Maharashtra HSC Electronics Field Technician (NSQF F6) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Ohm's Law

Current through a conductor is directly proportional to voltage across it and inversely proportional to resistance, expressed as V = I × R, valid for linear resistive elements at constant temperature.

Power in a Resistor

Power dissipated equals voltage times current, or I squared times R, or V squared divided by R. A resistor must be rated above the calculated dissipation to avoid overheating.

Resistor Colour Code

Bands give digit, digit, multiplier and tolerance. Brown-black-red-gold reads 1, 0, times 100, plus or minus 5 percent, giving 1 kilo-ohm with 5 percent tolerance.

Zener Diode Regulation

A Zener diode is operated reverse-biased in its breakdown region, where voltage stays nearly constant despite current change, so it regulates supply voltage across a load.

Series Resonance

In an LC series circuit, inductive and capacitive reactances cancel at f-zero equal to one over two pi root LC, leaving only resistance and maximum current.

PMMC Meter

A permanent-magnet moving-coil instrument deflects in proportion to average current and works only on DC; a rectifier is added to allow AC measurement.

Voltmeter Loading Effect

A voltmeter's finite resistance draws current from the circuit and lowers the measured voltage. Sensitivity in ohms per volt indicates how much the reading is affected.

CRO Time Measurement

Signal period equals the number of horizontal divisions occupied by one cycle multiplied by the time-per-division setting; frequency is the reciprocal of that period.

Clamp Meter Use

A clamp meter senses current from the magnetic field around a conductor. The jaw must close around a single wire, otherwise opposing fields cancel and read zero.

Bridge Rectifier Output

A full-wave bridge uses four diodes so both half cycles conduct, giving ripple at twice supply frequency and peak output near input peak minus two diode drops.

Op-Amp Inverting Gain

For an inverting amplifier the voltage gain equals negative feedback resistance divided by input resistance, and the output is 180 degrees out of phase with input.

Universal Logic Gates

NAND and NOR gates are called universal because any other logic function, including NOT, AND and OR, can be built using only NAND or only NOR gates.

JK Flip-Flop

The JK flip-flop removes the invalid state of the SR flip-flop: when both J and K are high, the output toggles on each clock pulse instead of being undefined.

555 Astable Mode

In astable mode the 555 timer produces a continuous rectangular wave; frequency is approximately 1.44 divided by the product of total timing resistance and capacitance.

SMPS Working

A switched-mode power supply rectifies mains to high-voltage DC, switches it at high frequency through a transformer, then rectifies and filters the low-voltage output.

Microwave HV Capacitor

The high-voltage capacitor in a microwave oven stores a lethal charge after the mains is removed, so it must be safely discharged before any servicing begins.

Ceiling Fan Capacitor Fault

A ceiling fan that hums but runs slowly or not at all often has a failed run capacitor; checking its microfarad value and the winding continuity confirms the fault.

Induction Cooktop Load

An induction cooktop heats only ferromagnetic cookware by inducing eddy currents; aluminium, copper and glass vessels do not heat because they lack suitable magnetic properties.

AM Modulation Index

The modulation index of an amplitude-modulated wave is modulating voltage divided by carrier voltage; values above one cause overmodulation and distorted, splattered reception.

Superheterodyne Principle

The receiver mixes incoming radio frequency with a local oscillator to produce a fixed intermediate frequency, which is amplified and filtered for good selectivity and stable gain.

Dipole Antenna Length

A half-wave dipole length in metres is roughly 143 divided by frequency in megahertz; a quarter-wave monopole is about half that value.

Amplifier Speaker Matching

Speaker impedance should match the amplifier's rated load. A much lower impedance draws excessive current and can damage the output stage through overheating.

8051 Machine Cycle

On the classic 8051, most instructions take one machine cycle of twelve clock periods; with a 12 MHz crystal each machine cycle lasts one microsecond.

Arduino ADC Resolution

The ATmega328P has a 10-bit analog-to-digital converter, mapping input voltage from zero to five volts onto integer values from zero to 1023.

Ultrasonic Distance Formula

Distance equals echo time multiplied by the speed of sound, divided by two, because the pulse travels to the object and back to the sensor.

Flyback Diode Purpose

A diode across a relay coil gives the collapsing magnetic field a path to discharge, protecting the switching transistor from a damaging voltage spike.

PWM Duty Cycle

Pulse-width modulation switches a supply on and off rapidly; duty cycle is on-time divided by total period, and average output voltage scales with it.

ELCB or RCCB Function

A residual-current device compares live and neutral current and trips when a small difference, typically 30 milliamperes, indicates leakage to earth.

Lockout Tagout

Before servicing, isolate the supply, prove the circuit dead with a tester, discharge stored energy, then lock and tag the isolator to prevent re-energisation.

Earth Wire Colour

In Indian wiring the protective earth conductor is green or green with yellow stripes; it must never be used as a live or neutral current-carrying conductor.

Vernier Calliper Least Count

Least count equals one main-scale division minus one vernier-scale division; on a standard calliper with 50 vernier divisions it is 0.02 millimetres.

GST Registration Threshold

In most Indian states GST registration becomes mandatory when annual turnover exceeds 40 lakh rupees for goods or 20 lakh rupees for services.