Anglicky v odborných předmětech "Support of teaching technical subjects in English“

1. Anglicky v odborných předmětech"Support of teaching technical subjects in English“ Educational program: Mechanic - electrician Title of program: Technical training II. class The powerful amplifiers Worked out: 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.

2. The powerful amplifier • Description of the powerful amplifier • Terminal stage with complementary couple of the powerful transistors. • Scheme K.S. (t.s.) with complementary couple of the powerful transistor. • Measuring of frequency characteristic. • Internal connection of the integrated circuit of the amplifier. • Work with catalogue • Students activities

3. Description of the powerful amplifier • Job of the powerful amplifier is deliver the required performance to the load of the amplifier ( loudspeaker ). • The performance of the amplifier is product of voltage and current P=U.I, P=U2/Rz ( W, V, Ω ). • Basic parameters: - frequency attenuation characteristic ( 20 Hz – 20 KHz ) - output performance - nonlinear shape distortion - distance - brum

4. Terminal stage with complementary couple

5. Complementary couple If we bring on the corporate base sin. signal, each of the transistor choose the own half-wave. The current passing alternating by one and than by second transistor. In emitters connection point T1, T2 arising an alternating voltage. From this point is taking an alternating voltage, performance. It is necessary to split off speaker by galvanic way through the C1 so that it would not cause the short- circuit of T1. If we connect voltage power supply, the both T is passing the standstill current which is very small. It is increasing with bringing input signal. By the both of T is passing the same current, the voltage of the source is distributing on both transistors by the same amount.

6. Measure of the frequency characteristic • Start measuring on frequency 1kHz, set up the level of signal 0 dB on output. • Select the amount of the input signal U1 so that it is equal to the half power of the amplifier. • Volume controller on max level, pith and depth controller set up on medium value of potentiometers. • Measuring on fixed frequency of acoustics band. • To the prepared table write down the resultant values. • Resultants graphically display.

7. Internal connection of the amplifier – integrated circuit Chip – miniature desk of semiconductor ( Si ), on which there is the whole connection. Necessary number of active elements, transistors, the next parts are subsidiarities circuits. It is as a protection against thermal or power overload, it automatically setting the work point. Types of the cases Size of the cases, maintenance Simplicity connection of I.O. outlet Cooling of integrated circuits

8. Students activities – control questions • Explain the function of the powerful amplifiers. • Work with catalogue, explanation of concepts in the catalogue. • Explain internal connection of integrated circuit.

9. Students activities • Interconnect pattern practice desks of voltage, correction and final stage of the amplifier. • Measure current passing through by the powerful amplifier

10. Literature used • Poznáváme Elektroniku I.,Václav Malina, Vydalo nakladatelství KOPP,České Budějovice, 1996 • Vlastní poznámkový sešit