ASSINGMENT 1

TELEVISION BLOCK DIAGRAMS AND FUNCTIONS

Functions of different blocks of a TV

The Black and white TV receiver has a simple circuit block diagram compared with the colour receiver. The following details describe the function of each block.

1. Tuner Unit - This section contains the RF Amp for both UHF and VHF, the Mixer, local oscillator and AFT. The RF amp amplifies the signal from the antenna, reduce the noise before passing it to the mixer which converts it into IF with the local oscillator. The AFT gives the user the option of fine tuning. This controls the local oscillator and RF amplifier circuits in the tuner.
2. RF Amplifier – This receives the Video and Audio signal from the aerial and amplifies it.
3. Mixer – This comprised of an integrator which mixes the received signal with the output from the local oscillator and to form the Intermediate Frequency.
4. Local Oscillator – This provides a frequency that is mixed with the incoming RF signal.
5. IF Amplifier – This amplifies the tuner output and regulates the local oscillator within the tuner through the automatic frequency control.
6. Demodulator – This section converts the Intermediate frequency into the original transmitted signal which comprises of both video and Audio signals
7. Video Amplifier –This section amplifies the video signal and passes it to the CRT to control the brightness at each particular point of the screen.
8. Sync Separator –This separates the synchronized vertical and horizontal sweeps of the video signal and each respective signal is directed to its timebase.
9. Horizontal Timebase –This Section Provides a saw toothed signal that will sweep across the CRT vertically for horizontal detail of the Picture. The signal is controlled by the sync separator.
10. Vertical Timebase - This Section Provides a saw toothed signal that will sweep across the CRT horizontally for vertical detail of the Picture. The signal is controlled by the sync separator.
11. The Extra Tension Voltage -This is a very high voltage that is controlled by the time bases for running the final anode of the CRT.
12. The IF amplifier and Modulator - This section receives the filtered audio signal IF and converts it to its original frequency and the transmitter.
13. Audio Amplifier – This section amplifies the modulated audio signal and drives the speaker.
14. Power Supply – This block provides a DC voltage to all functional blocks. A previous Voltage is generated for the EHT voltage supply to the CRT.
15. CRT – The Cathode Ray Tube receives a modulated video signal and with an internal electron beam which is controlled by the time bases changes the brightness at each point of the screen to give out the intended

Block diagram of a TV

Reference:

• Color Television, http://www.tdk.co.jp/teapl01/ctv ,©1996-2007 TDK Corporation. All rights reserved.

• Mono TV Receiver©http://www.hobbyprojects.com/block_diagrams.html

• Alvin A. Liff, J.A. Sam Wilson, Color and Black and White Television, Theory and Servicing, 3^rd Edition©1993 Prentice Hall Inc. upper Saddle River, NJ 07458