7/29/2019 Exp1_BW_TV_BLK_DIA

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SUBJECT:

Video Engineering

TITLE:

To study the block diagram of a Black & White T.V. receiver 1

EXPERIMENT NO. 1 DATE:

DOC. CODE: AITS/ECD/EXPT/602

REV. NO.: 1.01

Experiment No. 1Aim: - To study the block diagram of a Black & White T.V. receiver.Theory: -

The block diagram of a 20 B/W T.V. is shown in Fig-1. The function of a T.V.receiver can be divided into following sections:

(1) TUNER: -Incident R.F. Signal (from Antenna) at the Tuner first passes through a high pass

filter, which prevents unwanted frequencies from interfering with the tuner and I.F.stages. The received signal is amplified by the R.F. Amplifier and further converted in themixer amplifier stage to yield the intermediate picture and sound I.F. signals (CompositeI.F. Signal) by heterodyning with local oscillator frequency.

(2) VISION I.F: -The composite I.F. signal is applied to Video I.F. subsystem, using I.C. CA3068,

where it is further amplified and detected to give the composite video signal (CVD) and

intercarrier sound I.F. Of 5.5 MHz, Amplification of both the R.F. signal in the tuner andI.F. signal in the I.F. stage is controlled with suitable Automatic Gain Control (AGC)arrangement which ensures a constant Video output over a large range of video signalstrength (typically 100dB). The required AGC voltages for the tuner and I.F. aregenerated in the I.F. subsystem CA3068. The composite video signal is then applied tovideo amplifier and Sync Separator circuit in horizontal subsystem IC CA920.

(3) Sound I.F. AND AUDIO AMPLIFIER: -The 5.5 MHz sound I.F. (S.I.F.) signal is applied to sound IF and Audio amplifier

subsystem IC CA1190. This IC amplifies and detect the sound IF and further amplifies

the obtained audio to directly drive the Loudspeaker to deliver an audio about 3.0 watts.(4) HORIZONTAL OSCILLATOR & SYNC SEPARATOR: -

The horizontal oscillator subsystem IC CA920 generates the sweep for horizontaldeflection. The composite video signal is also processed to extract Horizontal an VeriticalSync information. (H. Sync and V. Sync). The separated H. Sync Pulses control the phaseof horizontal oscillator, which drives the horizontal output stage (E.H.T. Stage). V. SyncPulses are applied to the vertical oscillator.

(5) VERTICAL OSCILLATOR & AMPLIFIER: -The vertical oscillator and amplifier consist of IC UPC 1031. V. Sync Pulses appliedto IC UPC 10361 controls the phase of vertical oscillator. The vertical output stage in this

IC drives the vertical coils of YOKE.

Atmiya Institute of Technology & Science, Rajkot

7/29/2019 Exp1_BW_TV_BLK_DIA

2/3

SUBJECT:

Video Engineering

TITLE:

To study the block diagram of a Black & White T.V. receiver 2

EXPERIMENT NO. 1 DATE:

DOC. CODE: AITS/ECD/EXPT/602

REV. NO.: 1.01

(6) VIDEO AMPLIFIER: -The composite video signal is applied to video amplifier consisting of transistor BF

195C and BD 115 to amplify it and apply to the picture tube cathode and modulate theraster to obtain the picture.

(7) HORIZONTAL AMPLIFIER & (E.H.T): -The horizontal output signal from CA920 is applied to drive the horizontal

amplifier and horizontal output stage (E.H.T), which in turn drives the horizontal coils ofYOKE and also provides anode voltage (EHT 16KV) for the picture tube. It also producesfocusing, accelerating and control grid voltages for the picture tube.

(8) SWITCH MODE POWER SUPPLY (SMPS): -S.M.P.S. stage provides the different DC voltages required for various stage of

receiver Viz. +110V, +18V and +12V.

(9) PICTURE TUBE: -It converts the electrical signal into the light signal i.e. picture.

(10) LOUD SPEAKER: -It converts the electrical signal into the sound signal.

Atmiya Institute of Technology & Science, Rajkot

7/29/2019 Exp1_BW_TV_BLK_DIA

3/3

SUBJECT:

Video Engineering

TITLE:

To study the block diagram of a Black & White T.V. receiver 3

EXPERIMENT NO. 1 DATE:

DOC. CODE: AITS/ECD/EXPT/602

REV. NO.: 1.01

Grade Lab-In-Charge H.O.D.

Atmiya Institute of Technology & Science, Rajkot