Basic Electronics

APPLICATIONS OF ELECTRONICS

Beauty of Electronics - Sophistication in miniaturization - If you know it then you are a doctor and if you don’t then you are a patient - Datasheets are boons for dealing with any component or IC, you are unaware of - Most versatile in technological applications- a single IC can sometimes perform hundreds of different operations - A driving force of few watts controls the activities of the giants - Machinery, automobiles, all household appliances, whole communication system, automization, defense, weaponry and many more damn things….

BASIC DEVELOPMENT TOOLS Breadboard

Multimeter PCB, ECB

Resistances

a) Fixed - carbon - wire wound

b) Variable - Rheostat, Pot, Preset App. – tuning, voltage curves, voltage dividers --Photoresistors (LDRs), thermistors App. – sensors, safety devices, volume

Capacitors - polarised (electrolytic, tantalum)

- unpolarised (small value)

App.- storing elec. energy, filters, timing circuits -- Variable (very small value) App.- radio tuning ckts -- Trimmers (like presets)

Diodes ( conduct in one dir)

Switching- (p-n junc) App.- switch, rectification

Schottky- (M-SC contact) App.- high speed switching, RF, low loss rectifier Zener- (rev breakdown) App.- vol reg, safety ckts

Photo (rev current increases linearly) App.- solar cells, photometry, auto lighting, camera Laser- in optical devices and disco lights LEDs- (emits light in FB) App.- opto-isolator with photo diodes, sensors, lighting, power status, flash

Tunnel, point contact, step recovery, varicap, pin, crystal, avalanche, gunn, peltier, clamping, welding….

Transistors- (building blocks of circuitry) App.- amplification, switching, all ICs and productive ckts, super beta, high vol, audio…. -- BJT, FET (JFET, MOSFET), unijunc, avalanche, photo, darlington, alloy junc….

BJT- (majority/minority carriers, E-B-C, two p-n junc, current operated, NPN-PNP)

VHF-UHF (2N3866/4427) Si-NPN, TO-39, low power Small Signal (BC-327/328, BC-556/57/58/59/60) Si-PNP, TO-92, switching, amplification

General purpose (BC-546/7/8) Si-NPN,TO-92, amplifier, 625 mW SL/CL-100 (TO-39)

- FET- (unipolar, n/p-channel, S-G-D) a) JFETS

b) MOSFETS

App.- precision, comp logic, Digi ICs, MUXing Phototransistors- photodetector, camera, cd players, VCRs, TV

- Darlington/array- huge amplification, buffering, motor drivers, touch sensitive switch

- Some ckt app.

cascading

Biasing

multivibrator

tuned amp

power amp

TRANSFORMERS generally for step-down from AC-mains to 18/12/9/6 V etc. - current rating is important

LINEAR ICs - Amplifiers- for increasing voltage or power (audio, video, radio freq, wide band, differential)

Op-Amps (high gain voltage amp) - LM-741 (mono op-amp, 8 pin)

- LM-158/258/358/2904 (low power dual op-amp, 8 pin)

- LM-124/224/324 (low power quad op-amp, 14 pin)

- Applications- diff. amp, oscillator, voltage follower, inverter, adder, subtractor, AC vol amp, rectifiers, peak detector, clipper, clamper, S/H, comparator, multiplier/divider, differentiator/integrator, zero crossing detector, phase detector, schmitt trigger, square/triangular/sine wave generator…

555 Timer (TO-99 can or 8 pin mini DIP) - Generates accurate time delay and oscillation a) astable b) monostable c) bistable App.- power on delay in appliances, oscillator, pulse/ramp/square wave generator, traffic light control, burglar alarm, timed-bombs, missing pulse detector, frequency divider, PWM, FSK generator, PPM, schmitt trigger, lifts…..

Voltage Regulator zener, op-amp, SCR, 78XX, 723, 317, switching 78XX/79XX (TO-3 metal, TO-220 plastic) XX=05,06,08,12,15,18,24 -2 and -5.2 too in 79XX App.- fixed series regulation, adjustable reg,double voltage supply, IC supplies, precision meters

723 (14 pin DIP, 10 pin metal can) App.- general purpose, low/high voltage reg, appliances

Switching- (2653, 2727, 64 42)-by PWM (duty cycle) high power eff, even higher voltage than i/p, opp polarity too App.- portable comps

ADC- converts analog signal to several line/bit digital value - ADC 0803/04- (CMOS 8 bit, 20 pin,5v, 100 microsec., microP compatible, 0-5 v range)

- AD 7824/28- (4/8 analog channel, Linear Compatible CMOS high speed, 8 bit,24/28 pin 5v, 2.5 microsec/channel) - App.- microprocessor interface, interfacing linear ckts, digital meters/displays, sensor ckts……

