S.A electronics

The opposition offered by a substance to the flow of electric current through them is called resistance All materials oppose the flow of electric current through them i,e they have resistance Since the current is the flow of free electrons, resistance is the opposition offered by the substance to the flow of free electrons.this opposition occures because atoms and molecules of the substance obstruct the flow of these electrons .certain substances  offer very little opposition to the flow of electric current are called conductors e,g copper ,aluminium ,silver etc On the otherhand substances which offers high opposition to the flow of electric current  are called insulators e,g glass, rubver mica etc The resistance is the friction offered by the substance and causes production of heat with the flow of current.the moving electrons collide with the atoms or molecules of the substance, each collision resulting in the liberationof minute quantity of heat The unit of resistance...

When  we place two conducting surfaces  close to each other and separated by a dielectric or any insulating material between them then a capacitor /condenser is formed                   OR Any two conducting surfaces separated by a dielectric is called condensor or capacitor Aluminium and tin are the most common conducting materials used in capacitor Paper ,oil, ceramic,polyster etc are common insulataros The two conductOr plates are usually kept parallel and the dielectric material keeps the conductor plates separated from each other The capacitor functions as to store electrical charge and then releases it as when this energy is required                 WORKING lets consider a capacitor And connect it with a battery through key K When we press the key the current flow through the circuit The electrons from plate A will be attracted by the positive terminal of battery and these el...

A transistor or thermionic valve based circuit capable of increasing the amplitude or power of an input signal is called amplifier actually speaking the amplification capacity of the transistor or valve is the base of amplifier the reception capacity of the earliest type of receivet was limted up to 40-80 KMS only triode was not invented at that time public address amplifiers and wide range reception capacity type radio receivers could only be made after  the invention of triode valve after knowing its amplification capability A multi stage a,f amplifier (a.f. range_2hz to20 kHz) is used in public address amplifier which amplifies the a.f output of a microphone upto such a level  that a number of powerful loudspeakers can be operated simultaneously .in this way ,the voice  of a person can be made  to reach thousands of listeners present in a large Stadium or in a field In radio receiver .the microvoltage level r,f output of an aerial is converted into several vol...

This circuit allows automatically on and off the street light during day and night How it works The working principle is very simple  during day hours the ldr offers little resistance due to this the voltage flows from +12 to the base of transistor through R3and mixes with negative voltage which is already present there due to this it becomes zero volt no current flows through transistor it flows only when there is negative voltage present on base of transistor as it is a PNP transistor and conducts only when ever negative voltage is present on the base pin During night the ldr offeres high resistance so no voltage flows through ldr to base pin and the negative voltage is present there in this way the transistor conducts and current flows through the emitter to collector and energized the relay

This is very simple circuit on MOSFET Irf3205  Working; The drain pin & source pin is controlled by gate pin these pins works according to gate pin of MOSFET if there is no slightly voltage on gate pin no voltage flows from drain to source it depends upon gate pin If we increase voltage on gate pin the voltage flow from drain to source also increase or vise versa Features; It can take load upto 150watts And can change voltage from{0-50Volt) Components required; Capacitors C1=3500uf/50v C2=0.1uf C3=100uf/50v Resistors; R1=10k V.R=10k{variable} Bridge=6amps Transformer Stepdown(0-50v) Mosfet Irf3205 Output voltage=0-50v

Circuit diagram

This is very simple inverter circuit based on ic ne 555 The ic works as frequency generator It produces a frequency of 50-60Hz Then this frequency is fed to FETs  which works according to given signals from 555 These FETs works as switches which generates 50-60HZ frequency in the transformer coil in this way accurate Ac 220v with 50-60Hz becomes output We can also use any high power  FETs /MOSFETs with heat sink to protect FETs/Mosfets Components Capacitors 0.1 uf =2no 1000uf 25v =1no Ic=ne555 Transistor=Bc549 =1no Resestors 4.7k=1no 120k=1no 1k= 3no Fets Irf540

Cev=60v Cbv=100v Ebv=7v Collector current=15A Collector power=115w Hfe20-70 Frequency=3mhz

Collector emitter voltage=30V Collector base voltage=30v Emitter base voltage=5V Collector power=500mw Hfe=110-800 Frequency=150Mhz Type=pnp