14-11-2012, 11:30 AM
ELECTRONIC DEVICES AND CIRCUITS
[attachment=39345]
ELECTRON DYNAMICS AND CRO:
Motion of charged particles in electric and magnetic fields. Simple problems involving electric and magnetic fields only. Electrostatic and magnetic focusing. Principles of CRT, deflection sensitivity (Electrostatic and magnetic deflection), parallel and perpendicular electric and magnetic fields
Deflection of Electrons in a Uniform Electric Field
Consider an electron beam directed between two oppositely charged parallel plates as shown below.
With a constant potential difference between the two deflecting plates, the trace is curved towards the positive plate.
Measuring d.c. Potential Difference
switch off the time-base
a spot will be seen on the c.r.o. screen
d.c. to be measured is applied to the Y-plates
spot will either deflected upwards or downwards
deflection of the spot is proportional to the d.c. voltage applied
Measuring a.c. voltage
switch off the time-base
a spot will be seen on the c.r.o. screen
a.c. to be measured is applied to the Y-plates
spot will move up and down along the vertical axis at the same frequency as the alternating voltage
spot moves to the top when the voltage increases to its maximum (positive)
spot moves to the bottom when the voltage decreases to its lowest (negative)
Measuring Short Time Intervals
Set time-base to its lowest frequency range
Connect microphone to the Y-input
Blow two short whistles into the microphone
two short pulses, at short interval apart will be displayed on the c.r.o. screen
[attachment=39345]
ELECTRON DYNAMICS AND CRO:
Motion of charged particles in electric and magnetic fields. Simple problems involving electric and magnetic fields only. Electrostatic and magnetic focusing. Principles of CRT, deflection sensitivity (Electrostatic and magnetic deflection), parallel and perpendicular electric and magnetic fields
Deflection of Electrons in a Uniform Electric Field
Consider an electron beam directed between two oppositely charged parallel plates as shown below.
With a constant potential difference between the two deflecting plates, the trace is curved towards the positive plate.
Measuring d.c. Potential Difference
switch off the time-base
a spot will be seen on the c.r.o. screen
d.c. to be measured is applied to the Y-plates
spot will either deflected upwards or downwards
deflection of the spot is proportional to the d.c. voltage applied
Measuring a.c. voltage
switch off the time-base
a spot will be seen on the c.r.o. screen
a.c. to be measured is applied to the Y-plates
spot will move up and down along the vertical axis at the same frequency as the alternating voltage
spot moves to the top when the voltage increases to its maximum (positive)
spot moves to the bottom when the voltage decreases to its lowest (negative)
Measuring Short Time Intervals
Set time-base to its lowest frequency range
Connect microphone to the Y-input
Blow two short whistles into the microphone
two short pulses, at short interval apart will be displayed on the c.r.o. screen