Different Frequency and its Application

What is frequency ?

The number of cycles per unit of time is called the frequency. For convenience, frequency is most often measured in cycles per second, and measured in hertz  (Hz).

Frequency range 

Above chart shows frequency range from very low range to extreme range  of communication.

Also shows name of frequency and its wave length.

What is Wave length ?

A wave or sinusoid can be completely described by either its frequency or its wave length . They are inversely proportional to each other and related to the speed of light through a particular medium.  The relationship in a vaccum is show in following equation:

                  C = f *  ^

 Where C is the speed of light. As frequency increases , wavelength decreases.

Frequency Application 

555 Timer IC

Introduction

The timer IC was introduced in the year 1970 by  Signetic Corporation and gave the name SE/NE 555 timer. It is basically a monolithic timing circuit that produces accurate and highly stable time delays or oscillation. When compared to the applications of an op-amp in the same areas, the 555 IC is equally reliable and is cheap in cost. Apart from its applications as a monostable multivibrator and astable multivibrator , a 555 timer can also be used in dc-dc converters, digital logic probes, waveform generators, analog frequency meters and tachometers, temperature measurement and control devices etc.  The 555 IC be used in temperature ranges between -55 to 125 Celsius.. The 555 IC use in two modes monostable and astable multivibrator .

The important features of the 555 timer :

• It operates from a wide ranges of power supplies +5 volt to +18 volt supply.
• Sinking or sourcing 200mA of load current.
• The external component should be selected properly so that the timing intervals can be made into several minutes along with the frequencies exceeding several hundred kilo hertz.
• The output of a 555 timer can drive a transistor transistor logic(TTL) due to its high current output.

DOORDARSHAN 56 YEARS COMPLETION

The doordarshan, went live on 15 September 1959.

Some amazing facts about Doordarshan:

1. On september 15 1959, UNESCO (United Nations Education Scientific and Cultural Organization ), gave india 20,000 dollars and 180 Philips sets to start india's largest broadcasting organisation .
2. It is said that broadcasting equipment was donated by germans who had come for an industrial exhibition.
3. All India Radio(AIR) supplide floor space and initial news content to Doordarshan.
4. In the starting year of the channel , the channel had only 180 television sets. In 10 years, the no. had grown to 1250 sets. A television producing factory at kanpur had provided 1205 sets. In 1970 it grew to 2200 and by 1977 the no, had grown to a quarter million.
5. It was year 1965, doordarshan started Broadcasting news.
6. In the year 1975, Vikram Sarabhai , the father of the indian space program, suggested an Indian National Satellite (INSAT) plan to send TV signals all over india .
7. In 1976, Indira gandhi went on television to announce the separation on Doordarshan from AIR.
8. In 1965, Doordarshan began a five minute news bulletin.
9. Pratima puri was the first newsreader.
10. DD has its own free charge D.T.H service called DD Direct Plus.
11. DD india is available in 146 countries worldwide.
12. Doordarshan has over 60 channels which includes DD1,DD2,DD, Daman and Diu DD Arunachal pradesh ,DD english , DD Goa etc.
13. In 2014, Doordarshan relaunched with new theme of pink and purple . The channel was also accompained by a new punchline"Desh ka Apna Channel".

                                                      Happy 56th to Doordarshan