XY Monitor / Display

Forum for discussion of electronic television. Generally, stuff to do with CRTs and not using mechanical displays.

Re: XY Monitor / Display

Postby Steve Anderson » Fri Aug 03, 2018 9:18 pm

An earlier version of this display used tubes/valves for the deflection, 12AX7s/ECC83s. Only required 1mA (as I recall) of anode current...

Because of their hi-mu of 100 they were easily driven with op-amps...

Steve A.
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Re: XY Monitor / Display

Postby Harry Dalek » Wed Aug 15, 2018 8:31 pm

Steve Anderson wrote:Electrostatic CRT deflection is generally used in 'scope applications where the vertical gain and the timebase are varied over quite a range whilst in use. In an electrostatic CRT you'l usually have five more electrodes than a magnetic CRT, two pins (electrodes) for horizontal deflection, two more for vertical deflection and one more for focus. That's very general, but generally true. There are a few odd CRTs that were deflected horizontally with an external coil, but vertically with plates - but they are oddballs and rare (thankfully).

The advantage for low-speed applications (NBTV/SSTV) is the amount of power required for deflection and focus is almost insignificant. The downside is the voltages required can be as much as 500V, usually less though for most common electrostatic CRTs, say 300V.

If this were your first foray into CRTs try to find a smaller (say 3") tube, the 3" DG7-32 is still widely available in Europe and not that expensive and easy to drive - getting the socket for it can be a different matter - but there are ways around that.

Steve A.

Postscript:- Attached is a PDF of a display I did 10 years ago using a DG7-32. I think it appeared in the NBTVA newsletter around that time but I'm not sure. Today I might do it in a different manner but as you can see it worked as described.

I've posted this before, so I apologise to those that have already seen it...

That took 30 minutes to upload for such a small file...rebooted PC and modem...no idea why


I think Steve the problem here is how do you start ! as in some one who has never touched one i am sure when you think back you had to work out how to experiment with one .
The good thing on the Russian tube he has is he has data but the voltages from a mains transformer still a bit of a worry but you have to want to be careful or you should stay clear of these .
The Magnetic CRT he doesn't and more than likely never will and would need some reverse engineering ,the one he wants to use is in a tv at the moment which i think still works so has a heads up if he can study and take some measurements study the tubes pin connects to what inside the tube ..
The problem he does have on both is he needs to be able the measure the High voltages which would kill hes meter without the HV probe..
Need a procedure depending on what he chooses as in doing this in steps study the tube mount the tube safely for experimentation power supply for the heater so on ,
Your Anderson circuit has been made twice by me and once buy Troy be a good one i should think if he gets to the stage of wanting to make one .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: XY Monitor / Display

Postby FlyMario » Thu Aug 16, 2018 2:25 am

Yeah it is more about a 16 dollar b/w tv that works having all of the power circuits. In my mind, I can cut the v and h coils and begin developing a good circuit to drive the electron beam in a pattern necessary for NBTV. I think in this case I can avoid all effort in trying to drive the tube itself. It would seem that whatever I do for the TV tube would be somewhat applicable to the Russian tube which is my end goal. Sure there would be different power requirements. That information might not even remotely scale.

I guess I could have just used my Tektronix 2246 instead of buying the little TV. That would have been more practical. LOL. In a bit of a daydream mode.

I do get completely scared of the high voltages. I find myself being very Absent minded. For instance, I can be soldering something, sit down at my desk... stand up and can't find my solder. For some reason, I put it on my desk. Afraid what I might grab that might knock the hell out of me.
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Re: XY Monitor / Display

Postby FlyMario » Thu Aug 16, 2018 2:37 am

Oh wow Steve! What a nice tube. Do you have any more pictures of your build? It is like NBTV porn!
FlyMario
 

Re: XY Monitor / Display

Postby Harry Dalek » Thu Aug 16, 2018 11:30 am

FlyMario wrote:Yeah it is more about a 16 dollar b/w tv that works having all of the power circuits. In my mind, I can cut the v and h coils and begin developing a good circuit to drive the electron beam in a pattern necessary for NBTV. I think in this case I can avoid all effort in trying to drive the tube itself. It would seem that whatever I do for the TV tube would be somewhat applicable to the Russian tube which is my end goal. Sure there would be different power requirements. That information might not even remotely scale.

