Making the smallest Nipkow NBTV, THE NIPKOW NIPPER.

Forum for discussion of narrow-bandwidth mechanical television

Moderators: Steve Anderson, Dave Moll, Andrew Davie

Postby Viewmaster » Fri Nov 25, 2011 6:31 pm

The smallest Nipkow disk NBTV that I am building now has a name....
THE NIPKOW NIPPER :-)
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1289
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

Postby gary » Fri Nov 25, 2011 6:49 pm

Viewmaster wrote:The smallest Nipkow disk NBTV that I am building now has a name....
THE NIPKOW NIPPER :-)


...and it hasn't even been born yet! Can't wait for the Christening... ;-)
Perfecting an NBTV system is like trying to slam a revolving door...
User avatar
gary
"Fester! Don't do that to 'Thing'"
 
Posts: 2303
Joined: Sat Jan 27, 2007 11:29 am
Location: Bundanoon, Australia

Postby Viewmaster » Fri Nov 25, 2011 7:24 pm

gary wrote:
Viewmaster wrote:The smallest Nipkow disk NBTV that I am building now has a name....
THE NIPKOW NIPPER :-)


...and it hasn't even been born yet! Can't wait for the Christening... ;-)


Let's hope that it isn't stillborn, Gary :-) ...........

........ I bet that 4046pll midwife will be playing up again as the mechanics have non standard 12 inch Nipkow NBTV attributes.
If so, I may have to give it a Caesarean section ;-)
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1289
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

Postby Viewmaster » Sun Nov 27, 2011 10:30 pm

For those following this, here is an update..........
Here are 2 photos of THE NIPKOW NIPPER.
As I cannot do any trials re Dome light sensor/illuminants until I have the means to rotate the 2" dia film at 750 RPM I have stormed ahead with the mechanics as you see.
You can see a piece of loose film where the 2 perspex washers will hold the final film image. On the right is the adjusting part to move the film bewteen the perspex washers to get scan hole alignment under high magnification.

The mini video camara is the black thingy with a black wire coming out.
The white tube in front of it is the extension tube for the camera's lens.

You will see that the camera is on opposite side to where the NBTV picture is normally viewed. I intend to have normal viewing on the right hand side....for those with good eyesight ! :-)

On the left the inverted image will be seen by an inverted camera.

The .004 inch dia holes show up well on the first 120 film I shot BUT although I took 12 photos of disk with various exposure/apertures to get the best, the focus is slightly out so I am going to retake at various focus sittings.

The old Ensign Selfix has no means of accurate focus at close ups so I am
focusing on a home made frosted glass screen where the 120 film runs.
Camera lens is only f4 so I had to blast lighting onto the trial tapering focusing steps........45 degree upward slope with lines every 1/4 inch
to see plus/minus distances for focusing.

More updates, probaly after Xmas now...........have a happy one, BTW.
Attachments
NIPKOW NIPPER.jpg
THE NIPKOW NIPPER
NIPKOW NIPPER.jpg (45.37 KiB) Viewed 6452 times
Scanning head.jpg
Scanning head
Scanning head.jpg (53.6 KiB) Viewed 6452 times
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1289
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

Postby Viewmaster » Thu Dec 01, 2011 1:06 am

Just a quick update for those mad enough to go the Nipper way. :-)

New film back now from processors OK.

Idea this morning.........
To get maximum contrast with minimum light leakage through the black parts of the film I am going to sandwich the correctly exposed good filmed image, being used for scanning, with a very dark underexposed film image.

The under ex will have the scanning holes drilled/punched right through the film about .03 inch dia. (good scan holes are .004 dia)

So the smaller scan hole images will 'look through' the oversized holes
in the under ex..
Registration will not be too critical because of the oversize, as long as the good scan holes are being shown every 32 positions.

I have tried this drilling with a tiny drill by hand on film and providing one starts the hole by marking its position with a needle indent all is OK.

Have made a small light box to see what the hell I am doing. :-)

So light leakage through the good image film will only be around a small area instead of from the full top to botton scan. This should greatly reduce the background light leakage and increase the contrast.
More anon.............
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1289
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

Postby Viewmaster » Mon Dec 05, 2011 12:14 am

Here's a piccy of the resultant mask, stuck on my window, with the oversized masking holes (.020 inch dia) prevoiously mentioned clearly shown. This mask is an underexposed version of the true mask to be used on the Nipper, to get as much blackness between scan holes as possible.