Common ckts

DAC- converts several line digital value to analog equivalent AD7524- (8 bit, 100 ns settling time, 80 ns prop delay) 0830/1/2- (CMOS, 8 bit, double buffered, 1 microsec sett time)

App.- audio players, sound cards, video, computer interface

SENSORS LIGHT- LED, laser, LDR, photo transistors/diodes LDR- resistance varies with intensity of light hence gives variable output voltage in the ckt which is tracked for sensing purposes- led, lasers are light sources

App.- burglar alarms, robotics, light operated clocks, shadow detector, automatic lighting, dimmer, LCDs, mobiles

IR- IR led, TSOP 17XX, PIR, pyroelectric - TSOP 1730/36/38/56- (receiver- photodetector+preamplifier, -0.3-6 v, 1200 bits/sec data transmission)

- Passive IR (PIR)- measure IR light radiated from objects in field of view - Pyroelectric- (IRA-E700/900/940)- highly sensitive

- App.- motion detector, burglar alarms, remote thermometer, night vision, IR camera, surveillance/monitoring, diagnostics

Temperature- thermistor, AD590, LM335 - AD590- constant current source dependent on temperature - LM135/235/335- precision sensors, 2 terminal zener, brekdown voltage proportional to temp, -40 to 150 deg C

- App.- appliances, overheat protection, fire alarms,

Pressure- diaphragm, liquid level, gauge

- pressure transduced into electrical quantity - variable capacitance- one plate is diaphragm of sensor - piezoresistive- piezoresistive strain induces voltage

- App.- pressure sensing, altitude sensing, density, weighing machines, impact sensing, security, lifts

Switches - Binary devices which interrupt the flow of electrons in a ckt by any physical or chemical process - Limit- (machine motion operated switch)- lever actuator, proximity (energised by moving magnet), optical

- Process- pressure (gas/liquid-piston/diaphragm), speed (rotory speed of shaft), temperature (bimetallic, brass bulb) , liquid level, liquid flow, tilt (mercury), reed (magnetic field)

Hand- rocker, toggle, pushbutton, slide, joystic, tact, DIP, snap action, rotary, key lock, navigation, leaf

- Pole- no. of contacts/levers - Throw- no. of contact positions/ways/switching positions

break before make make before break

Applications- ckts, robotics, machines, alarms, all industries/ appliances, automatic/property controlled switching, robotic toys, multiple/secure/compact/easy switching, changers…..

Relays- solenoid is used to actuate a set of switch contacts - controls a large amount of current and/or voltage with small electrical signal - acts as binary amp (controls one electrical signal with other) - coil and contact ckts are electrically isolated - pull in current- min current for actuation - drop out current- max current at which contacts come in normal state

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Latching (bistable states) Contactor (electric motors starter) Reed (contact in gas tube- no corrosion) Mercury wetted (no bounce), Solid state (no movables – SCR, opto triac - optically coupled) Overload protection (bimetallic) Time delay (shock absorber attached to armature by pneumatic dashpots/fluid filled piston/RC ckts)

- App.- automatic switches/changers, telephone exchange, industries, protection, electronic ckts, interfacing, decoupled ckts interaction….

DIGITAL ICS - Bit (binary digit)- two discrete values for more reliability (0-1) - Codes- BCD(8421), 84-2-1, 2421, excess 3, biquinary (5043210) - Binary logic follows boolean algebra and represented by truth tables - Three basic operations- AND, OR, NOT - Digital IC typesSSI- few gates, basic logic operations MSI- 10-100 gates, performs complete logic function LSI- more than 100 gates VLSI- thousands of gates

Gates

Decoders/demultiplexers – combinational ckt which converts n bit binary information to one of 2^n unique outputs - demux is a decoder with an enable input - 3-8 line- 7411238, 74138 - 4-16 line- 74154, 744514, 74159 - dual 2-4 line- 74139 - bcd-decimal- 7442 ……………..

Encoder – MUX/Data Selectors- reverse of decoder 2^n – n line, IC packages- priority encoder - Multiplexing- transmitting large no. of information units over smaller no. of lines - 74147 - 10 line decimal to 4 line bcd - 74148, 4532 B - 8 data lines to 3 lines binary - 74157 - quad 2 line to 1 line MUX

- App.- code conversion, interfacing, selecting lines from a ckt, electronic locks, ROM (decoder + programmed Ors ), buses,

BCD – 7 Segment display driver/decoder CD 4511 and 7447

Computer design - Digital Computer is a discrete information processing system - discrete elements of information are represented by signals - two (binary) discrete values- 0/1 Gates < adders/decoders/MUX/ROM/PLA/binary cells (flip flops/ferrite cores/punched cards) < registers/counters < memory/ALU/CU/processors < CPU < digital/microcomputer

Sequential logicMemory ALU Micro-processors Micro-controllers/PIC

Latke-jhatke Darlingtons Thyristors (SCR), diac, triac Varicaps Digital thermometer