NBTV without any moving parts. THE NIPTRIX

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NBTV without any moving parts. THE NIPTRIX

Postby rommert » Mon Dec 10, 2012 12:00 am

Good day Albert.
Indeed it looks familiar to me.
Because i have soldered the leds diagonaly on the veroboards as explained
before, i could not use veroboard with continuous tracks, but had to solder
crossing wires, instead of using continuous tracks as you do.
I also left the leads from the leds as long as posible as you did.
The other sides i shorted a little to be able to solder the crossing wires.
I isolated each row (and column)by a double folded piece of paper.
On your picture i see you started by soldering one lead from each led first. I did the same. This gives the opportunity to align each row before soldering the other leads.
To leave the leads as long as possible gives the possibility to bend away ( temporarely )
a completed row before soldering the next row.
I am very interested in your project. Especialy in the behaviour of the white leds in contrary with mine overdriven red leds.
Kind regards,
Rommert.
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Postby Viewmaster » Mon Dec 10, 2012 12:01 am

gary wrote:Nice work Albert, good luck with the rest.

The straw sections are not glued on right?

The only reason I ask is that when you first mention the "interference" between adjacent LEDS I thought hmmm well yeah. But now I wonder whether that would be a minus or a plus. The fact that adjacent LEDs would "glow" in sympathy with the "powered" LED might give a pleasant "softening" to the picture. Thoughts?


No, the straws are not glued, just a good push fit and you raise an interesting point.
You may recall that Rommert originally drew my attention to light leakage as though it had a negative effect and was something to be avoided. Hence my straw idea........
.....maybe I am just, " clutching at straws in the wind." :lol:

As my straws are not glued in I can remove some to see if your idea of 'glowing in sympathy' looks to have merit.
If so, would anyone wish to buy about 800 black party straws about 1/4 " long? :shock:

I am also going to put in a facility to switch over from full sync to a couple of 555's running , freq.controlled by 2 pots. In this way I can see all sorts of effects as pots are adjusted up and down and on very slow scan can see if any LED needs changing.

It's quite interesting assembling a TV picture together pixel by pixel, as long as it's not 405 lines !!
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Re: NBTV without any moving parts. THE NIPTRIX

Postby Viewmaster » Mon Dec 10, 2012 12:14 am

rommert wrote:Indeed it looks familiar to me.

Especialy in the behaviour of the white leds in contrary with mine overdriven red leds.
Kind regards,
Rommert.


Hello Rommert,
I sent my previous letter before reading yours, which arrived within a minute or so.
The biggest problem with non diffused LED which I am using, is, as you will know, the rather narrow light beam one gets before rapid fall off in light output. So one will have to be rather central to get the full picture.
I believe your LEDs are the diffused type so one has a wider angle to view.

I wonder if you read Gary's comment about allowing adjacent LEDs to 'glow in sympathy' without any masking between them?
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Postby AncientBrit » Mon Dec 10, 2012 11:47 pm

Gary,

re deliberate optical crosstalk, a bit like the 2D filters you discused with me a few years ago when you gave me a very quick tutorial on types of LPF used in sampling.

Cheers,

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Postby gary » Tue Dec 11, 2012 10:16 am

AncientBrit wrote:Gary,

re deliberate optical crosstalk, a bit like the 2D filters you discused with me a few years ago when you gave me a very quick tutorial on types of LPF used in sampling.

Cheers,

Graham


Yes Graham, it is an anti-alias filter with unknown parameters - the question being - is it a force for good or a force for evil? ;-)

In other words do we describe it in negative terms like "cross talk" or "interference" or positive terms like "averaging" or "smoothing"? ;-)

My gut feeling is that a LED matrix such as this, with relatively large spatial distances between pixels, could do with some smoothing - but maybe not. I just thought removeable barriers allows one to test it empirically.
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anti-aliasing.thumbnail.png
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Postby Viewmaster » Tue Dec 11, 2012 7:20 pm

gary wrote:My gut feeling is that a LED matrix such as this, with relatively large spatial distances between pixels, could do with some smoothing - but maybe not. I just thought removeable barriers allows one to test it empirically.


Possibly there should still be barrier between the 32 lines but maybe not between vertical pixels, as a side bleed of light between the 32 lines would not correlate at all to a spinning Nipkow display but a vertical bleed would.

BTW, 9 rows of LEDs now completed as you can see, without any hassle so far. At this rate will be finished about mid Jan.........well I must have a break to eat my Turkey :)
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Picture2 335.jpg
soldered side
Picture2 335.jpg (150.85 KiB) Viewed 8234 times
Picture2 333.jpg
288 LEDs marching along
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Postby gary » Tue Dec 11, 2012 7:59 pm

Actually, looking at that there may not be as much of a separation as I thought. I think in my mind's eye I was thinking of Grant's version. I *think* he used LED matrix modules which *seem* to have a larger separation than is possible when individually position by hand.

I don't think 48 pixels is enough to warrant NOT having smoothing along the scan line.
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Postby Panrock » Wed Dec 12, 2012 8:16 am

Very nice so far Albert. Well done!

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Postby AncientBrit » Wed Dec 12, 2012 6:48 pm

@Albert, Nice piece of engineering

@Gary, re smoothing/filtering, how about a sheet of diffuser in front of the assembly?

Cheers,

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Postby gary » Wed Dec 12, 2012 6:53 pm

Graham, I was going to suggest that myself right at the start but dropped the idea when we started talking about the LEDs being over driven because otherwise they are not bright enough - I didn't want to suggest something that would probably make the conditions even worse.

I am sure when Albert gets it going though it may well be something he considers trying.
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Postby Viewmaster » Wed Dec 12, 2012 7:05 pm

Graham, I have tried putting a piece of the club's diffuser material in
front of and touching an LED but there is too much side illumination, and anyway, the light o/p goes right down, something I wish to avoid as I do wish for the brightest display.

Maybe the best solution would be to put 48 blocking diodes and 48 Rs
between each of the 48 rails to the LED pixel rows. In this way when a LED is on the PREVIOUS one is also partially on too depending on experimental value of the R. That seems very close to simulating a Nipkow disk.
That isn't too much additional work and easily done......When all finished might try that on just a few of the 48 lines.
Last edited by Viewmaster on Wed Dec 12, 2012 7:11 pm, edited 3 times in total.
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Postby AncientBrit » Wed Dec 12, 2012 7:07 pm

@Albert,

A kind of controlled crosstalk. Worth a try,

Cheers,

Graham
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Postby Viewmaster » Mon Dec 17, 2012 7:01 pm

Half way there. :shock:
Gosh, The Niptrix is sure using up a load of solder.
I find that the soldering is very easy though, although it doesn't look that way.
The very worst job is removing the bottom flange on the LEDs at four places so they can fit together. Very tedious.

I shall now have a break and a drinkies.....non alchoholic of course :)
Attachments
Picture2 340.jpg
Solder, solder, solder
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Picture2 339.jpg
Half way.
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Postby Steve Anderson » Mon Dec 17, 2012 7:57 pm

Yes, you will eat up a lot of solder, you'll also notice that the board will start to increase weight as you progress...

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Postby Viewmaster » Sat Dec 22, 2012 12:10 am

Have you seen the google logo today, Steve?
End of the Mayan calendar....... as far off topic as one might wish for.
And this photo is Google's copyright so as it's Xmas let em stick that in their cracker and pull it. :lol:

Thailand may have disappeared but the ol' UK is still knocking around here so far.
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