Band Pass Filter

Band pass filter is terminology which is used in telecommunication. Filter is device which passes or stops specific things.

 Filter:  Filter is as like net used to catch fishes or birds or beasts etc. Filter is also used for water purification. Here terminology used for filter, is for telecommunication. This filter is electronics circuit which passes or stops the specific frequency.

Band: As written up, here things are discussed are about the telecommunication. Band is range of frequencies. as like from 2 hz to 10 hz. this is called band.

Band Pass Filter: Band pass filter is electronics circuit which pass specific range of frequencies. These filters blocks the specific range frequencies or allow to pass the range of frequencies. When there is modulated signal then for transmission, one of bands or both bands are transmitted. After receiving the signal, for demodulation we have to separate the signal from carrier frequency. Here Band pass or Band stop filters are used. Mostly these filters are used in telecommunication system. Communication system can be of Radio, television, telephone etc

Automatic Transfer Switch

Automatic transfer switch or in short ATS is an electronic circuit which is attached with generator. It operates generator automatically when there is outage of power from the utility. In this circuit there are comparators which look at the line voltage and when the line voltage of utility goes down they switch on the generator and when voltage of generator get stable, they switch on the contactor of main supply to load and thus there is no need for generator operator for all time. Battery is main power source for this panel for operation or self start of generator. The other work it does, is to maintain the voltage level and if the level goes down it cut off the line and starts the generator. This is how Automatic transfer switch work.

Audio frequency

Audio frequency is frequency which can be heard by human or animals. Its range is 4k hz to 20khz. All humans and animal which have audible sound have frequency of voice in this range. The voice, which have more or less frequency than this range it can’t be heard.

In telecommunication transmission is done in high frequencies for fast transmission. These messages or data is then converted to audible frequency for hearing. As like television when its data is transmitted, it is in high frequency but when television set receive and decodes the data and convert it to visible and audible messages. it produces audible message in range these frequencies. So it is called audio frequency.

Analog-to-digital converter

Analog to digital converter is electronic circuit which  make analog signal digital. in other words we can say that ADC is basic and very important circuit in modern era of life. when we speak ,microphone  produce analog signal. this signal is then amplified and then before transmission, it is converted to digital form.

Analog signal is continuous signal as like sine wave, sawtooth wave etc while digital signal is discrete signal in the form of 1 and 0. Any of the input or analog signal is converted to digital if transmitted. There are a lot of methods to convert the analog signal into digital form. Mostly used methods are comparators. In comparator one reference voltage is given while on other terminal signal is provided. This comparator gives output if signal voltage is greater or equal to the reference as 1 and 0 vice versa. Here also keep in mind that resolution of digital signal is also important. It mean the signal you are converting into digital form, how many bits signal do you want. one bit, 2 bit,4bit,8bit,16bit  32 bit 64 bit etc. Now a days laptop and window are operation on 64 bit processors.

Amplitude modulation

Modulation is method to impose signal on carrier frequency. There are many methods to do this. Amplitude modulation is one of those methods. In this method signal and carrier frequency are mixed in such a way that amplitude of carrier frequency changes according to signal. This is very old method. In this method there is a lot of noise. in simple it is also called AM modulation. Its range according to other methods is long for transmission but there is lot of noise which is added automatically. It circuit and working is very simple. it is shown in figure.

Keep in mind when amplitude modulation is done there are two signal bands. One upper side band and other lower side band. One of these bands are transmitted some time both of the bands are transmitted and in receiver one band is suppressed and  other is demodulated to get signal. In old system of radio there was AM modulation used. Now it is also used but very rarely.

Power Amps:

Power Amplifier is electronics circuit which amplify the signal. In other words amplifier is circuit or electronic device which make week signal strong. Amplifier is an essential part of mostly used devices like, mobile , Television, Audio amplifier, CD players, tape recorders etc. In other words amplifier is important part of any system, transmission system or any other. The main        part of the amplifier is transistor an electronics  component which amplify the signal. any signal which is amplified in micro volt or amps and output is in few amps. It is said that amplifiers can amplify signal up to 1000s of times, it is true. but keep in mind it cannot be 1 volt to 1000 volt but it can be from 1u volt to 1 volt which is million times amplified.

How Amplifier works:

The working of amplifier is as we week signal is applied on the base of the transistor it makes changes in current or voltage flowing from emitter to collector of transistor. Thus voltage measure on the resistor which is connected at collector in series, is high. it is called that signal applied on base of transistor is amplified. The value of resistor in series with collector is always high rather than resistance of emitter. These resistances actually cause amplification of signal. look at figure: