Mechanical video recorder

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Re: Mechanical video recorder

Postby Harry Dalek » Thu Oct 10, 2019 7:12 pm

Below Cassette Tape recordings got the camera light levels a bit off to bright but much better results to nothing on the software monitor




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I also tried also grey bar reversing wav on the below recorder but only got poor results ,still have very low record levels for the stylus so that wouldn't help either need a bit more amplification just using the out put of the lap top to the stylus stepper motor here, the stair case looks more like a ramp waveform and no syncs at all ...More work

Yes Steve Speed would be more constant on a drum than a record but i am sure Albert would tell us using he's wax cylinder was pretty hard any case to record on ...Think from what i have noticed on the tape recording its more what Klaas mentioned its more important to get if possible all the video information on the thing you are recording on if possible speed is more a bit of sync problem .
How Baird did phonovision in the early 30s is amazing to me i am starting to see all the little problems but it does make it interesting to me .





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Re: Mechanical video recorder

Postby Steve Anderson » Thu Oct 10, 2019 7:43 pm

Harry Dalek wrote:I do have 2 reel to reel recorders which i saved from here and there but yet to Test them ! as i get older i seem to have more time to try things out ..so another on the to do list i think i might be lacking a empty reel for the odd tapes i have to wind onto ..have to see if i ended up finding one or not .


Harry, I have a few empty 7" take-up spools for 1/4" tape, also one 5.5". If you really get stuck finding one I'll mail one to you...all have the 3-pronged "cine" hub arrangement, (the usual domestic tape-spool arrangement), not NAB. See pic..

Steve A.
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Re: Mechanical video recorder

Postby Klaas Robers » Fri Oct 11, 2019 7:16 am

Wow Steve, you have a Philips tape spool. My heart opens....

No no, don't send it to me, I will have a few. But you know, Philips was, and is still, my company.
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Re: Mechanical video recorder

Postby Harry Dalek » Fri Oct 11, 2019 12:29 pm

Steve Anderson wrote:
Harry, I have a few empty 7" take-up spools for 1/4" tape, also one 5.5". If you really get stuck finding one I'll mail one to you...all have the 3-pronged "cine" hub arrangement, (the usual domestic tape-spool arrangement), not NAB. See pic..

Steve A.


Thank you Steve ! i will have a look today if i did end up finding one at some time ,if i am not using it there and then i tend to put them together and forget about it !
I will have a look in my shed today /
The reel to reel were once easy to find not so these days ..
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mechanical video recorder

Postby Harry Dalek » Fri Oct 11, 2019 12:31 pm

Steve Anderson wrote:
Harry, I have a few empty 7" take-up spools for 1/4" tape, also one 5.5". If you really get stuck finding one I'll mail one to you...all have the 3-pronged "cine" hub arrangement, (the usual domestic tape-spool arrangement), not NAB. See pic..

Steve A.


Thank you Steve ! i will have a look today if i did end up finding one at some time ,if i am not using it there and then i tend to put them together and forget about it !
I will have a look in my shed today /
The reel to reel were once easy to find not so these days ..i will get back to you on it ...i do recall i have a tape reel or two but empty ...lets have a look !
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mechanical video recorder

Postby Steve Anderson » Fri Oct 11, 2019 1:49 pm

Klaas Robers wrote:Wow Steve, you have a Philips tape spool. My heart opens....


I also have this...but sorry, the tape inside the box is BASF...I know, a crime!

I would guess going by the graphics, probably late 50's or early 60's.

Steve A.
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Re: Mechanical video recorder

Postby Harry Dalek » Fri Oct 11, 2019 5:13 pm

Steve Anderson wrote:Harry, I have a few empty 7" take-up spools for 1/4" tape, also one 5.5". If you really get stuck finding one I'll mail one to you...all have the 3-pronged "cine" hub arrangement, (the usual domestic tape-spool arrangement), not NAB. See pic..

Steve A.


I had a look Steve and i do have an empty reel which i must of picked up thinking i needed one Years ago ! arrr the memory loss ! So this is enough for tests when i get around to it .

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It seems i do have 2 small reel to reel machines first 2 photos the national it fires up seems to fast forward reverse play but not tested with a tape yet .


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The second Machine i have is a AIWA i don't have the power cord for this i might have to wire a new one in as the plug is not standard so really don't know yet if this works still .

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I also have doing a little show and tell here a Tv station video tape only has a little tape found about 8 cans at my local reuse shop this was the only one with a reel of tape init ...Knowing Troy he would more than likely have a machine to play it !
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mechanical video recorder

Postby Steve Anderson » Fri Oct 11, 2019 6:04 pm

It's been a long time since I was anywhere near an open-reel VTR, possibly 25 years. Most were Sony machines, BVH2000/2100/2200 and perhaps the 3000 series as I recall. All used 1" tape on 10.5" diameter spools. And (I think) a modified 'deep' NAB hub to cater for the wind/rewind torque from the spool motors. These were all C-format machines, there were others. Bosch (Germany) developed the B-format (I think also called the M-wrap format...I'm probably wrong...)

