ROHS Compliance

The RoHS is the Restriction on the use of Hazardous Substances in Electrical and Electronic Equipment.  

This is an official directive by the European Union.   The RoHS bans any electrial or electronic equipment which contains more than the stipulated levels of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and PBDE (Polybrominated diphenyl ether) flame retardants. 

related resources

http://www.rohsguide.com

Transient Voltage Supression Diode

A Transient voltage suppression diode  is a diode which is used to protect a circuit against spikes and transient overvoltages.

Spikes can be caused due to switching, lightning strikes and faults in the circuit.  A spike lasts for a small period of time of the order of microseconds.  However, the energy dissipated in a spike is such that it can damage components in a circuit.  

Hence,it is necessary to protect spikes from reaching the components by shunting through a transient voltage suppression diode.  A transient voltage suppression diode is connected in the reverse bias.  With the anode to the negative and the cathode to the positive.

During normal supply voltage, the transient voltage suppression diode is in the non-conducting state.  

When the voltage rises and exceeds the breakdown voltage of the diode, it starts conducting and the surge is diverted before reaching the component.  TVS Diodes can be connected with the anodes facing each other to provide bidirectional protection

When the surge subsides and the voltage returns to normal, the Transient voltage suppression diode comes back to its non-conducting state.

The Transient Voltage Suppression diode has a VI characteristic which is similar to the zener diode.  However, the zener is designed to regulate the voltage while the Transient voltage suppression diode is used to protect against overvoltage.

Gallium Arsenide - Semiconductor, An Overview

Gallium is a compound which is used as a semiconductor.  It is a combination of the elements gallium and arsenic.  Gallium is an extremely rare element.

Gallium Arsenide is used widely in the manufacturer of diodes, Field Effect Transistors and in the manufacture

Gallium Arsenide is used for fast switching applications and for components functioning at ultra high radio frequencies.

Gallium Arsenide is used in optical communication system and is used in LEDs.

Panasonic Launches new Pin Sized Battery

Panasonic has launched a new pin sized battery aimed at the wearable gadget market. Wearable gadgets such as smart watches need more and more power from smaller and smaller sized batteries.

The pin sized battery is 20 mm long with a diameter of 3.5mm. It is about 20 times smaller than an AAA battery. The battery weighs just 0.6 grams and has a voltage of 3.75 volts. It has a capacity of 13 mAh. The battery which is rechargeable is called the CG-320.

Panasonic says that mass production and shipping will begin by February 2015 with an initial output of a hundred thousand units.

 Check out
http://panasonic.co.jp/corp/news/official.data/data.dir/2014/10/en141003-2/en141003-2.html

What is a Captive Power Plant ?

A captive power plant is a power plant owned by an factory for its own power consumption.  That is, all the power generated in the captive power plant is consumed by the factory itself.

Many industries such as textile units, cement factory and petrochemical industries require cheap and reliable power.  The utility may not always meet their needs.  Hence, they set up their own power plants.  These plants do not supply power to the grid.  

These plants are mostly less than 50 MW.

The Alternator in a Car

The Alternator in a car generates power for all the electrical equipment in the car.  The Alternator is driven 

by the engine by means of a belt known as the serpentine belt.  The belt drives the shaft of the alternator.  

The rotor of the Alternator contains the field windings.  The field windings are excited by a Voltage regulator. 

The exciting supply to the field windings is through slip rings.  This supply is taken from the batteries.  The 

power is generated on the stator of the alternator which makes evacuation easier.  

The output of the Alternator is AC.  This AC supply is converted into DC by means of diodes.  The DC supply is used to charge the battery and to supply power to all the electrical fitments in the car. 

What is an Anti Fuse ? Where is it used

An Anti fuse is a device which fuses when there is a high voltage across it.  Just as a fuse opens the circuit in the case of an abnormality, the antifuse closes the circuit in the event of an abnormality.

An example of an antifuse can be a serial light connected to the domestic supply voltage.  The individual bulbs are not rated for the domestic voltage.  However, as they are connected in series, they are able to withstand and function in the domestic supply voltage.

A series of 48 lamps of a rating of 2.5 volts can withstand 120 volts.  A series of 96 lamps can withstand 240 volts.

When one lamp in the series fails, there is a risk of the other lamps not getting the supply as the circuit is open circuited.

This is avoided by having an antifuse below the filament which fuses when the bulb filament fails.  This happens as the system voltage is applied across the single bulb.

Once the antifuse operates and closes the open circuit, the current flows as usual to the remaining lamps.

In Electronics, antifuses function by modifies the circuit in microchips depending on the logic to be programmed.  An antifuse is typically an insulating layer sandwiched between two conducting layers.  When the chip is to be programmed, a voltage is impressed across the layer which fuses.