Maharashtra HSC Electronics (Bifocal) case studies
Maharashtra HSC Electronics (Bifocal) · Put your knowledge to work in context.
The Maharashtra HSC Electronics (Bifocal) is a state-board subject taken alongside the standard Class XII science or arts programme, giving students a vocational electronics qualification recognised for further study and entry-level technical work. It suits candidates who want hands-on circuit skills rather than an entirely theory-heavy subject set, and who intend to move into diploma or degree programmes in electronics, instrumentation, or IT, or into technician roles. The Maharashtra HSC Electronics (Bifocal) case studies are 5 cases and about 4,338 words.
1Shunt Zener Regulator That Only Overheats When the Load Is Disconnected
A final-year project powers a sensor board from a 12-0-12 V, 500 mA transformer through a bridge rectifier, a 470 uF reservoir capacitor, a 220 ohm series resistor and a BZX55C5V1 zener (5.1 V, 500 mW). The board draws between 0 and 45 mA.
841 words, about 4 min2Relay Driver That Buzzes and Then Destroys Its Transistor
A student builds a relay driver for a 12 V relay whose coil measures 250 ohm (48 mA) using a BC547 (hFE minimum 100 at 48 mA, VCEO 45 V, Ptot 500 mW) driven from a 3.3 V microcontroller GPIO through a 10 kohm base resistor. No freewheel diode is fitted anywhere in the circuit.
811 words, about 4 min3Counter That Jumps Counts When a Hand Approaches
A breadboard counter takes pulses from a slotted opto-sensor whose output is an open-collector phototransistor with a 10 kohm pull-up, carried over 5 m of unshielded cable to a 74HC14 Schmitt inverter. The counter and 7-segment driver are 74LS devices, and a 5 V bench supply feeds the board through 20 cm leads.
893 words, about 4 min47805 Supply That Drops Out and Shuts Down After Two Minutes
A 230 V/50 Hz to 9 V, 1 A transformer feeds a bridge rectifier (four 1N4007), a 1000 uF/25 V reservoir capacitor and a 7805 in TO-220 with no heatsink. The load is a logic board plus a relay drawing 0.60 A continuously.
830 words, about 4 min5ADC Readings, a Bouncing Button and a Relay on a Microcontroller Pin
An ATmega328P board runs at 5.0 V nominal from a USB adapter that actually delivers 4.78 V, and AREF is left at the default AVcc. Firmware sets the ADC prescaler to divide by 128 with a 16 MHz clock and reads a 100 kohm/100 kohm resistor divider on ADC0 with a single conversion.
963 words, about 5 min