Back in the old days there was 'Quad' or Quadraplex. 2" tape, 14" spools, big heavy machines, developed by Ampex in the US, really the first practical VTR, though editing was a headache, mainly a no-no. They also needed a vacuum feed which sucked the tape into the correct shape for the video head(s).

Prior to that there was good old Vera, a product of the BBC Research Department. Humungous tape spools, linear tape speed was 120 ips, each 20" reel lasted only 15 minutes and only for 405 lines... (All from memory).

Ah! Those were the days!

First transmission of a VTR by the BBC...

https://www.bbc.co.uk/programmes/p01672b2

Presented by none other than Richard Dimbleby OBE, CBE.

I love the good old British BBC accents, does anyone sound like that anymore?

Steve A.
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Re: Mechanical video recorder

Postby Harry Dalek » Fri Oct 11, 2019 6:39 pm

More Lathe Tests today first Klaas mentioned to do a 200hz square wave recording ,i did this and also on the same cd a 400 hz you can see the Tracks and frequency difference looking at the recording light reflecting off the tracks ....BTW you can zoom in on these photos to see the tracks recording better if you click on them .
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I played this back at 33 rpm and looking at the frequency analyzer the 200 hz is showing 150 and 300 for the 400hz square wave tone i might by the sounds of it got the RPM record wrong and should be playing back at 45 RPM ...i am controlling the platter speed at 50 hz via a strobe disc but i might be controlling via one of the bands
Any case below is a short start which was the wanted 200 hz and then a jump to the 400hz longer which does sound off frequency ...i will check out the RPM problem tomorrow
EDIT ...........i just played them back could not wait at 45 rpm and results were frequency was just over 200 hz and just over 400 hz since the speed control is still not that correct on record this seems more like it .




Did some NBTV the recording on the below cd i could see syncs but again i will check play back speed tomorrow
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Re: Mechanical video recorder

Postby Klaas Robers » Fri Oct 11, 2019 7:54 pm

The 400 Hz square wave LOOKS not too bad, however you lack a lot of high tones. This is not so strange, as for audio records the tones above 1.5 kHz are attenuated during play back. So the normal play back electronics, that you are usung, does this. This is called RIAA correction. Look at Wikipedia: https://en.wikipedia.org/wiki/RIAA_equalization and read about it. During recording a reverse correction is done. This is called pre-distortion.

This is because low tones are generally loud, so the lower frequencies have to be attenuated in order to limit the sideway excursions of the groove. And high tones are in audio less loud, so they can be boosted during recording without any harm. The advantage is then that they can be be attenuated during replay, which gives much less hissing noise of the disc survace.

This is all done and true for AUDIO. But for video the spectrum of low and high tones will be much different. Gramophone records are never optimized for NBTV video signals. AND we don't know how the frequency characteristic of your recording head is. How Baird did this, I don't know. However in his days home recording of gramophone records was more common (by hobbyists). Philips had a gramophone recorder on the market in those days, a machine as large as a washing machine, which recorded onto zinc discs, or at least discs with a surface layer of zinc. At least one person in the UK had such a machine and recorded on it a nightly BBC Television-broadcast. Don Mc Lean captured that disc and restored part of the video (without sound of course).
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Re: Mechanical video recorder

Postby Klaas Robers » Fri Oct 11, 2019 8:13 pm

Steve, I remember that, before my time at Philips, say in the 1950's, researchers at the Nat.Lab. experimented with video recording on 1/4 inch tape in linear recording. The tape speed was about 5 m/s and they used as well those very large tape spools. But they had a machine with one spool low and one spool high, not one left and one right as the VERA machine did. This high-low configuration is general in 35 mm film projectors. In 1971, when I came at Philips, I have seen the remains of that machine and heard the awfull stories.

The real problem was getting the tape on speed and stopping it again, without tearing the tape. When something went wrong in the tape transport they got immediately 1 cubic meter of tape salad, which could only been discarded. Be aware that in helical scan video recording, the speed of the video head in the scanning drum is also close to 5 m/s, so little has changed. I am almost sure that the technicians at the BBC that built the VERA, encountered the same problems of starting and stopping and the occasional tape salad.
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Re: Mechanical video recorder

Postby Harry Dalek » Fri Oct 11, 2019 10:41 pm

Klaas Robers wrote:The 400 Hz square wave LOOKS not too bad, however you lack a lot of high tones. This is not so strange, as for audio records the tones above 1.5 kHz are attenuated during play back. So the normal play back electronics, that you are usung, does this. This is called RIAA correction. Look at Wikipedia: https://en.wikipedia.org/wiki/RIAA_equalization and read about it. During recording a reverse correction is done. This is called pre-distortion.

