From Cats-whisker to Television.

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From Cats-whisker to Television.

Postby Steve Anderson » Thu Jun 14, 2007 12:33 pm

Ferreting through my files I came across this which I had forgotten about. Seeing it was published in 2000 some may have not seen it.

The file name ends in '3', so I presume there were two previous issues and perhaps further ones. This is the only one I have.

There's no mention of copyright or the (c) so I hope it's OK to post it. If not I'll delete it.

Steve A.
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Postby DrZarkov » Thu Jun 14, 2007 4:57 pm

Well, Peter is a club-member, and the circuit is in the NBTV-handbook (slightly modified), too. But an interesting story.

I wonder if a mirror-drum monitor is much more work than a nipkow-disc monitor. Looks good for a future project...
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Other ways of doing the same thing...

Postby Steve Anderson » Fri Jun 15, 2007 5:19 pm

DrZarkov wrote:I wonder if a mirror-drum monitor is much more work than a nipkow-disc monitor. Looks good for a future project...


There have been many incarnations of mechanical TV, Peter Yancers' site covers the majority of them...

http://www.televisionexperimenters.com/home.html

Steve A.
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Mirror drum alignment.

Postby Steve Anderson » Sun Jun 17, 2007 12:48 pm

DrZarkov wrote:I wonder if a mirror-drum monitor is much more work than a nipkow-disc monitor. Looks good for a future project...


As Peter says in the article, "...I could not put off the task of adjusting the mirrors. This took many hours and still the alignment is not 100%".

This is a tricky operation as each mirror is in a slightly diffferent position to its neighbour and needs to be correct in two axes.

There is an advantage though, each mirror (in theory) can be set exactly correct unlike a Nipkow disc where once a hole is drilled, that's it!

As a conceptual thought a laser pointer could be used as a reference beam aimed at each mirror in turn, having done some maths the reflection aimed at a template at some distance away and each mirror adjusted to its individual position.

If you look at the picture you can see the three screws and nuts used to adjust the mirrors in two axes.

Steve A.
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Postby DrZarkov » Sun Jun 17, 2007 3:01 pm

The laser pointer is a good idea, but why not just use a screen where the lines are marked? You can see exactly when the laserbeam is between the two marks of a line? It looks easier than for example a mirror-screw, where a wrong placed mirror can distroy the use of the whole screw.
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Postby Viewmaster » Sun Jun 17, 2007 6:58 pm

How about adjusting this 5 (!) channel TV receiver using a mirror drum?
Uses an arc with Kerr cells and 5 prisms.
No lasers to help in those days.

This has been taken from a chapter, "Multi channel TV," in the book, Television Today, volume 2, by the way.
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