Can You Solve This? Questions

AC/DC Problems

Battery Life: Given a battery of 9 volts, an internal resistance of 1 ohm, and a rating of 1.2 ampere-hours, how long will the battery last if connected to a load resistance of 8 ohms? Answer Capacitor Charging: An uncharged capacitor is the load on a switching circuit. The initial capacitor voltage is 0 V and the final capacitor voltage is 100 V. If the charging time constant is 1 millisecond, what is the capacitor voltage 1 millisecond after the charging begins? What is the capacitor voltage 2 milliseconds after the charging begins? Answer RC Lag Circuit: The source voltage is 1 V with a frequency of 1 kHz. The source is connected to a resistance of 1 kohm in series with a capacitance of 159 nF. What is the capacitor voltage and phase angle? Answer Series Resonance: An RLC series circuit has R = 2 kohms, L = 10 mH, and C = 12.2 nF. What is the voltage across the capacitor when the circuit operates at the resonant frequency? Answer Parallel Resonance: An RLC parallel circuit has R = 10 kohms, L = 5 mH, and C = 12.7 nF. What is the Q of the circuit at the resonant frequency? Answer

Active Filter Problems

Frequency Response: Sketch the frequency responses of these fourth-order low-pass filters with 3-dB cutoff frequency of 1 kHz: Butterworth, Chebyshev, and Bessel. Answer Step Response: Sketch the step responses of these fourth-order low-pass filters with 3-dB cutoff frequency of 1 kHz: Butterworth, Chebyshev, and Bessel. Answer Sallen-Key Low-pass Filter: Show the configuration of a low-pass Sallen-Key second-order filter. Answer Sallen-Key High-pass Filter: Show the configuration of a low-pass Sallen-Key second-order filter. Answer Bandpass Filter: Show the configuration of a bandpass Multiple-feedback filter. Answer

Bias

Base Bias: A base-biased transistor has a base resistor of 22 kohms, a collector resistor of 100 ohms, a dc beta of 100, a collector-supply voltage of 15 V, and a base-emitter voltage of 0.7 V. What is the collector current? The collector-emitter voltage? Draw the dc load and show the Q point. Answer Voltage-divider Bias: A voltage-divider-biased transistor has R1 = 10 kohms, R2 = 2.2 kohms, RE = 1 kohm, RC = 3.6 kohms, VBE = 0.7 V, and VCC = 10 V. What is the base voltage? The emitter voltage? The collector voltage? Answer Collector-feedback Bias: A transistor uses collector-feedback bias with RB = 10 kohms, RC = 100 ohms, dc beta = 100, VBE = 0.7 V, and VCC = 15 V. What is the collector current? The collector voltage? Answer Two-supply Emitter Bias: A circuit uses two-supply emitter bias with RB = 51 kohms, RE = 7.5 kohms, RC = 4.7 kohms, dc beta = 100, VBE = 0.7 V, VCC = 15 V, and VEE = -15 V. What is the base voltage? The emitter voltage? The collector voltage? Draw the load line. Answer MOSFET Bias: An n-channel enhancement-mode MOSFET has VGS = 5 V, VGSth = 2 V, RDSon = 500 ohms, RD = 1 kohm, VGSon = 5 V, IDon = 5 mA, and VDD = 15 V. What is drain current? The drain-source voltage? Answer

Communications

Decibels: Convert a power gain of 2000 to its decibel equivalent. Also, convert a decibel voltage gain of 65 dB to its numerical equivalent. Answer Difference Frequencies: A frequency mixer has inputs of 1.45 MHz and 1 MHz. What is the difference frequency? How is a spurious signal defined? Answer Thermal Noise: A communication receiver has a voltage gain of 100 dB and a bandwidth of 100 kHz. How much thermal noise does an input resistance of 5 kohms produce at the output of the amplifier? Answer Square-wave Harmonics: Describe the harmonics of a square wave. Answer Sawtooth Harmonics: Describe the harmonics of a sawtooth wave. Answer

Conversions

ASCII Code: Convert upper-case C to its ASCII equivalent. Answer Decimal to Binary: What is the binary equivalent of decimal 16,829? Answer Decimal to Hex: Convert decimal -3000 to its hex in 2's complement format. Answer Hex to Binary: What is the binary equivalent of hex B8F2? Answer Hex to Decimal: Convert hex FFFF to decimal. Answer

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