32/60 LINE NBTV TELEVISOR

[Harry Dalek]

Peter Spies using pretty much the Anderson monitor circuits soon as i saw him adjusting the sync i knew what the circuits were without looking at the description.
Some great television projects by Peter https://www.youtube.com/@peterspies610


youtu.be/XU3ogVn1plM

[Steve Anderson]

Nice to see some credit! Though nothing in that original is 'rocket science!' I might consider something similar to the late Chris Lewis's "Rate Convertor", i.e. 12.5Hz to 50Hz to eliminate the frame-rate flicker, though the 'picture update' (for want of a better expression) would still be at 12.5Hz. Chris's version could be vastly simplified today, it was published in the NBTVA newsletter some years ago...I'll dig out which issue it appeared in.

This has been on my 'To Do' list a long time now. There are two possible variants...

1) Standard NBTV of 32 lines simply at four times the frame rate.

2) Standard 625 with the NBTV video embedded.

I think the second option is more desirable? Not sure, comments please. The second option will be slightly more complex, but not overly so, not too complex for anyone who can build a 'native rate' NBTV monitor anyway. Though we'll see on that as it develops...ideas and concepts brewing already....in fact I did some initial work on this a few years ago...time to dig it out...

As for the 60Hz source variant, not so sure about that. Though a 625/50 to 32/12.5Hz variant is certainly feasible. The hardest part is going to be the 625 A-D, even today the choices are limited for those doing home construction...

Steve A.

[Harry Dalek]

Yes i thought you would like to see this one i am sure its nice to know the circuits do get used apart from me !
I don't think any ones to bothered what you would choice to do any thing that works is wonderful if any one else thinks like me if it works its worth making !

[Klaas Robers]

I prefer the NBTV to 625/25 version. I have two CCIR monitors, so display is not difficult.

I think my 25-line Nipkow disc will not speed up to 50 rev/sec.

Would it also be possible to make a scan-converter of 32/12.5 to 32/variable? My Nipkow disc may give a single syncpulse per revolution. If the output "video" syncs to that pulse, I don't need a disc synchronisation, it might run somewhere between 25 rev/sec and 50 rev/sec and will always give a stable picture. May be I can speed it up to 37.5 rev/sec...... At least I can experiment with the enoyance of the flicker.

[acl]

Hi there all,

I think you were referring to Graham Lewis and not me. I have revived Grahams NBTV 32 to VGA convertor and it works well. Here is the circuit for Karen's to be found in newsletter Vol 43-2 I thought of producing a PCB for it and should 625 monitors go out of fashion use a 625 of VGA converter. This worked well on my SSTV monitor.

[Steve Anderson]

.....I think you were referring to Graham Lewis and not me.

Ooops! You are correct. I didn't intend to send you to an early demise!

I'm still playing around with VGA monitors as a display option as it won't be that long before analogue inputs on TVs vanish though many will still be in service for another decade or so. We bought a new TV about a year ago, the only analogue video input it has is VGA. Or RF/antenna, unused, no analogue RF TV here now.

We do have terrestrial digital TV but the uptake has been so small that's under threat of an early extinction. The vast majority of TV sinals are delivered either via satellite, cable or fibre.

DAB has been rumoured in the past, but I think it won't happen. New cars are still fitted with FM-only radios, Japanese version, 76-108MHz, no AM or DAB. Most AM stations have closed down out of choice (no listeners), not legislation. There used to be an AM transmitter on around 700kHz, 2kW, 2km south of here, often 'broke in' to analogue stuff I built, thankfully gone now.

Steve A.

Although the FM radios can receive down to 76MHz, there are no stations below 88MHz. So why are they fitted? Good question!