@otto

You may already know all this, and if you do, please ignore.

The Yoke in the TV with the ferrite core and its windings, and the internal two oddly wound coils serve a very distinct purpose. (Notice I am NOT talking about the rgb coils here, just the main yoke)

Any electron beam created spreads rapidly, causal that the electrons composing the beam share the same charge. In essence, they repel each other. This sucks if you need a good tight beam hitiing just a few phosphorescent dots on the screen, instead of thousands of dots at once. The yoke provides a magnetic field with a small aperture (hole in the field) in the middle, which keeps the electrons from spreading. This accounts for the cores and their coils.

However, the beam needs to be focusable at more than one spot on the screen. Therefore, they provided deflection coils to manipulate the position of the aperture. IE the funky shaped coils is the center of the yoke deflect the hole in the field, moving the electron beam.

It should be obvious that we are talking quite ingenious magnetic field manipulation here.

The coils on the core may well be for a rotating field.... this I don't know. It does seem that a rotating field would provide better electron beam cohesion, as there would be less field distortion, and greater field strength at any point at any particular time.

The center coils definitely are not.

Paul Andrulis

@otto

I found a 1973 patent a few days ago which I have uploaded here. It may or may not apply directly since it was destined for demagnetizing seismic measurement coils but I have a feeling it has some bearing on the your yoke TPU. It is using two frequencies.

We are usually looking to pulse dc from zero to maximum voltage as fast as possible, taking into account the speed at which the core can actually reach saturation, then reach desaturation, etc.. What if you should leave the dc at maximum and just demagnetize it to make the pulses. Does pulsing a DC and demagnetizing a steady DC do the same thing? I think the later would equal more a real magnet. So if the DC saturates the core, and the frequencies are actually a pulsed demagnetizer, what would the secondary do in the midst of so much flux swing? Make lot's of juice. Just another perspective.

http://www.overunity.com/index.php?action=tpmod;dl=get87

Otto

"If you want a really good TPU just use iron powder cores"

http://jnaudin.free.fr/systemg/html/systest.htm

Wings

same ?

http://www.google.com/patents?id=jyIhAAAAEBAJ&dq=Robert+Craven+and+James+E.+Smith

 
http://www.google.com/patents?vid=USPAT3646562

Any electron beam created spreads rapidly, causal that the electrons composing the beam share the same charge. In essence, they repel each other. This sucks if you need a good tight beam hitiing just a few phosphorescent dots on the screen, instead of thousands of dots at once. The yoke provides a magnetic field with a small aperture (hole in the field) in the middle, which keeps the electrons from spreading. This accounts for the cores and their coils.

However, the beam needs to be focusable at more than one spot on the screen. Therefore, they provided deflection coils to manipulate the position of the aperture. IE the funky shaped coils is the center of the yoke deflect the hole in the field, moving the electron beam.

Paul,

When you have some time could you please direct me to an information source that agrees with the above statement?

Thanks,

John

@All

I thought I had a solid ground in CRT operation. At least scopes, B&W and also the Trinitron method. I must have some understanding as I've performed repairs and builds on all three.

My understanding:
The idea of a moving/resizing aperture didn't match what I understood. It (if it is an aperture) doesn't move. The strength of the field varies which causes a variation in deflection of the beam.

The beam spreads? I know this is in some text books as 'like charges repel' but the application of that term is incorrect as these are 'moving charges'. Not only moving but moving in the same direction at the same speed therefore they attract and the beam does not spread wildly.

The latter is where the laws of magnetics are hopelessly screwed as the theories of Gassman(sp?) were used instead of Ampere's correct experimental results by the folks that mistranslated the treatise on magnetics.

This is one I battle frequently and found true during short-circuit tests almost 30 years ago.

Like charges travelling parallel attract
Like charges travelling anti-parallel or not moving repel

Unlike charges travelling parallel repel
Unlike charges travelling anti-parallel or not moving attract

It is in some books this way just not many.

I expect arguments on this but I won't as the reality of jumping buss bars and cables during a short circuit can't be denied. Neither can that single dot on the screen when the beam is emitted from a fairly broad cathode element yet winds up as a tiny dot on the screen - even when the magnets, charged plates and coils have been turned off.

I don't mean to insult or start a heated discussion. The description of CRT operation just seemed very wrong to me.

Hello,

I have removed all the original coils and the glue.. Im using only the iron powder cores. The most time Im using only a quarter or half of the yoke because then I can quickly remove the controls and wind new ones.

I pulsed also the complete yokes. A fine light but there was no collector and so I made one with lamp wire. Just a few turns. I have 1 yoke that is complete with the coils - intact and working. Hmmm....I said already that this yokes looks like a TPU but without  the collectors.

I think that I can learn a lot with this strange coils. Its easy to work with this cores. Only a few turns for the collector and for the control coil and thats it! In a short time you can easily change your controls or collectors.

Please, when you play with such a TPU be careful because there is a really big current. Dont pulse the coils without a load and maybe it would be clever NOT to connect your scope on this f...g TPU. The scope probe can be near the TPU and you will see the same signals at lower voltage settings.

Otto