I guess I could have just used my Tektronix 2246 instead of buying the little TV. That would have been more practical. LOL. In a bit of a daydream mode.

I do get completely scared of the high voltages. I find myself being very Absent minded. For instance, I can be soldering something, sit down at my desk... stand up and can't find my solder. For some reason, I put it on my desk. Afraid what I might grab that might knock the hell out of me.


HI you should be scared of the high voltages as it is what will make you think not to touch any thing !
like what i do and i am sure every one else say you now have your HV power supply you put a load resistor across it, when the power supply is on you know its a no goer to touch measure it ...but when turned off the load resistor slowly gets rid of the capacitor's voltage slowly shorting the charged capacitor..... higher the resistance longer it takes .....so you do in both cases check the voltage so you know its safe before you touch any thing .....
The load resistor can not be to low either as it will heat up when power supply is turned on 100k 200k something like that it will drop the voltage a touch while on a bit i use it to adjust the output voltage to whats wanted higher wattage resistor too 1M will not effect the voltage much but least it will bleeding the voltage away when power is turned off in time....any case you might be reminded if you get to this point


i feel the magnetic one would be a easier in some ways you can drive the anode via a bug zapper 7kv i think mine was 5 volts or under in i think positive 7kv out it should be variable unless you can measure it on the working tv .

A scope tv is a good first step too with out worrying about powering a crt ...Steves DAC is a good circuit to make a raster used it 3 times 2 in a camera ideas and in a magnetic tv this will be the 4th time on the FSC tv still need a deflection circuit if making a tv from scratch but for a scope tv just the DAC and low voltage circuits...
Last edited by Harry Dalek on Thu Aug 16, 2018 11:44 am, edited 1 time in total.
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Re: XY Monitor / Display

Postby FlyMario » Thu Aug 16, 2018 11:40 am

oh wait. Are you saying it takes 7kv to deflect the electron beam? Lordy.
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Re: XY Monitor / Display

Postby Harry Dalek » Thu Aug 16, 2018 12:57 pm

FlyMario wrote:oh wait. Are you saying it takes 7kv to deflect the electron beam? Lordy.


No just the positive to the anode its around there i used a bug zapper for the slow scan tv and the last nbtv one ...i liked it is smaller than a eht flyback transformer very cheap to...all the way from china again !
viewtopic.php?f=19&t=2080

viewforum.php?f=19

its that black box top left hand powered via a lm317 varying then the EHT to the tube this was the nbtv monitor
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Re: XY Monitor / Display

Postby Steve Anderson » Thu Aug 16, 2018 4:16 pm

Getting high voltages for CRTs can be a headache. Of the smaller CRTs the reason I suggest the DG7-32 is that its requirements are quite easy to fulfill. Find an old valve/tube radio that isn't worth restoring and pull its heart out - the mains transformer. But a lot had no transformer, they were powered directly from the raw mains and quite simply dangerous - but those were the days! That's mostly true in Europe where the mains is 220/240V, much less so in the US or countries that use 110/120V.

These transformers for yer average radio would have a high-voltage secondary of around 240-0-240V, ignore the centre-tap and you have 480V (RMS). Bridge rectify this into a capacitor and you'll have around 680V - probably somewhat more with no load, a CRT of the type we're talking about here uses far less power than a radio.

The transformer will also have at least one winding of (usually) 6.3V for the valve/tube heaters - use that solely for the CRT heater.

At the time I did the display above (the pdf) I had no 'proper' HT transformer, so as you'll note I used two standard transformers back-to-back. One advantage is the intermediate windings can be used for the low-voltage DC supplies. Even if you can find a donor valve/tube transformer you're going to need a second (different) transformer for the low-voltage stuff anyway - six of one, half a dozen of the other.

