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Anglicky v odborných předmětech "Support of teaching technical subjects in English“. Educational program: Mechanic - electrician Title of program: Technical training II. class NF amplifiers Worked out : Bc . Chumchal Miroslav.
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Anglicky v odborných předmětech"Support of teaching technical subjects in English“ Educational program: Mechanic - electrician Titleof program: Technicaltraining II. class NF amplifiers Workedout: Bc. Chumchal Miroslav Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/04.0002 je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.
Nf amplifiers Definition of amplifiers Parameters of amplifiers Classification of amplifiers Block scheme Measuring comments Students activities
What is the nf amplifier ? Amplifier is an electronic device, which is intended to amplification of electrical signals. It is a part of electric circuits, which has got two input clips ( positive clip +, negative clip - ) and two output clips. ( the same polarity as at input clips ). On input clips is bringing input voltage Uin. , ( input signal), which amplifying the amplifier and on the output we measure an amplify input voltage Uout. ( output signal ). Input and output voltage is in the V ( volts ).
Amplifiers parameters - Response of amplifier - Amplification – rate of input and output • Maximum performance • Input impedance – resistance, which is on input of the amplifier ( the bigger is the better ) • Output impedance – internal resistance on output of the amplifier ( the smaller is the better ) • Width of band – ability to amplify a wide range of frequencies • Brum • Voltage frequency characteristic
Classification of amplifiers • According to the type and frequency of input signal- nf, vf, pulse, ss, operating • According to the size of input signal – preamplifiers, power amplifiers • According to the number of stages – single– stage, multistage • According to the width of transmitted frequency bond- narrowband, broadband • According to the links between amplifications stage- direct link, with RC link • According to the position of the operating point– Class A,B,AB,C • According to the connection of transistors– SE,SB,SK
Comments to the measuring • Amplifiers supplying from the stable laboratory´s sources with small internal resistance. • Input values will be labeled by index1. • Output values will be labeled by index 2. • Output voltage bringing to the load resistance RZ ( appliance ). • Output power of the amplifier is given by: P = U22/R z ( W,V,Ω )
Questions for students 1.Question – For what serve us nf. amplifiers? 2.Question – What is the response of the amplifier? 3.Question – How to calculate performance of the amplifier? 4.Question– What parameters including vertical and horizontal axis of frequency characteristic of the amplifier?
Practical task for students • Properly connect mesuring devices on input and output of the amplifier according to the block scheme. Attention to the polarity of the measuring devices. • At a given scheme correctly determinate polarity of the elecetric capacitors.
Literature used • Poznáváme Elektroniku I.,Václav Malina, Vydalo nakladatelství KOPP,České Budějovice, 1996 • www.google/Wikipedie - zesilovače • Vlastní poznámkový sešit