Make vector CRT from standard one?

[matthewray2b]

I'm curious if there is a way to convert a standard home-CRT (I have a few cheap ones from the early 2000s) into an oscilloscope. I've done a little research and couldn't find much info to get me anywhere.

My goal is to play some Vectrex games or possibly run Asteroids on it.

I've got all summer ahead of me. Just wrapped up my sophomore year as an electrical engineering student in college so I figured this would be a fun project.

[Hawkwind]

I remember Ads in the back of magazines on how to convert a TV into an O'Scope. Saw one at an Alternator repair/rebuild shop in the '80s...

[old_tv_nut]

Originally Posted by Hawkwind

I remember Ads in the back of magazines on how to convert a TV into an O'Scope. Saw one at an Alternator repair/rebuild shop in the '80s...

I could imagine this working with TV yokes for audio bandwidth applications, but I suspect not useful for higher frequencies because of too-high inductance.

[zeno]

One problem is normal CRT's have low retention, scope tubes are high. Picture a dot starting slowly on one side & fading out as it goes. In the olden days there were projects to turn a B&W into a scope.
The other problem is messing with a SS set, you will probably toast many
hoz outputs ! It would be an interesting project but I wouldnt spend
any $$ on it. Alt is keep the normal scan rates & feed it much
like a monitor at the video outs. You will uses low level voltages at that
point & not burn things up.

73 Zeno
LFOD !

[init4fun]

Not sure if this is exactly what your lookin for, but here is a video on making a TV/Scope.....

https://www.youtube.com/watch?v=-6CdJQ_Cs_E

[old_tv_nut]

I believe I've seen some attempts - have to go searching. I believe it's difficult to get the bandwidth and sensitivity you need at a reasonable power level with magnetic deflection [Edit: using the TV deflection yoke, that is].

The horizontal winding is designed to be mainly inductive at 16 kHz, so you can drive it with a switch (horizontal output tube or transistor) applying either full B+ supply voltage or open - the inductance then creates the current ramp to scan the beam from center to right, where the output device switches off. The inductance then resonates for a half cycle and reverses current through the damper diode to scan from left to center. Thus, the driver device and damper diode have relatively little dissipation during the fraction of a microsecond while they are switching from on to off. To produce a vector drive, you will need a class A driver with tremendous dissipation.

The vertical winding is normally operating with drive that is partially or mostly resistive and partially inductive with a class A drive, but develops some inductive kick. That's at 60 Hz. To drive it faster for vector use, the inductive effect will become much more prominent.

I'm not saying this is not a worthwhile project, but its major worth may be successfully doing the design calculations to see if it's paractical or not before you pick up a soldering iron.

Edit: above discussion applies to trying to use the existing deflection components. I'm not familiar with the yokes used in vector CRT games, but if you could obtain one or somehow get the specs, you woud have a better chance.

[luRaichu]

Originally Posted by matthewray2b

I'm curious if there is a way to convert a standard home-CRT (I have a few cheap ones from the early 2000s) into an oscilloscope. I've done a little research and couldn't find much info to get me anywhere.

Dude. There are so many tutorials out there. When I was at the US Trademark & Patent office they had a book in the gift shop which contains instructions for converting a B/W CRT to an o-scope. (Don't know about color CRTs though)

Originally Posted by matthewray2b

My goal is to play some Vectrex games or possibly run Asteroids on it.

For that you need to essentially create a vectorscope (both X and Y axis instead of just one). However, unless you own a Vectrex mainboard or something I don't know how you would drive such a thing for games.

[Alex KL-1]

In general... That's all need is linear current amps for H and V deflection coils. But, really for TV, like tv-nut said, coils are optimized for normal usage, so the H and V current amps will need to differ in the current and voltage levels, due to different inductances involved. A true vector one probably uses same H and V inductance values, or at least the most close possible values.