What is Crt: Definition and 36 Discussions

A CRT projector is a video projector that uses a small, high-brightness cathode ray tube as the image generating element. The image is then focused and enlarged onto a screen using a lens kept in front of the CRT face. The first color CRT projectors came out in the early 1950s. Most modern CRT projectors are color and have three separate CRTs (instead of a single, color CRT), and their own lenses to achieve color images. The red, green and blue portions of the incoming video signal are processed and sent to the respective CRTs whose images are focused by their lenses to achieve the overall picture on the screen. Various designs have made it to production, including the "direct" CRT-lens design, and the Schmidt CRT, which employed a phosphor screen that illuminates a perforated spherical mirror, all within an evacuated "tube."
The image in the Sinclair Microvision "flat" CRT is viewed from the same side of the phosphor struck by the electron beam. The other side of the screen can be connected directly to a heat sink, allowing the projector to run at much brighter power levels than the more common CRT arrangement.Though systems utilizing projected video at one time almost exclusively used CRT projectors, they have largely been replaced by other technologies such as LCD projection and Digital Light Processing. Improvements in these digital video projectors, and their subsequent increased availability and desirability, resulted in a drastic decline of CRT projector sales by the late 2000s. As of 2012, very few (if any) new units are manufactured, though a number of installers do sell refurbished units, generally higher-end 8" and 9" models.
Some of the first CRT projection tubes were made in 1933, and by 1938 CRT projectors were already in use in theaters.

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  1. A

    CRT gun "dissection" questions

    While messing around with old tv's I had a Panasonic sent the innards to recycling but at the factory kept some souvenirs , broke off the electron gun from the tube (that sweet swoosh sound when the air rushes to fill the vacuum). So long story short I know the basics of how an electron gun...
  2. A

    Is there a way to improve CRT raster scan efficiency by scanning both ways?

    Someone surely has though of this before but I still wonder. The original electron gun raster scan pattern was from top left to right and then the gun is switched off while the deflection coils reset so that the electron beam would start again at the left side but now a pixel row or two (as in...
  3. A

    I How does the raster scan frequency affect the accuracy of a CRT TV picture?

    I couldn't find any information on this but I do wonder, what was the average CRT raster scan line thickness in terms of pixels illuminated in each full scan from left to right? Did the electron beam illuminate a line that is just a single pixel width on each pass or did it hit multiple pixel...
  4. A

    Analog TV signal, CRT workings

    I had a talk with a friend of mine , just wanted to make sure I'm not wrong. I actually have one older CRT set with an open back in another room so I went to check my "question" out a bit before asking. 1) Is it right that the video signal (after some input demodulation etc boards) directly...
  5. RamSkull

    Are CRTs Suitable for Use in Ion Thrusters?

    Hello! I'm trying to make a simple ion thruster that will be used in a science fair so I'm not concerned about its efficiency but just creating at least some thrust. However I wanted to make it as close as reality as possible, using every component and respecting its details if possible. Ion...
  6. Zahid Iftikhar

    Collimation of an Electron Beam by the Anode of a CRT

    Please help me in understanding the function of anode. As in image attached you see, once the electron beam is emitted from cathode and filtered by grid, it enters into the one or series of anodes. As anode is positively charged, so, to my understanding it has no electric field inside its hollow...
  7. F

    Chinese remainder theorem (CRT) question, flat shapes

    Homework Statement By hand, find the 4 square roots of 340 mod 437. (437 = 23 * 19). Homework Equations Chinese remainder theorem (CRT) The Attempt at a Solution So this is the wrong way I did it was first I solved ##x^2 \equiv 340 (\operatorname{mod} 19)## and ##x^2 \equiv 340...
  8. prashant singh

    What Happens When You Connect a 10,000 V Supply to a Normal Tube Light?

    suppose I connect a 10,000 v supply to a normal tube light. what will happen? will it behave like a cathode ray tube or something else
  9. A

    Energy conservation and particle acceleration

    As i am a physics amateur and most of what i learned is through videos, i sometimes get confused about energy conservation, my question concerns particle acceleration in CRT for example, we create a potential difference ( which requires energy) between the anode and the cathode, then the...
  10. Blackhawk4560

    Force on electron passing through Electric Field (calculate)

    Good afternoon, I hope this is in the right place... Anyway, diving right in- Say I have a classic CRT- How do I calculate the energy, in eV, that the electrons have upon reaching the anode? Also, is there a way to derive the speed of the electrons as well? See the attached image to...
  11. thankz

    Anyone have a old vga crt schematic?