Holes are not yet cleaned up here and there of drill swarf but holes are in position to allow the main .004 dia scan holes on the other filmed image to shine through.

You can also see the sync hole images too, but these will not be used on this mask, only those on the correctly exposed main image film.

Some few thou possional errors are permissable as the sketch illustrates,
as long as the main scanning hole images shine through the mask.

Have also dug out an old 741 circuit which is a sensitive adjustable volt detector and this gives a big pulse out from the club's camera domed light piece, even on very small light present.
So sync from the tiny film sync hole images now seems possible to get, as a true copy of the Nipkow's bigger brothers.
Attachments
Scan and masking holes.JPG
Mask hole errors
Scan and masking holes.JPG (18.95 KiB) Viewed 6366 times
Mask.jpg
Masking film
Mask.jpg (35.47 KiB) Viewed 6366 times
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1289
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

Postby holtzman » Wed Dec 07, 2011 7:37 am

I am gelous :!: Can't wait to see it working!
holtzman
Just nod and pretend you understand me
 
Posts: 215
Joined: Wed Apr 22, 2009 7:54 pm
Location: Jerusalem, Israel

Postby Viewmaster » Wed Dec 14, 2011 8:14 pm

Still making progress, although the control board is not yet built. (will go in the black box at the Nipper's base.

Latest picture of the head.
Just realised that if I wish to show a tiny NBTV picture on the normal right hand position and the inverted mini camera on the left I need to have 48 scan holes so 16 more mini drilling holes to be put on the mask. Fortunately as the film is a direct copy of the club's 48 hole Nipkow disk, the extra 16 images on film are already there.

I have never used luxeons before so thought this a good time to start as I need tons of light. Gee aren't they something ! Blindingly white.

The club's domed light detector is mounted in a black enclosure, to prevent unwanted light, with just a tiny hole for it to 'look' at the filmed image sync holes, illuminated with an LED.

The system has nil inertia and stops running as soon as power is removed from the motor, so I foresee some problems with the pll. A small flywheel maybe added.

All this Nipper design is an unproven way to go, but 'Modification' is my middle name. :-)
Attachments
Nipper's head parts.JPG
The Nipper's head.
Nipper's head parts.JPG (67 KiB) Viewed 6267 times
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1289
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

Postby kareno » Mon Jan 09, 2012 11:14 pm

My experience suggests that your observation that the disk stops almost immediately on power removal is a very good omen indeed Albert - I would NOT add any additional mass!

As well as my own observation, there is good mathematical reason for believing the lower mass situation is better - the time constant for motor speed change (as a result of a change in supply voltage) translates directly to damping when the inherent integral action of the speed-phase relationship is added into the transfer function, and a feedback loop closed around it.

Case in point with my OHP disk - I fixed the transparencies to a transparent plastic disk for rigidity. This made the system very difficult to control. My observation about stopping time was reaffirmed - this disk takes 38 seconds to stop on power removal!!!

I plan to revisit my OHP monitor soon and try another approach to making the OHP disk more rigid.
kareno
 

Postby Viewmaster » Mon Jan 09, 2012 11:36 pm

kareno wrote:My experience suggests that your observation that the disk stops almost immediately on power removal is a very good omen indeed Albert - I would NOT add any additional mass!


Now that is interesting as, for me, it only adds to the 4046's mysteries.

I have quite a large rotating mass (large by NBTV standards) on another project of mine, still being slowly progressed (The Edikow machine).

A very large DC motor being used and other mass in the system takes about 3 seconds to come to rest from 3000 RPM when turned off.

The club's 4046 pll circuit is used for project speed control and when turned on, (using no missing frame pulse), it locks into sync within about 1 second from start up without any juggling with pots/switches or fingers being used as a brake.
It does lock firmly every time.

So it does show that stopping immediately is not required on all systems.

The interaction between the 4046 and the mechanics is such that maybe, sometimes, more inertia and slow down speed is required than at other times depending on many variables, even belt drive tensions etc.,
although in my system only a toothed belt is used so not too much tension there.
Also the motor's running speed may enter into this loop of mystery! :)
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1289
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

Postby Viewmaster » Mon Jan 23, 2012 10:54 pm

Just an update on Nipper's progress.........he'll soon be in Junior school ! :lol:

Now experimenting with the club's dome light sensor and LED lighting to get at least 5 milli V out. This will trip my volts detector and give me the sync pulses.
The dome is masked out with just a small hole 'looking' at the film's sync hole images. The LED is blacked all over except for a small window at its front 'looking' at the disc.