In some ways the waveform is still sort of squarish ..
I have done sweep tests before i might give this ago again and or record some higher frequencies and see how it go's ...i would think it is harder to record as mentioned above the higher frequencies ..but i should see what the limits are ..i am feeling its possible but i need more amplification for the higher end.

This is because low tones are generally loud, so the lower frequencies have to be attenuated in order to limit the sideway excursions of the groove. And high tones are in audio less loud, so they can be boosted during recording without any harm. The advantage is then that they can be be attenuated during replay, which gives much less hissing noise of the disc survace.


MMM yes i see the problem they cause with a video signal ... reduction in the strength of the lower frequencies i had not thought of .


This is all done and true for AUDIO. But for video the spectrum of low and high tones will be much different. Gramophone records are never optimized for NBTV video signals.


Record recording sounds primitive but its very complex learning a lot from the experiments ...On Baird recording phonovision we know worked but he was never happy with the results to go on with it ,i don't think he ever looked into it again must of been very draining to work on ....

AND we don't know how the frequency characteristic of your recording head is
.

I need to see whats possible here as i would be interested in using the Jermey Jago tape recording idea to record an AM carrier with NBTV on it ...might work for Records as well if it can manage at least 10 khz ?

How Baird did this, I don't know. However in his days home recording of gramophone records was more common (by hobbyists). Philips had a gramophone recorder on the market in those days, a machine as large as a washing machine, which recorded onto zinc discs, or at least discs with a surface layer of zinc. At least one person in the UK had such a machine and recorded on it a nightly BBC Television-broadcast. Don Mc Lean captured that disc and restored part of the video (without sound of course).


Amazing i had not heard of that ! Did some great work back then hard to repeat today !
i also never heard of Ferdinanc Plew and hes video gramophone Don should check with he's family if any recordings were kept in storage as i have never heard of hes system mentioned .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mechanical video recorder

Postby Steve Anderson » Sat Oct 12, 2019 12:46 pm

Klaas Robers wrote:...I am almost sure that the technicians at the BBC that built the VERA, encountered the same problems of starting and stopping and the occasional tape salad.

I think I have heard about that, maybe I read about it somewhere...the BBC were very cagey/shy in revealing the hiccups in development generally, only the final outcome (the success) was ever generally mentioned.

I stand corrected, I said VERA ran at 120ips, it was actually 200ips or 5.08m/s, all these different machines amazingly close together in tape-to-head speed!

I've posted the attached pdf before regarding VERA, so second time around for those that missed it...

Steve A.
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Re: Mechanical video recorder

Postby Harry Dalek » Sun Oct 13, 2019 4:20 pm

Steve Anderson wrote:I stand corrected, I said VERA ran at 120ips, it was actually 200ips or 5.08m/s, all these different machines amazingly close together in tape-to-head speed!
Steve A.


BBC on VERA ...Yes i notice that's a Human trait on not wanting to discuss fails in things people make work on ,its very important in fact more important than success so others will not go down the wrong road !

All good and well saying here it is works great but meaningless if its not explained ,the evolution of how thing were made is very interesting and great to see how what ever started from nothing but an idea .

Running the Tape fast passed a magnetic head is wasteful on tape but hell it would be satisfying to make some thing like this work .... :wink:
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mechanical video recorder

Postby Harry Dalek » Sun Oct 13, 2019 6:15 pm

I did a few more lathe tests today to test some ideas first 2 sweep tests
First cd was perhaps 5 sec between frequency sweep then a 10 second one both up to 10khz ,the thing i was checking also was on cd 1 i adjusted the duty cycle to 5 and the second sweep test i adjusted it to 50% just to see how the recording would handle both view the play back on my scope .
I could see the 5% duty cycle sweep didn't do as well as the 50%.
I also did a 400 hz square wave 5% duty cycle test i can see the waveform is not as good as the 50% i posted up ..
Below first the recording


The 10 second between start and end of each sweep run can be seen on the CD

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The 5% duty cycle sweep test 5 secs between sweeps lathe recording 1


Next the 10 second 50% duty cycle sweep test lathe recording 2



Now a Square wave at 5% duty cycle hardly looks like a square wave any more




Next i wanted to see how would Big picture handle a recorded 5% and 50% duty cycle 400hz sync pulses well at 5% from the lathe recording above it was useless such a mess not worth showing at 50% but it could handle the record recording waveform and could use it



As Klaas has mentioned looking at the sweep low frequencies are very strong and high weak so will play hell as is to any NBTV recording may be a high pass filter might help need some sort of evening things out on the recording ...Thinking of Baird he must of had similar problems and knew it i can't see things being any different from then to now as it just would not of worked unless he adjusted this problem before recording ...
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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