Fundamentals of Electronics Flashcards

In a full-wave bridge rectifier, how many diodes are required?

Answer: 4

A full-wave bridge rectifier uses 4 diodes arranged so that current flows through the load in the same direction for both AC half-cycles.

What is the primary advantage of using a switching power supply over a linear power supply in biomedical equipment?

Answer: Higher efficiency and smaller size

Switching power supplies operate at high frequencies allowing smaller transformers and capacitors, resulting in higher efficiency (often >85%) and reduced size/weight.

A Wheatstone bridge is balanced when:

Answer: R1/R2 = R3/R4

The Wheatstone bridge is balanced (zero galvanometer current) when the ratio of resistances in each arm are equal: R1/R2 = R3/R4.

In digital logic, what is the output of a NAND gate when both inputs are HIGH?

Answer: LOW

A NAND gate outputs LOW only when all inputs are HIGH; it is the complement of an AND gate.

What phenomenon occurs when an AC signal causes a transistor to conduct during only part of the input cycle in Class B amplification?

Answer: Crossover distortion

Crossover distortion occurs at the zero-crossing point in Class B push-pull amplifiers due to the transistor's 0.6V threshold voltage.

A 12-bit ADC with a 5V reference voltage has a resolution of approximately:

Answer: 1.22 mV

Resolution = Vref / 2^n = 5V / 4096 ≈ 1.22 mV per step for a 12-bit ADC.

In a biomedical instrumentation amplifier, the primary purpose of the input stage with matched resistors is to:

Answer: Achieve very high CMRR and input impedance

The matched-resistor input stage of an instrumentation amplifier maximizes CMRR and provides high input impedance to avoid loading the signal source.