cathode ray oscilloscope and related experiments

a) Fourier analysis b) Resonating LCR circuit with damping effect

Cathode ray oscilloscope and related experiments.

Trisha Banerjee @ 2010

Inside construction

Numbers in the picture indicate: 1. Deflection voltage electrode; 2. Electron gun; 3. Electron beam; 4. Focusing coil; 5. Phosphor-coated inner side of the screen


Focus controlIntensity control

Time base control



Examples of use

Moving the initial line up and down


Pictures of use

Heterodyne AC hum on sound

Sum of a low-frequency and a high-frequency signal.

Bad filter on sine.Dual trace, showing different time bases on each trace


Oscilloscopes are commonly used when it is desired to observe the exact wave shape of an electrical signal. In addition to the amplitude of the signal, an oscilloscope can show distortion and measure frequency, time between two events (such as pulse width or pulse rise time), and relative timing of two related signals. Some modern digital oscilloscopes can analyze and display the spectrum of a repetitive event. Special-purpose oscilloscopes, called spectrum analyzers, have sensitive inputs and can display spectra well into the GHz range. A few oscilloscopes that accept plug-ins can display spectra in the audio range.Focus control

This control adjusts CRT focus to obtain the sharpest, most-detailed trace. In practice, focus needs to be adjusted slightly when observing quite-different signals, which means that it needs to be an external control. Flat-panel displays do not need a focus control; their sharpness is always optimumIntensity control

This adjusts trace brightness. Slow traces on CRT 'scopes need less, and fast ones, especially if they don't repeat very often, require more. On flat panels, however, trace brightness is essentially independent of sweep speed, because the internal signal processing effectively synthesizes the display from the digitized data.


Timebase ControlsThese select the horizontal speed of the CRT's spot as it creates the trace; this process is commonly referred to as the sweep. In all but the least-costly modern 'scopes, the sweep speed is selectable and calibrated in units of time per major graticule division. Quite a wide range of sweep speeds is generally provided, from seconds to as fast as picoseconds (in the fastest 'scopes) per division. Usually, a continuously-variable control (often a knob in front of the calibrated selector knob) offers uncalibrated speeds, typically slower than calibrated. This control provides a range somewhat greater than that of consecutive calibrated steps, making any speed available between the extremes.

Horizontal position controlThe horizontal position control moves the display sidewise. It usually sets the left end of the trace at the left edge of the graticule, but it can displace the whole trace when desired. This control also moves the X-Y mode traces sidewise in some 'scopes, and can compensate for a limited DC component as for vertical position.


Object :-a) Finding the Fourier harmonics by using the Fourier analysis.

Apparatus:- ac generator , CRO, Fourier kit.

b) To study the series and parallel LCR circuit and plot the resonance curveat constant frequency and capacity.

Apparatus: LCR kit , inductance coil.


Ac frequency generator

Fourier wave form type kit

CRO

a)


Fourier analysis experiment whole setup

Air core inductance (for studying the resonating in LCR and its damping effect)

Resonating circuit kit

b)


Some of the brief features and experiment data of LCR resonant circuit

1) Circuit diagram for series LCR :-


Graph representationSeries LCR having max current at cont capacity 700pF

Series LCR having max current at cont frequency at 50 Hz


2) Circuit diagram for parallel LCR:-


Graph representationParallel LCR having max current at cont capacity 700pF

Parallel LCR having max current at cont frequency at 50 Hz


cathode ray oscilloscope and related experiments

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