Karnataka II PUC Electronics (KSEAB) case studies
Karnataka II PUC Electronics (KSEAB) · Put your knowledge to work in context.
Electronics is a two-year elective offered in Karnataka's Pre-University Course and examined at the end of the second year by the Karnataka School Examination and Assessment Board (KSEAB). Candidates typically take it alongside Physics, Chemistry and Mathematics as a route into B.E./B.Tech electronics, electrical, instrumentation or computer science programmes, or into diploma and technician roles. The Karnataka II PUC Electronics (KSEAB) case studies are 5 cases and about 4,460 words.
1Ripple Twice the Design Value in a Capacitor-Filtered Bridge Rectifier
A trainee at a repair shop builds a 12 V, 200 mA bench supply. The transformer secondary is 12 V rms, the bridge uses four 1N4007 diodes, and the reservoir is a 2200 µF/25 V electrolytic feeding a load that draws a steady 200 mA.
898 words, about 4 min2Relay Driver That Will Not Pull In: Base Drive Versus Transistor Gain
A student interfaces a 12 V relay to a 3.3 V microcontroller GPIO using an BC547 in common-emitter configuration. The relay coil measures 400 Ω, so the collector current needed in saturation is about (12 − 0.2)/400 ≈ 29.5 mA.
842 words, about 4 min3555 Astable That Will Not Give 50 % Duty Cycle
A student builds a 555 astable to clock a logic circuit: RA = 10 kΩ from Vcc to discharge pin 7, RB = 10 kΩ from pin 7 to the threshold/trigger pins, C = 100 nF ceramic (±10 %) from the threshold pin to ground, Vcc = 5 V, NE555 (bipolar), pin 4 tied to Vcc, pin 5 left open, no decoupling capacitors. The brief asks for a 1 kHz square wave with 50 % duty.
909 words, about 5 min4Op-Amp Output Collapses at 20 kHz: Slew Rate or Gain-Bandwidth?
A student builds an inverting amplifier with a 741 op-amp: Rin = 1 kΩ, Rf = 100 kΩ, so the intended gain is −100, powered from ±15 V. The input is a 0.1 V peak sine from a signal generator, and the expected output is 10 V peak.
911 words, about 5 min5Two Meters, One High-Resistance Node: A Lesson in Loading Error
A student must verify the bias of a sensor front end: a 470 kΩ resistor from a 10.00 V regulated rail to a node, and a 470 kΩ resistor from that node to ground, so the expected node voltage is 5.00 V. The only meter available is an analog multimeter marked 20 kΩ/V DC sensitivity.
900 words, about 5 min