Hi Steve,
Steve Anderson wrote:Hi Steve, long time no contact, I guess we've both been busy one way or another...
Yes, it's nice for me to once again have a little time available for NBTV... though this project won't be quite so "NB" as usual, this time...
Steve Anderson wrote:I agree with your 240kHz bandwidth requirement calculation for this, thus if using a similar PWM system you'll be looking at switching in the low MHz region. This may become 'Not so easy', but let me dwell on it for a day or two...
Thanks! I'll be building this from the ground up and not re-using any parts from the old system, which is now gathering dust and taking up a fair bit of space in the store room.
Steve Anderson wrote:Those 2N3055s/MJE3055s will definitely have to go!!
Thought that would be the verdict. I recall you weren't too keen on them before either, but they were 'legacy' parts on my rig and you allowed me to retain them.
As for the new 'line of light', I wonder what driver transistors you will recommend? I'll need to go all out here for maximum power and a fair number of luxeons, since (as I think Karen O mentioned) at 120 lines picture brilliance (or rather the lack of it) could become a problem. I'm hoping though that things will be helped here by the sheer size of this mirror screw.
I'm thinking of building this line of light around a vertical perspex rod with one side flattened and frosted. The lines of luxeons would be housed inside a vertical 'wedge' with reflecting internal surfaces, and they would be beamed onto the inward facing flat frosted surface of the rod for colour mixing.
Steve Anderson wrote:In thinking about this, what's going to be the source of video? Does (for example) the 'Aurora' standards converter provide this? And do you have one? Or do you have something else in mind?
I have been thinking it would be worth my while investing in one of Darryl's 'World Converters'. This could certainly provide the RGB 120-line video (amongst many other standards). However, I have also received a couple of kind offers. Dominic Beesley has offered to provide software that outputs from my sound card (not sure if this could be colour though) and Jeffrey Borinsky has offered to lend me his own World Converter.
Steve Anderson wrote:This definitely does interest me (and Jeremy Jago via previous e-mails) though I will admit I'd take the easy cop-out and use a CRT...of course monochrome in my case, but if there's a requirement for a signal source at these standards, then I'm interested...
Speaking personally, I got the CRT urges out of my system by building the 405-line
'Argus'!
But It seems to me that if one wants a
mechanical display that can also produce a visually large, relatively high definition, colour picture - the curved-face mirror screw is the only realistic option. Once it's built and working, I'd like to see if it holds any potential for 3D too... though the answer is 'probably not'.
Steve Anderson wrote:to wit, I'm in the process of trying to pull together an item for the newsletter, not the one usually due this month, but the December issue. If Jeremy decides to publish it, here's a sneak preview...
it has 16 Club Standard test patterns encoded within it, in fact 32, 16 being linear and 16 being Gamma-encoded. Once I'm finished with the last of the software it's done...a few more hours of work....there's more to it, but my reason for mentioning it here is if there's no source for your 120/25p video I'm willing to uprate it to suit....colour might be interesting (read a challenge) though...
Wow! This would be great if you could crack it. I can envisage needing a sharp-edged waveform when I'm finally 'tapping' the slats to (try to) remove any remaining jaggedness from the picture. I'll probably just feed in a fast square wave...
Steve O