RRB JE CBT 2 - Electronics case studies
RRB JE CBT 2 - Electronics · Put your knowledge to work in context.
RRB JE CBT 2 Electronics is the second-stage computer-based paper for candidates who have cleared CBT 1 and are competing for Junior Engineer posts in Indian Railways where the technical trade is Electronics. It is meant for diploma and degree holders in electronics, electronics and telecommunication, or allied branches who want a workshop, signalling, telecom, or maintenance engineering role in the railway system. The RRB JE CBT 2 - Electronics case studies are 5 cases and about 3,236 words.
1Zener Shunt Regulator That Drops Out at Full Load
A 12 V unregulated supply with ±10 % variation (10.8 V to 13.2 V) feeds a 6.2 V shunt regulator. The series resistor is 220 Ω and the Zener is a 1N4735A (Vz = 6.2 V at Izt = 41 mA, Zz = 10 Ω, Izk = 1 mA, 1 W at 25 °C with 8 mW/°C derating above 25 °C).
664 words, about 3 min2Ripple Counter Feeding a Decoder and Comparator
A student prototype of a batch counter uses a 74LS93 4-bit ripple counter clocked at 1 MHz. Outputs QA–QD drive a 74LS47 BCD-to-seven-segment decoder for a common-anode display, and also a 74LS85 comparator set to detect decimal 12, whose output fires a retriggerable 1 ms monostable that holds a relay on through an NPN transistor.
681 words, about 3 min3AM Transmitter Modulation Headroom and Receiver Image
A community AM broadcast transmitter runs a 2 kW carrier at 1400 kHz with 7 kHz audio bandwidth into a 50 Ω antenna. The PA is rated 3 kW average and 6 kW peak envelope power.
645 words, about 3 min424 V Pump Feeder Voltage Drop and Cable Sizing
A 24 V battery bank with an internal resistance of 0.05 Ω feeds a 240 W pump controller through a 30 m run of two-core cable. Each conductor has a resistance of 0.012 Ω per metre.
615 words, about 3 min5Voltmeter Loading and Ammeter Shunt on the Calibration Bench
A calibration bench is checking a 20 V DC supply that feeds a precision divider made of two 100 kΩ, 0.1 % resistors in series; the tap should be 10.00 V. Technician A uses an analog multimeter on its 10 V range, sensitivity 20 kΩ/V, and reads 8.0 V.
631 words, about 3 min