The first thing is to find the CRT, the rest of the design hinges on this entirely. There's no point in doing anything until you have it in your hands. Wherever you get the CRT from check the heater isn't open circuit with a multimeter. It will (should) be a quite a low value. A heater that is rated at 6.3V at 600mA has a resistance of 10.5 Ohms - when hot, when cold maybe 2-5 Ohms. As long as it's not open-circuit your chances are good.

Steve A.
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Re: XY Monitor / Display

Postby Andrew Davie » Thu Aug 16, 2018 4:35 pm

Just a reminder I have a small collection of CRT tubes basically just for the cost of post and pack.
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Re: XY Monitor / Display

Postby Steve Anderson » Thu Aug 16, 2018 5:06 pm

Andrew, yes I recall, can you list again or point to the pertinent posting? Cheers.

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Re: XY Monitor / Display

Postby Harry Dalek » Thu Aug 16, 2018 6:33 pm

Andrew Davie wrote:Just a reminder I have a small collection of CRT tubes basically just for the cost of post and pack.


Australia post has this service Andrew but they wack a 9 or 13 buck fee on it

https://auspost.com.au/business/ecommer ... n-delivery
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: XY Monitor / Display

Postby FlyMario » Tue Aug 21, 2018 9:22 pm

I am very happy to announce my Russian tube is here!
RussianTube.jpg
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Its the round thing without hair.

Hope I don't get accused of colluding with Russia over it!

It's so pretty! Must ... put... it ... back. Have too much stuff to do for Halloween props and my mechanical tv.

Puzzled though, why there is no nipple on top for a flyback (?). I see no place where that would connect.

Anyways... its so cool looking. It must not become a clock face... no... stop thinking about that Pete. NBTV instead.
FlyMario
 

Re: XY Monitor / Display

Postby Harry Dalek » Tue Aug 21, 2018 10:19 pm

FlyMario wrote:I am very happy to announce my Russian tube is here!


Always good when a crt makes it via the post !

Hope I don't get accused of colluding with Russia over it!


They pretty much did their own thing with valves and crts and such ,wonder if they were just copies of western Tubes so they didn't have to reinvent the wheel as such .

It's so pretty! Must ... put... it ... back. Have too much stuff to do for Halloween props and my mechanical tv.


Yes its best keep it safe till you have till to work on it

Puzzled though, why there is no nipple on top for a flyback (?). I see no place where that would connect.


Most of the time electrostatic tubes the Anode is via the plug have a look at the Data i linked in one of my past posts ...you need to Study the Tube what go's where via that plug ... its normal voltage operating range and maximum limits ....that's some thing you can do in the mean time know your friend !

Anyways... its so cool looking. It must not become a clock face... no... stop thinking about that Pete. NBTV instead.

[/quote]

No not a clock but i saw it has been made into one not something you want but even here data is of use how its powered

A first step as Steve mentioned is get your multmeter out check the data where the heater pins are and see if you get a resistance reading and your heater should work if it were powered and its worth using ..
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: XY Monitor / Display

Postby FlyMario » Sat Aug 25, 2018 7:01 am

So I found a web page that would let me "translate to english" the specifications for my Russian tube. The site is http://zapadpribor.com/5lo38i/

TubeEnglish1.jpg


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Here is yet another page ... http://www.cfp-radio.com/realisations/r ... es-01.html
It can be translated as well so that is nice.

It has the tube pinout. Some words on it are obvious and others not. The X and Y's must be where you aim the beam. Let me guess that heizung is the heater since I know that the heater takes 6.33v. Pin 4 and 10 must be to focus... Oh god... are the anode and cathode holding 1000v. wow. I think I read somewhere there is a min and max... Sometimes the specs seem to contradict each other.

Focus takes 138v to 300v? now I am confused. Pin 10 must not have anything to do with focus. whatever 10 is needs -30v to -90v .

So now I see that 10 must be brightness. puzzled by that voltage.

CRT tubes sure love different voltages. It says 6.3vac... why? A heater doesn't mind dc right? Isn't that just a element that heats up the tube?

This is going to be so much fun. Hope I am not too annoying.

Pete
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Re: XY Monitor / Display

Postby FlyMario » Sat Aug 25, 2018 7:30 am

I measured ohms between what I suspect is the heater and I get back 9.2ohms.
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