The 2 inch film imaged Nipkow is now sandwiched between perspex washers.
Just about 1/16 inch protrudes to allow me to align it up eventually.

Perspex can hold static charges so dust maybe a problem, partly blocking out the .004 dia Nipkow scanning hole images.
This is a new ball game I am in......maybe something else I might be in soon, if things go wrong !

Most of the circuitry is now built, the dry joints and shorted tracks in the vero board are being tested! :oops:
Attachments
LED and dome.jpg
Close up of dome and LED
LED and dome.jpg (46.02 KiB) Viewed 6084 times
Film  Disc.jpg
Disc, dome and LED
Film Disc.jpg (68.77 KiB) Viewed 6084 times
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1289
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

Postby kareno » Tue Jan 24, 2012 4:42 am

I have had a thought. Last summer I bought one of those kiddies microscopes from a car boot. It was attractive because it included a 'ground glass' screen alternative to the eye piece lens.

I wonder if one of these could be used with the Nipper? Only trouble is, you'd need a very bright light source indeed - the microscope uses a torch bulb (the sort with integral lens) for illumination when using the screen attachment.

I have visions of the disk melting like celluloid film if the motor stalls!
kareno
 

Postby Viewmaster » Tue Jan 24, 2012 8:16 pm

Karen, at present I am only using a non ultra bright LED for the sync detection, so could go to ultra or even a luxeon on low power if need be.

As you say any ground glass in the optics reduces light.

The sync hole images in the Nipkow film are about .012 inch dia
so I shouild be able to stimulate that dome light detector eventually,
without the vision of a melt down........
How about built in ' power off ' switch on zero revs :wink:

The other answer is to have a seperate sync wheel, but that would completely negate the original idea to have a tiny Nipkow which copies his bigger brothers in ALL respects.
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1289
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

Postby Viewmaster » Sun Jan 29, 2012 12:33 am

Latest update........
I am now experimenting with a different mini video camera for the Nipkow Nipper, that has 'sense up' built in, all adjustable from x2 up to x256 on the OSM.
The shutter speed is still 1/50 second but I have found that the picture refresh rate is lowered the more the sense up is increased.

With the 'sense up' set at maximum ( x256) the output picture only refreshes about 4 times a second, so motion is badly blurred. The sensitivity also rises sharply.

So hopefully a refresh rate in the region of 12 times per second or slightly less might remove those troublesome flickering bars from the NBTV picture, once I get Nipper running around !
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1289
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

Postby Viewmaster » Mon Feb 06, 2012 11:34 pm

"One small step for Nipper. One giant leap for syncing."

I have replaced the club's domed light detector. The .012 inch dia sync holes in the Nipper's filmed Nipkow only gave a very tiny output. I could have built the club's camera amplifier but the circuit is sensitive to bad layout etc. so decided not to spend time building it.

Instead I bought a cheap 3 pin light detector which has a built in amplifier.
This gives me a 1/2 volt swing in o/p as the sync hole images pass by.
This 1/2 v swing triggers my volt detector and so gives me the large pulse required for the 4046pll.

Another big step for the Nipper is that the film adjusting screw idea, with the oversized centre hole, in the film works well. Within a few minutes I had the disc adjusted to within about .002 inch of its correct position. So it will be easy to get it within tighter limits so that the scanning hole images 'spiral in' corectly. The big image of the sync holes on the LCD viewer is a great help in adjusting the sync images so that all 32 run round in a single line without radial wobbling. This means too that the scanning holes also are true.

Picture of new OSM video camera shows how close to the perspex washers
holding the film, the front of the lens is.
All adjustment is very critical for focus and out of squareness etc. but as everything has adjusting screws eventually correct alignment should be possible.

I now have to replace the motor for a larger one then I shall be able to play with all the many camera's OSM adjustments to try for some kind of picture. :shock:

I daresay the Nipper will need a smack or two........does the law allow for the smacking of Nippers these days? :lol:
Attachments
OSM video camera.jpg
OSM video camera
OSM video camera.jpg (65.82 KiB) Viewed 5928 times
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1289
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

PreviousNext

Return to Mechanical NBTV

Who is online

Users browsing this forum: No registered users and 4 guests