hey this is how cro works i explained it throughly
cathode ray oscillascope. has 6 parts.
the filament: it goes through thermionic emiision(where a substance is heated it releases electrons) this filament is heated and releases electorns with negative charge.
the anode grid: it has a positve charge. this controls the nrightness (ill tell u how later)
the cathode grid: it has a negative charge, this allows the beam of electron (the electrons emitted when tht filament was heated)
the y plates:hese have plates with (+) and (-) charge and are attached vertically to each other on the tube of the CRO. this helps the beam of electrons move up and down so the beam of electrons spread evenly (up and down) on the screen.
the x plate: these have plates with (+) and (-) charge and are attached horizontilly to each other on the tube of the CRO. these help the electrons move (left and right) as it hits the screen.
the screen: at the end of the CRO is the screen (made of fluroscent usually) when electorns hit this screen it glows.
without x plate and y plates u will see the beam of electrons hitting one point of the screen only (so only tht part glows) for eg:on TV (just an example) , if with out x plates and y plates, picture can only be seen as a spot of light (picture) on the screen. but with x and y plates the electrons are able to reach both (up and down) and (right and left) with the help of y plates and x plates respectively. (ill tell u how they work later))
how does the OCR work?
first the filament is heated, beams of electrons are emitted (this is callerd thermionic emission). they go throu the cathode. what does cathod do? Cathode are negatively charge (-) and so are the beam of electrons, so repulsion take place due to similar charges allowing some beams of electrons to "stay back". This control the brightness cuz "the more number of electrons hittin the screen, the brighter the pic comes on the screen". ok, then the beams pass through the anode. what does the anode do? Anode is positively charged (+) and the beam of electrons are oppesitely charged. this anode atracts the beam of electron giving the "boost" or "acceleration" and to travel in a straight line (beam). then it reaches the Y plates. as i told u the help the electrons move up and down . they are plates with voltages (charged with (+) and (-))). they are GIVEN WITH A.C VLTAGE because if it was D.C then the elctrons would only move up OR down depending on the position of the positively charged plate ( as beam of electron is negatively charged). u see, A.C current changes its direction so the plates change their charges, whic means (+) become (-) then later (-) becomes (+). so (+) charge changes its positon and so does the beam of electron which changes its direction of deflection. this helps the electrons to touch both up and down of the screen.
the X plate are same, except they help the electrons to move right and left they are also charged except tht they are aranged horizontally. they are time base. the work with time, how? by letting the voltage between these plates go 0 then after sometime go to a certain value. how tghis helps? as the voltage has acertain value thts not 0 the beam deflects to towards positively charged plate. then when after a certain time it the voltage goes 0 immediately. this all ows the beam of electrons to GO BACK its old path (which was before deflection at X PLATE), then vise versa. this helps the electrons go left and right on the screen.
U might ask what in x plate there is time base and in y plates are AC current? why cant the put AC on the xplates too? This is because i think tht the time base system helps beam to go in the REQUIRED or aprropriate horizontal path.
then finally the electrons reaches the screen in every direction (with the help of x and y plates) which causes the whole fluroscent screen to glow or lit.
however i donthink we have any calibrations or how does it show them as graph explainations in our syllabus..
any help needed or any confusion im all here m8....
i hope this helpd