    I need to tear down (at least on paper) an old computer monitor, I you've got schematics to one that'd be great, even better if it still has data sheets around for the ic's. just for learning purposes :woot:
  12. R

    Artificial Magnetic Fields – Electromagnetism (Grade 12) -- CRT e-beam deflection

    Homework Statement A cathode-ray tube aims electrons parallel to a nearby wire that carries current in the same direction. What will happen to the cathode rays in terms of deflection? The Attempt at a Solution [/B]The Motor force deflects the cathode rays ?
  13. D

    Magnet vs CRT TV a.k.a question about magnetic poles of electrons

    When watching some videos about neodymium magnets, I came upon a very interesting phenomenon. Namely, the maker of the video put a large magnet near an old CRT TV. At first, a big black spot appeared on the screen. This means that the electrons were repelled from from the magnet and didn't...
  14. C

    Calculating Electron Deflection in CRT

    Homework Statement In the cathode-ray tube, electrons having a mass m are emitted from a source point S and begin to travel horizontally with an initial velocity v0. While passing between the grid plates a distance l, they are subjected to a vertical force having a magnitude eV/w, where e is...
  15. mishima

    Radiation pattern of crt tv with small loop antenna

    I was playing with an old crt TV and a small loop antenna earlier and noticed that when I hold the antenna vertically in front of the TV I get one solid spike at around 15 kHz. When I hold the antenna horizontally I get a multitude of spikes that are not there when I turn off the TV. This...
  16. E

    Where do the electrons go in a CRT

    Do electrons flow in a "circuit" in a CRT? When they hit the phosphor coating on the screen, does the final anode complete the circuit and allow current to flow back to the circuitry or does the anode only serve to accelerate the electrons which then "accumulate" by combining with the phosphors...
  17. P

    How to Remove Electron Gun from CRT?

    Hey... I was just thinking... Does anyone know how to extract the electron gun from an old CRT so that it is left intact? Basically, I want to remove it so that I can play with the electron beam/use it for other experiments/ etc. Please tell me.
  18. W

    Induction coil powering a crt: how does it work?

    A professor the other day used an induction coil power a crt tube like the one at the link below. http://chemteacher.chemeddl.org/services/chemteacher/index.php?option=com_content&view=article&id=99 I understand the general idea of both induction coils and crts, but what confuses me is...
  19. T

    Electrical Can a Cathode Ray Tube be Used to Build a DIY Mass Spectrometer?

    I'm wondering if it would be plausible to use a cathode ray tube (crt) style monitor to build my own mass spectrometer. Unfortunately, commercial models are prohibitively expensive, but if I had plans or at least a good idea of how to build one, I have the nagging feeling I could. My idea is as...
  20. N

    Solve System of Congruences Using CRT

    Hi, i know how to do the CRT but I'm kind at a loss with this one. Can anyone help me please? Explain why the Chinese Remainder Theorem does not apply directly to the following system. x = 5 mod 6 x = 17 mod 21 Determine an equivalent system of equations to which the CRT applies and...
  21. M

    No Picture on the CRT Television

    All of a sudden the picture on my Panasonic CRT television disappeared, but the sound remained. The most common cause of the picture disappearing is a faulty tube and the warning sign of this can be seen for some while. So it can't be the tube. There was a funny burning type smell from the...
  22. S

    What is the deflection of an electron in a CRT with given parameters?

