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Simple UPS

This is the circuit diagram of a simple UPS that can deliver 12V unregulated and 5V regulated DC. The transformer T1 steps down the mains voltage to 12V AC and then the bridge B1 rectifies it. The rectified signal is smoothed by the capacitor C1

Transistor codes

There are three main series of transistor codes used in the UK:The first letter B is for silicon, A is for germanium (rarely used now). The second letter indicates the type; for example C means low power audio frequency; D means high power audio frequency; F means low power high frequency.

Resistance Conductance & Ohm's Law

Resistance Conductance and Ohm's Law. It is the property of a material due to which it opposes the flow of electric current. "R" represents it. It, s unit is called ohm.



Opposition to the flow of current is called resistance and the device or component used for this purpose is called resistor.


A transformer is an electrical device used to change the  value of an alternating voltage. transformers are widely used in electrical  work.


Any linear bilateral circuit, which contain, G/R of same frequency the current that flows in any branch is the sum of the current's that would result from each G/R Working independently while other G/R.


Ohm's law states that in an electric circuit the current is directly proportional to the applied voltage and inversely proportional to the resistance of the circuit.

Magnetism Rules

This rule is used for the determining the direction of magnetic field. If we rotate screw in the cork by a screwdriver.


thevenin theorem is a procedure by which we change a complex network in to simple network called thevenin's equivalent circuit.

Insulation Resistance Test on a Transformer

Transformer Insulation Resistance Test Insulation resistance test on a class 1 and class 2 transformers.

Faraday's law's of Electromagnetic induction

First Law of Faraday's Electromagnetic Induction state that whenever a conductor are placed in a varying magnetic field emf are induced which is called induced emf, if the conductor circuit are closed current are also induced which is called induced current.

Inverter Project 12v DC to 120V AC

Inverter is a device that converts 12 volts dc to 120 volts ac, which is what we use in our homes.  This project will handle about 300 watts, which is perfect for lights, small T.V.'s and radio equipment.


In Figure we can now look at the circuit from the example, redrawn with the calculated voltage and current values included.

UPS - Uninterrupted Power Supply

Some time disturbance of power supply creates a number of problems.  Especially in sensitive departments such as Radar System, Hospitals, Telephone exchanges and industries etc.


Resistance Test on a Transformer Connect an ohmmeter across the two ends of the primary winding of the transformer and record the resistance.


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