Horizontal Amplifier Block Diagram

The block diagram of the horizontal amplifier is shown below in figure.

Block Diagram of Horizontal Amplifier
The horizontal amplifier in CRO deals only with the sweep frequency signals. Hence its band width requirements are not critical as that of the vertical amplifier. The horizontal amplifier handles signals of considerable amplitudes. However the gain of this amplifier must be large. The reason is the low deflection sensitivity of the horizontal deflecting plates. The gain of this amplifier must be sufficient that it produces the required sweep over the screen.

The horizontal amplifier consists of an input signal amplifier which is a single ended amplifier. This receives its input form the mode switch. The mode switch presents either the output of the internal sweep generator, or the external horizontal input signal. The CRO can be used with external signal in X-Y mode instead of the usual Y-t mode, in the external position of the mode switch. The output of the input signal amplifier is given to a paraphase amplifier which drives the push pull output amplifier. The push pull output amplifier presents the positive and negative going ramp voltages of the required amplitude to the two deflecting plates. (Horizontal). This ensures simultaneous application of voltages to the deflecting plates. Along with the sweep voltage an offset voltage also is presented to the input signal amplifier. This D.C offset voltage positions the spot on the screen of the cathode ray tube.


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