Circuit Design & Troubleshooting Flashcards
7 cards from real EETC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Circuit Design & Troubleshooting flashcards as text
What is the function of a bypass capacitor placed close to an IC's power supply pin?
Answer: To filter high-frequency noise on the supply rail and provide instantaneous current to the IC
Bypass capacitors (typically 0.1µF ceramic) suppress high-frequency noise on the supply line and act as a local charge reservoir for fast current transients.
A technician measures the voltage across each component in a series circuit: R1=5V, R2=7V, R3=4V. What should the supply voltage measure?
Answer: 16V
By Kirchhoff's Voltage Law, the supply voltage equals the sum of all individual voltage drops: 5 + 7 + 4 = 16V.
Which oscilloscope measurement is most useful for diagnosing a phase shift between input and output signals in an amplifier?
Answer: Lissajous figure (X-Y mode)
An oscilloscope in X-Y mode displays a Lissajous figure whose shape (circle, ellipse, or line) directly indicates the phase relationship between two signals.
What is the primary cause of skin effect in AC conductors, and how does it affect circuit design at high frequencies?
Answer: Current concentrates near the conductor's surface, increasing effective resistance
At high frequencies, eddy currents force AC current to flow near the conductor surface, reducing effective cross-sectional area and increasing resistance.
In a transistor biasing circuit, if the base-emitter junction measures 0V instead of the typical 0.6–0.7V, what has most likely occurred?
Answer: The transistor's B-E junction is open (failed)
A functional silicon BJT base-emitter junction drops approximately 0.6–0.7V; 0V across this junction indicates the junction is open (no current path exists).
When designing a circuit for operation in an environment with significant vibration, which capacitor type should generally be avoided?
Answer: Large electrolytic capacitors with leads
Large through-hole electrolytic capacitors with leads are susceptible to mechanical failure from vibration fatigue at the lead-body junction.
A technician is troubleshooting a switching power supply that produces output voltage but with excessive high-frequency noise. What is the most likely component to inspect first?
Answer: The output filter inductor and capacitors
Excessive high-frequency noise on the output of a switching supply typically indicates a failed or degraded output filter capacitor or a saturated output inductor.