The Thylacine a monitor in construction

[dalekmoore2007]

Here's a a monitor i am constructing i want it to run in the low hundreds of lines .
I want it to be multi system frame rates are 6 hz 12.5 hz 25hz 50 hz 100 hz
line rates up to low hundreds i really want it around 100 to 200 or so lines for now but i will see how it goes once finished ,i really have only done a modulating test freeing running no syncing on 32 lines before i made up my mind to case it and next time i try i should be able to do better .
History of the monitor here to date
http://www.taswegian.com/NBTV/forum/...hp?f=10&t=2432
http://www.taswegian.com/NBTV/forum/...hp?f=15&t=2436
the projects that put me on the road to the Thylacine
http://www.taswegian.com/NBTV/forum/viewforum.php?f=31

[Panrock]

Good to see you here Harry!

dalekmoore2007 happens to be one of the world's most prolific NBTV'ers. He's in Australia so sadly won't be coming to the Saturday 7th April NBTV Convention here in the UK. But if you'd like details, PM me.

Steve

[Radio Wrangler]

It would be rather amusing to feed it a video recording of a tape cassette with its spools slowly rotating.... shades of those artificial log fires now in all the DIY sheds.

David

[dalekmoore2007]

Originally Posted by Panrock

Good to see you here Harry!

dalekmoore2007 happens to be one of the world's most prolific NBTV'ers. He's in Australia so sadly won't be coming to the Saturday 7th April NBTV Convention here in the UK. But if you'd like details, PM me.

Steve

Hi Steve i knew you were here as i reading some Argus posts a while back,always my inspiration on a CRT television builds .
I think magnetic CRT's are so much harder to tame than a electrostatic tube this has taken me so far many months just to get this far .
Yes it is a pity the convention is so far away but any one in the uk you should go .
There's something nice about making or trying to make some thing work that does not have to be state of the art ,there's no fun just buying stuff all the time ....no one in time will know any thing about making their own gear .
I like electronics pretty much like 60s 70s so lack of ever getting a magnetic crt to work this has to change !
i need it really as a display the only thing that will feeding it from my multi system pmt camera and the also vidicon multi system camera i am working on .
i can also out put the signals from the monitor to a scope so it can do what perhaps this monitor can't .

[Argus25]

Originally Posted by dalekmoore2007

I want it to be multi system frame rates are 6 hz 12.5 hz 25hz 50 hz 100 hz
line rates up to low hundreds i really want it around 100 to 200 or so lines

The rate that the current changes with time in the frame deflection coils depends on the drive waveform to those coils from the amplifier driving them. So for those it is relatively easy to create a 6, 12,5,25,50 100Hz frame scan provided the low frequency response is adequate (coupling capacitor) to the yoke if present, is large enough and the drive voltages to the output amplifier have the correct amplitude, shape and frequency.

It is a whole other story for the line deflection coils.

( Firstly if they are disconnected from the existing line output stage it might in some cases be necessary to replace then with an inductor to maintain the correct EHT for the CRT).

But under normal circumstances the current in the line coils is not determined by the drive voltage shape (which is rectangular), but by the rate of rise of current with time due to the applied voltage to the line coil inductance, which is V/L as it turns out.

So if you need a variable line rate scan. One possible method would require instead a current controlled drive to these coils and to drive them with an output amplifier which is a controlled current source. This can be done by placing a small current sense resistor in series with the coils and putting that into a feedback loop with an OP amp to drive the new power output amplifier to these coils during scan time. Otherwise it might be difficult to control the line linearity.

One other method that could work is to control the applied power supply voltage to the line coil's circuit during about 2/3 of the scan and keep the energy recovery diode on the line coil circuit (the initial third scanned by damped current in the usual way) and simply vary the applied supply voltage for each line rate setting, so that the proportion of V/L is correct to get the correct scan amplitude. It requires a variable power supply with a low Z output or the linearity will suffer. This method though will give the better results for flyback- a brisk flyback of the scan, which would be more difficult with the first method.

Hugo

[dalekmoore2007]

Hi Hugo thanks for the advice i will study what you have said ! Yes lots of problems making a multi system monitor ,it has its own EHT unit so it has nothing to do with the horizontal i wanted that problem out of the way from the start ! .
Today i hooked up my video board for some control grid modulation ...no syncing yet .
https://www.youtube.com/watch?v=YyP0...ature=youtu.be
here are some 32 and 64 line tests
pictures all 32 line i am a NBTVer !