Avalanche Breakdown is a type of breakdown usually seen in PN junctions which are connected in reverse bias.  When the reverse bias voltage exceeds the peak inverse voltage of the PN junction, the junction will break.

When a PN junction is connected in reverse bias i.e. the P material to the cathode and the N material to the anode, the size of the depletion region becomes maximum and the current becomes very low.  The electron-hole pairs which cross over to the depletion layer are drawn to opposite sides.  The acceleration of these charge carriers depends on the electric potential.  

At high potentials, the electron can collide against atoms and consequently cause other electrons to get knocked out.  These electrons in turn will collide with other atoms and knock out more electrons.  The process continues until more and more electrons are knocked out.  This ultimately leads to the failure of the PN junction.

This is a common mechanism of failure of diodes connected in reverse bias.  Hence, the Peak inverse voltage of diodes should be checked against the maximum voltage they would have to withstand.  


EEPROM stands for Electrically Erasable Programmable Read Only Memory.  It is also called E2PROM.  EEPROM is a type of Read Only Memory.  The data in an EEPROM can be erased by applying an electric charge to it.  

The data in an EEPROM needs to be erased one byte at a time.  In contrast, in Flash Memory, the data is erased and written in blocks which makes it faster.

The Spark Plug is the device which generates the spark for combustion of fuel in an internal combustion engine.  The spark is generated by the high voltage which is supplied to the spark plug by the ignition coil.

The Spark Plug contains a central electrode which is enclosed in a porcelain body.  The metal shell of the spark plug is connected to the engine block or the cylinder head and is thus electrically grounded.

The spark gap is the location where the spark appears.  The gap is formed by the central electrode and the electrode from the grounded body.  The gap between the two electrodes is very small.

When the high voltage from the Automobile ignition coils is applied to the the central electrode, the high voltage causes an arc to form across the two electrodes.  

This spark ignites the fuel/air mixture in the engine.  

The spark gap experiences very high temperature during the spark.  Hence, special materials and fabrication techniques are adopted in its manufacture.  


The Flash EEPROM or Flash Memory as it is popularly known is a type of Electrically Erasable Programmable Read Only Memory.  It is different from conventional EEPROMs in that the memory can be erased quickly, in a "flash".  Hence its name.  Flash EEPROMs are widely used in computers, in electronic devices such as cameras, cellphones and camcorders.

Flash EEPROMs are continually being made in smaller sizes.  Pen Drives are an example of Flash EEPROMs

The Heat Soak Test is a test conducted for Electronic Components to see if they are able to perform at elevated temperatures.  The theory behind the test is that  chemical reactions can be accelerated at high temperature.  The failure of electronic components such as transistors, diodes, capacitors, etc occur when the chemical properties of the materials change at high temperature.

The Heat Soak Test helps ensure that the components are chemically stable at high temperature and that they have been sized properly.  

The soak test gives and idea of the components stability over a prolonged period of time.

The soak time can vary from a few hours to a few weeks.  

Electronic Components are very sensitive to heat.  Hence, arrangements should be made to evacuate the heat generated internally due to the passage of components in the components.

Heat also causes the chemical properties of the components to change.  This can lead to premature failure due to change in the operating characteristics.

Hence, special provision have to be made to remove the heat generated as quickly as possible.  This prevents the temperature from rising.

Some electronic equipments may have to be placed in an air conditioned environment.

Peak Inverse Voltage refers to the maximum reverse bias voltage a PN junction can withstand.  It is  also known as Peak Reverse Voltage.

Diodes will have the Peak Inverse Voltage mentioned on them.

The Peak Inverse Voltage should be greater than the maximum reverse voltage the diode will be exposed to.


Electronic Devices such as ICs, transistors are painted black as a black surface dissipates heat more effectively.

In Thermodynamics, it is called black body radiation.

Peltier Cooling Plates work on the principle of the Peltier Effect.  The Peltier Effect states that when a voltage is applied across a thermoelectric junction heat is generated on one side and cooling occurs on the other side.  

The device has two sides.  Heat is brought from one side to the other.  If the heat from the hot side is removed by means of a heat sink, the temperature of the cool side will fall significantly.

When the plates are used in cascade, the temperature can be lowered to very low values.  

Peltier Plates are use to cool components such as ICs, power transistors, etc.   Peltier Cooling Plates are also used for portable refrigerators which can be used in cars and in camping.  

Peltier Plates are compact and can be designed in very small sizes.  The downside is their low efficiency.

Ignition Coils are used in automobile systems to generate the high voltages required for the spark in the spark plug.  The ignition coil consists of two windings.  The primary winding which is connected to the battery and the secondary winding which is connected to the spark plug.  

The primary winding is made of thick copper wire of small number of turns while the secondary winding has a higher number of turns and is made of thin wires.  The core is made of laminated magnetic material.

Power from the battery flows through a switching circuit to the primary winding which has smaller number of turns.  When the spark is to be generated a cam operates the switch in the primary circuit.  The current to the ignition coil is interrupted.  This causes the magnetic field in the coil to collapse and a high voltage is built up in the secondary winding.  This winding is connected to the spark plug and causes the spark across the spark gap.

The voltage generated in the secondary winding can be of the order of thousands of volts.