The mechanical video recorder PhonoVision

[dalekmoore2007]

Well i think Baird used a 30 line 5 frames a second system on a 78 rpm record
Here again 78 rpm i am Trying 32 line 12.5 frames a sec by no means perfect yet just my first results or second really i had to change my embossing head for NBTV from SSTV its bandwidth for recording needed widening .
I am using a 100 watt amplifier to feed the video to a standard ceramic play back cartridge it embosses the track and video and i use another of the same type ceramic cartridge for playback .
Due to fiction of embossing the recording on the soft cd plastic on play back the platter runs faster so the video also i use a magnet eddy current braking slow the record back to speed to get sync or really best i can its very tight adjustment ...it will do for these experiments.
Not perfect and i need to adjust my video levels this was just a quick knock up for testing i need contrast and brightness controls ..
I know its not great yet but i am very pleased so far .You tube link videos below
https://www.youtube.com/watch?v=wAua8z4Onq8
https://www.youtube.com/watch?v=hiPvadVCw7o

[dalekmoore2007]

The recording side ,i use a 100 watt amplifier the NBTV video is amplified and feed to a ceramic tone arm cartridge which embosses the tracks and the video on the CD plastic .
https://www.youtube.com/watch?v=N6oVfdVJ99E

The artifacts look just like ones on restored Baird disks.

[dalekmoore2007]

Originally Posted by merlinmaxwell

The artifacts look just like ones on restored Baird disks.

Since i am using a 78 Rpm AC motor i seem to have the same low frequency rumble noise ..

I am pretty happy with the results so far ,i was not expecting to be able to record and view any thing Baird gave up on 12 .5 fames a sec and dropped it to 5 frames

If any one has tried to play back as is the phonovision recordings you would find its hopeless they need a lot of computer processing to view any thing i don't know if its because baird didn't use sync pulse but i am and using nothing but an amplifier which does need adjusting for contrast and brightness for play back have to get this level right .

Baird never really gave any demonstration on phonovision apart from explaining what the sound on the record was showing ,i don't know if he was ever able to view the results or they were just to poor to show the public but any case the experiments i am doing do show what he did would work he was amazing man to do all this in late 20s with just what they had at the time is beyond me ,i just took the idea and thought with todays technology it should be easy and it must be but i found this the hardest project i have ever tried .
If i manage to get it better my goal is to increase the recording to 60 line i more than likely will have to also increase RPM speed to record the video bandwidth at the moment its the same as Bairds 78 RPM .

[peter_scott]

In the lecture "Restoring Baird's Image" I think you can see one rather obvious problem with his mechanism. He used universal joints without taking account of their non-constant velocity nature.

Peter

[dalekmoore2007]

Well Peter for us looking back i suppose its easy to see this problem you mentioned once you know now i do ; ), all in all he's mechanism was a beast.
I would think recording friction would not of been a problem for him causing play back speed change with the gearing as with my attempt but he's use of gears the noise must of been a problem if anything ?
Any one trying PhonoVision or looking into it just has to be amazed at for one Baird coming up with the idea and the DIY inventing.
I know he was never happy with the recordings as far as images and i wonder if he ever saw viewable results ...thanks for the link i will review it.

I have the book "Restoring Baird's Image" a bloomin' good read. Your efforts are amazing, I especially like the "power driven" ceramic cartridge. Just how much can it take before going into destruct mode?

[kalee20]

Well, full marks for achieving what you have!

I think there are, in existence, a couple of discs made off-air of Baird TV transmissions, by somebody using a home disc recorder. They wouldn't have suffered from the cyclic speeded variation described by Peter Scott, and although not hi-fi, the disc cutters of the day (coming of the domestic tape recorder killed them off) would have been equipped with motor and cutting head designed for the job.

Like you, I'm full of admiration for Baird. Turning to TV, after his forays into jam-making and bed socks, and being able to lay claim to the first transatlantic TV transmission... The man just 'got on with things.'

[dalekmoore2007]

Originally Posted by merlinmaxwell

I have the book "Restoring Baird's Image" a bloomin' good read. Your efforts are amazing, I especially like the "power driven" ceramic cartridge. Just how much can it take before going into destruct mode?

Well i have used the full 100 watts and does not seem to bother it at all ,when i was working this out i found out in the past they used ceramic cutting heads for records and old records had on them saying they were cut by them at 70 watts.

My thing was i wanted to get away from my DIY cutting head due to i need now its full audio bandwidth of a modern cutting head ,older ceramic heads seemed no better than my home made one up to 8 khz .
Modern up to 20 khz ... I poo pooed the advice you can't use these in reverse ! mine is used untouched just used in reverse .
No wonder baird gave up on 12.5 frames a sec hes cutting head must of poor bandwidth wise .

[dalekmoore2007]

Originally Posted by kalee20

Well, full marks for achieving what you have!

I think there are, in existence, a couple of discs made off-air of Baird TV transmissions, by somebody using a home disc recorder. They wouldn't have suffered from the cyclic speeded variation described by Peter Scott, and although not hi-fi, the disc cutters of the day (coming of the domestic tape recorder killed them off) would have been equipped with motor and cutting head designed for the job.

