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. 

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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 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 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.

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