10 input pulses
- B. It decodes a decimal number for display on a seven-segment LED display
- C. It produces 10 output pulses for every input pulse
- D. It decodes a binary number for display on a seven-segment LED display
- E7A03 (B)
Which of the following can divide the frequency of a pulse train by 2? #card
- A. An XOR gate
- B. A flip-flop
- C. An OR gate
- D. A multiplexer
- E7A04 (A)
How many flip-flops are required to divide a signal frequency by 16? #card
- E7A05 (D)
Which of the following circuits continuously alternates between two states without an external clock signal? #card
- A. Monostable multivibrator
- B. J-K flip-flop
- C. T flip-flop
- D. Astable multivibrator
- E7A06 (A)
What is a characteristic of a monostable multivibrator? #card
- A. It switches temporarily to an alternate state for a set time
- B. It produces a continuous square wave
- C. It stores one bit of data
- D. It maintains a constant output voltage, regardless of variations in the input voltage
- E7A07 (D)
What logical operation does a NAND gate perform? #card
- A. It produces a 0 at its output only if all inputs are 0
- B. It produces a 1 at its output only if all inputs are 1
- C. It produces a 0 at its output if some but not all inputs are 1
- D. It produces a 0 at its output only if all inputs are 1
- E7A08 (A)
What logical operation does an OR gate perform? #card
- A. It produces a 1 at its output if any input is 1
- B. It produces a 0 at its output if all inputs are 1
- C. It produces a 0 at its output if some but not all inputs are 1
- D. It produces a 1 at its output if all inputs are 0
- E7A09 (C)
What logical operation is performed by a two-input exclusive NOR gate? #card
- A. It produces a 0 at its output only if all inputs are 0
- B. It produces a 1 at its output only if all inputs are 1
- C. It produces a 0 at its output if one and only one of its inputs is 1
- D. It produces a 1 at its output if one and only one input is 1
- E7A10 (B)
What is a truth table? #card
- A. A list of inputs and corresponding outputs for an op-amp
- B. A list of inputs and corresponding outputs for a digital device
- C. A diagram showing logic states when the digital gate output is true
- D. A table of logic symbols that indicate the logic states of an op-amp
- E7A11 (B)
What does “positive logic” mean in reference to logic devices?
- A. The logic devices have high noise immunity
- B. High voltage represents a 1, low voltage a 0
- C. The logic circuit is in the “true” condition
- D. 1s and 0s are defined as different positive voltage levels
