Electrical And Electronics Engineering: March 2016

Thursday, 31 March 2016

Layout Circuit Of 100 Watt Square Wave U.P.S

Components Required
1- Transformer 12 - 0 - 12
2- IC4013
IC NE555
3- Transistor 2N3055 × 2
4- Capacitor 200mf
2mf / 400V
10kpf × 2
220kpf
100mf / 25V
5- Diode. IN4002 × 2
IN5406 × 2

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Tuesday, 22 March 2016

Solar Photovoltaic Cell (PV)

A solar cell , or photovoltaic cell (PV), is a device that converts light into electric current using the photovoltaic effect . The first solar cell was constructed by Charles Fritts in the 1880 . The German industrialist Ernst Werner von Siemens was among those who recognized the importance of this discovery. In 1931, the German engineer Bruno Lange developed a photo cell using silver selenide in place of copper oxide , although the prototype selenium cells converted less than 1% of incident light into electricity. Following the work of Russell Ohl in the 1940s, researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created the silicon solar cell in 1954.These early solar cells cost 286 USD/ watt and reached efficiencies of 4.5–6%.

Solar Energy

Solar power is the conversion of sunlight into electricity, either directly using photovoltaic (PV), or indirectly using concentrated solar
power (CSP). Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Photovoltaic convert light into an electric current using the photovoltaic effect .
The International Energy Agency projected in 2014 that under its "high renewables" scenario, by 2050, solar photovoltaic and concentrated solar power would contribute about 16 and 11 percent, respectively, of the worldwide
electricity consumption , and solar would be the world's largest source of electricity. Most solar installations would be in China and India. Photovoltaic were initially solely used as a source of electricity for small and medium- sized applications, from the calculator powered by a single solar cell to remote homes powered by an off-grid rooftop PV system. As the cost
of solar electricity has fallen, the number of grid-connected solar PV systems has grown into the millions and utility-scale solar power stations with hundreds of megawatts are being built. Solar PV is rapidly becoming an inexpensive, low-carbon technology to harness
renewable energy from the Sun.
Commercial concentrated solar power plants were first developed in the 1980s. The 392 MW Ivanpah installation is the largest
concentrating solar power plant in the world, located in the Mojave Desert of California . The 579 MW Solar Star , near Rosamond, California , is the world's largest PV power station .

Monday, 21 March 2016

MOSFETs

Power MOSFETs
A metal oxide semiconductor Field Effect Transistor (MOSFET) is combination of field effect concept and MOS technology.
The MOSFET is three terminal (gate, drain, source) four layer semiconductor device. MOSFET is a majority carrier device and as the majority carrier have no recombination delays, the MOSFET achieves extremely high bandwidths and switching times.
Working of Power MOSFETs
When gate is positive with respect to source an accumulation layer is formed in the layer channel as figure below. This accumulation layer is formed because of Vgs . The gate terminal(metal) is positive. The other side of oxide layer is p-type of body region.

Application of Power MOSFETs
(1) They are used in input amplifiers in oscilloscope and electronic voltmeters.
(2) They are used in logic circuits, for mixer operation of FM and TV receiver.
(3) They are used as voltage variable - resistors in computer memories.