    Homework Statement An electron with an initial speed of 7x106m/s is projected along the axis midway between the deection plates of a cathode-ray tube. The uniform electric field between the plates has a magnitude of 1000 V/m and is upward. F = 1.6x10-16N and acceleration a = 1.76x1014m/s2...
  23. A

    CRT direction of field in accelerating zone

    My textbook says that since the electrons are accelerated to the right in a CRT the field direction is to the left. This leaves me confused, because according to this model the field lines are pointing out from the electrons instead of pointing into the electrons. I thought that field lines are...
  24. S

    Deflection in a CRT: Problem more than halfway solved, stuck

    Deflection in a CRT, Potential Problem: Problem more than halfway solved, stuck Homework Statement In Fig. 24-32 an electron is projected along the axis midway between the deflection plates of a cathode-ray tube with an initial speed of 6.40 106 m/s. The uniform electric field between the...
  25. F

    What Is the Vacuum Level of a CRT TV?

    Does anyone know what the vacuum level of a CRT television is? Thanks
  26. M

    The CRT and Electron Superposition

    If according to quantum theory electrons are in superposition until their waveforms collapse by the observer observing them, does this mean that there are more than one image on a CRT such as a TV or PC screen when nobody is looking at it?
  27. A

    CRT TV Disassembly Safety: Lead & Phosphors

    I recently disassembled my Big Screen CRT projection tv. I have been well aware of the danger of the capacitors in CRT TV's and I managed to take the TV apart and remove the capacitors all without killing myself. However, I was doing some more reading online and it seems there is another danger...
  28. D

    The Chinese Remainder Theorem (the CRT)

    Find the lowest number that has a remainder of 1 when divided by 2, 2 when divided by 3, 3 when divided by 4, 4 when divided by 5, and 5 when divided by 6. It is possible to solve this by applying the general algorithm that solves Chinese Remainder problems. But, for this special...
  29. J

    Tektronix 2246 Oscilloscope CRT Sparkle/Noise - Normal?

    Hello everyone. I am new and have a question. I just got a Tektronix 2246 Mod A Oscilloscope. Everything works great on it. The CRT seems to have some "sparkle" or "noise" in it. It is very slight and it is visible both on the traces and the readout. It looks like the traces and readout...
  30. Holocene

    What should I do with my old PC and CRT monitor?

    Since building my new system, this is just sitting around, and I doubt I'll ever use them again. Any ideas as far as disposal? The monitor works fine, but there isn't too much on the PC worth salvaging. Just thow it in the garbage or what?
  31. brewnog

    Accuracy of a CRT oscilloscope

    Anyone got any experience? Don't need anything with the accuracy of a CRT oscilloscope but ease of setup, repeatability, portability and convenience are more important.
  32. H

    Plates in a CRT and how they become charged

    I just am trying come up with a hypothesis regarding the plates in a CRT system? How do they become charged? Looking at when an electron travels between the two plates, say the plates are on the top and bottom and the top plate is positively charged and the bottom is negatively charged, we...
  33. S

    Do CRT Monitors Emit Radiation?

    Is it true that CRT monitors emit radiation? If they do is it harmful?
  34. K

    Sensitivity to CRT Televisions ?

    I've got a question about CRTs... Is it normal for them to emit this low wining/ringing sound even after start up? It's annoying and headache inducing. My old TV became really bad with this, it was as if it was crying for blood ha, so I got a new one (also a CRT) and the same problem popped...
  35. B

    Relevance of CRT to this question

    Q. Use the chinese remainder theorem to find the inverse of 32 (mod 3 * 5). The question's wording seems to suggest that using the CRT to find the inverse is faster or computationally easier than solving 32x \equiv 1\left( {\bmod 15} \right). I don't see how this is so. In any case if I am...
  36. C

    CRT Accelerating & Deflecting Voltages

    Our Physics review sheet includes two questions involving "accelerating voltage", "deflecting voltage", and "screen deflection", which are involved with Cathode Ray Tubes. The chapter on this in the book basically outlined what one was and how it worked, but it did not make use of any of these...