ISRO Skill Test & Document Verification 🔥 | My Personal Experience + Actual Questions Asked

Summary

The presenter recounts his experience taking an electronics skill test and completing document verification at Vikram Sarabhai Space Centre (VSSC) in Thiruvananthapuram. He describes the day’s process, the practical test setup, and the two questions he says he was asked. His account is based on his own experience, so procedures and questions may differ for other candidates or posts.

Arrival and document verification

• The presenter travelled to Thiruvananthapuram the day before the test and stayed near the venue.
• On arrival, candidates went through security screening. They were asked to switch off their phones and leave them aside before entering.
• Candidates waited together in a large hall. The presenter says tea and snacks were provided.
• Recruitment staff checked candidates’ documents one by one. These included educational certificates—such as 10th, 12th, and diploma certificates, depending on the candidate’s qualifications—and applicable caste-category certificates.
• Staff also asked routine identity questions, such as the candidate’s name, date of birth, and father’s name.
• The presenter describes the staff as supportive, while stressing that candidates should bring all required documents. He says category certificates matter because the qualifying marks he recalls were 50/100 for General candidates and 40/100 for OBC/SC/ST candidates.
• Candidates received lunch coupons. After lunch, groups were taken by bus from the administrative area to the building where the practical test was held.
• He also recalls hearing a rocket launch while in the area, which he found exciting.

Skill test format

• In his electronics test, the presenter says there were two questions worth 50 marks each: one on analog electronics and one on digital electronics.
• The test lasted about three hours.
• He recommends getting practical experience with lab equipment before test day. He practised at a friend’s college after asking a staff member for access to the equipment.

Question 1: Analog electronics

The first task involved assembling a transistor circuit and examining its output.

• Candidates were given a circuit diagram and components, including resistors, capacitors, and transistors.
• They had to identify component values, using a multimeter where necessary. A diagram showed the transistor’s emitter, base, and collector.
• Candidates had to build the circuit on a breadboard.
• The specified input was a 10 V peak-to-peak, 1 kHz sine wave, supplied by a function generator.
• The input and output were connected to a CRO/oscilloscope so both waveforms could be viewed. The presenter says the circuit’s output was a square wave. Candidates had to:
  • identify or name the circuit;
  • show the output waveform; and
  • calculate its duty cycle from the waveform’s timing.
• The presenter initially saw noise on the output. He and the invigilators suspected a grounding or probe-placement issue; after adjusting the setup, the waveform appeared correctly.
• He could not identify the circuit by its expected name and wrote “sine wave to square wave converter” instead. He believes this cost him marks. He reports scoring 90/100 overall, though his explanation of the exact mark deduction is his own estimate.

Question 2: Digital electronics

The second task was to build and verify a 4-to-1 multiplexer using a digital trainer kit.

• The presenter says no finished circuit diagram was supplied, so candidates had to work out the logic themselves.
• A 4-to-1 multiplexer selects one of four data inputs according to two select lines:

Select lines Selected input 00 I0 01 I1 10 I2 11 I3

• He describes implementing the logic with NOT and AND gates, wiring the inputs and select lines, and connecting the output to an LED.
• Candidates then changed the input and select-line states to check that the correct input appeared at the output and to verify the truth table.

Practical tip: Check patch wires and probes for continuity with a multimeter before using them. A faulty lead can make troubleshooting difficult, especially in a circuit with many connections.

Main preparation lessons

• Practise breadboarding and using a function generator, CRO/oscilloscope, digital trainer kit, and multimeter.
• Review both the theory and practical implementation of analog and digital circuits.
• Be prepared to identify circuits, trace transistor pins, interpret waveforms, calculate duty cycle, and verify a multiplexer’s truth table.
• Bring the required original documents and check them before travelling.
• If you lack access to equipment, ask a college or lab staff member whether you can practise. The presenter’s advice is to seek help rather than assume access is impossible.

Speakers and sources featured

• The video presenter: Shares his VSSC document-verification and electronics skill-test experience, explains the questions, and offers preparation advice.
• Recruitment staff and test invigilators: Referred to by the presenter as checking documents and assisting with the test setup; they are not presented as separate speaking sources in the subtitles.