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Serene_Potato

On Cathode Rays TVs...

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Wondering how the cathode ray sweeps across the TV screen so quickly.

All the websites that I looked at only went as far as saying "sweeping across the screen row by row 24-60 times a second"

But how does it "sweep" across the screen so quickly?

I know it's done with some sort of "magnetic yoke", but how is that thing manipulated with such speed?

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Magnets are actually electromagnets, shape of magnetic field can be varied instantaneously by changing applied electrical current. 

 

So how many electromagnets are there for it to display with such precision?

And I saw from an example TV (taken apart so we can see the tube) that there are no moving parts, so how does it cycle through the magnets to bend the cathode ray in rows?

Sorry, I'm a bit dumb in this area of electronics.

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So how many electromagnets are there for it to display with such precision?

Sorry, I'm a bit dumb in this area of electronics.

AFAIK, two. One for X axis, one for Y axis. The precision comes from the ability to control the field/current, not the number of magnets inducing the field.

 

Seeing as you edited the question, I'll go into a bit more detail. A charged particle moving through a magnetic field has a force applied on it, and is deflected proportionally to the force of the magnetic field (and the mass/charge ratio of the particle). Both electromagnets are used at once, and and you get a deflection force that is a linear combination of the two forces (high school physics).

By altering the strength of the magnets using an electronic control you can "steer" the electron beam with a degree of precision directly related to the control you have over the current powering the magnets. No moving parts required. As for exactly how the current powering the magnets is controlled, thats waaaay outside my wheelhouse, but I do know it involves a transistor chip (or a vacuum tube in really old sets).

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AFAIK, two. One for X axis, one for Y axis. The precision comes from the ability to control the field/current, not the number of magnets inducing the field.

 

Seeing as you edited the question, I'll go into a bit more detail. A charged particle moving through a magnetic field has a force applied on it, and is deflected proportionally to the force of the magnetic field (and the mass/charge ratio of the particle). Both electromagnets are used at once, and and you get a deflection force that is a linear combination of the two forces (high school physics).

By altering the strength of the magnets using an electronic control you can "steer" the electron beam with a degree of precision directly related to the control you have over the current powering the magnets. No moving parts required. As for exactly how the current powering the magnets is controlled, thats waaaay outside my wheelhouse, but I do know it involves a transistor chip (or a vacuum tube in really old sets).

Thanks so much, the part about the electronic control was the part I was missing about how this whole thing worked. :D Any idea what it's called (so I can also figure out how that works)?

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AFAIK, two. One for X axis, one for Y axis. The precision comes from the ability to control the field/current, not the number of magnets inducing the field.

 

Seeing as you edited the question, I'll go into a bit more detail. A charged particle moving through a magnetic field has a force applied on it, and is deflected proportionally to the force of the magnetic field (and the mass/charge ratio of the particle). Both electromagnets are used at once, and and you get a deflection force that is a linear combination of the two forces (high school physics).

By altering the strength of the magnets using an electronic control you can "steer" the electron beam with a degree of precision directly related to the control you have over the current powering the magnets. No moving parts required. As for exactly how the current powering the magnets is controlled, thats waaaay outside my wheelhouse, but I do know it involves a transistor chip (or a vacuum tube in really old sets).

 

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