Like you, I'm full of admiration for Baird. Turning to TV, after his forays into jam-making and bed socks, and being able to lay claim to the first transatlantic TV transmission... The man just 'got on with things.'

Yes i know of that home recording,that would of been 12.5 frame 30 line i know they were recorded off air at the time some one in Europe picking up the transmissions and happen to have a record lathe...i wonder if again he or she tried to play it back to a monitor you would think that would of been the plan..

I looked at trying to play back the old phonoVision recordings as is but i had no luck which make's me wonder if Baird was able to review the images recorded maybe i should of should of played around with the levels video like this is very fussy ...I would like to think he did see he's recordings sad other wise ,i can't see how he stuck with the idea with out any results and it is now shown video was recorded .

So many problems in doing this but very satisfying i am having a look at more experimenting today love the idea of keeping Bairds idea alive and if any one wants to repeat the idea its possible old school Analog !

[dalekmoore2007]

I have 2 videos here to view The first another go at NBTV video recording displaying here on NBTV v 1.0
https://www.youtube.com/watch?v=XcsmT8cGZeo

Next to see how well the sync pulses are recorded ..noise does play hell with them !
https://www.youtube.com/watch?v=YOXBGaQoXdc

[dalekmoore2007]

I was recording as in Baird Style AM to the true PhonoVision Idea apart from it being NBTV standard 32 line 12.5 frames a sec and has a Sync pulse..... today i swapped to Pulse width modulation recording and i seem to be getting much better results as far as recording Grey scale so must be doing a better job and using the Bandwidth .
Got to do something about the platter speed spoils it might have another look at stepper motor here .
I would look into an oscillator feeding another high wattage amplifier to a transformer to the asynchronous Ac motor the frequency in theory should adjust the frequency ...but if i don't have the voltage i don't have the torque .
Results below end of disc so signal levels change at the end of the disc

https://www.youtube.com/watch?v=hUpUE84MzpI

[dalekmoore2007]

I have been thinking about the platter motor again my nemesis ! :x

Experimenting with PhonoVision i now know why Baird used a monster of a gear set up to record hes video he wanted no speed change on play back of hes discs ...genius of cause !

Since i can't do this will or want i have to nut out a better solution to the speed change problem on recording playback ...(recap embossing a recording on a cd or dvd the fiction of this causes a speed drop RPM drop the asynchronous motor is not to great torque wise )
The effect on playback is correct RPM speed but the the recorded video is off sync running fast steady enough but slanted rolling ..i don't mind the wobble but a wobble in one place is better than this .

I was experimenting today with the idea a DC motor pulley connected to the asynchronous motor is sort of a superior way to adjust speed than the one way only magnetic eddy current braking at least on record i can record faster so on play back i can slow the recording back to speed.

May be with the extra torque of the dc helping the AC Platter speed may just compensate for the embossing recording and keep RPM true .

Doing a quick hook up and where i would position the motor if it worked it seems to work better than i expected ,i choose a DC motor that also has a AC signal output i am not sure what theses motors are called i have 3 one was from a old laser disc player ...Having a AC signal to view on the scope i noticed pulley connected to the ac motor and both ac and dc on the dc could control the speed of the AC and it didn't seem to drift but have to double check my scope settings might just be locking ...any case the idea is the Asynchronous mains motor stops The Dc from drifting to what ever speed its set at ...That would be nice but i will look more into this tomorrow if this is really the case......some speed control as i know this will do is a benefit much better than what i have now and an easy addition to the project .

I found out also the last posting Pulse width modulation recording was 45 RPM not 78 so that's interesting !

[dalekmoore2007]

Ok i got my DC add on motor control built in and wired up belt connected to the asynchronous motor ,so i can now remove the eddy current idea which at least at the time slowed the platter an amount to view my recording.
The idea was explained in the last post so this is more it in images ,i would if any thing expect better results on play back to have at least some dual speed control ...until i hook up a recording to check i will see if the coarse potentiometer is enough i may add a fine if needed .
The sinewave signal out of the motor may be useful for feed back if i can be bothered going down that road....i didn't have much time today just enough to finish this idea so no tests till later in the week .

It working in the You tube video
https://www.youtube.com/watch?v=okCX9TEXIyY

[dalekmoore2007]

PhonoVision 2020 ; ) will it sell ? ; )

Today i gave the new idea a good run to see whats up, i can see i can't really go any further as far as the platter speed control..... explaining ...The dc motor is handy replacement for the eddy current braking and as far as helping to stopping drift a bit i found even if the asynchronous motor is doing this the speed of the recording changes due to the tracks being shorter as it spirals in as shown in the second video so there is a constant speed change from start to end of the recording no matter what i do controlling the platter speed ,perhaps no problem for audio but video it seems to be another story .. Baird must of had the same problem ..i would think a cylinder would be better idea for this as all track lengths are the same on a cylinder. I also found due to the angle of embossing head unchanging in the recording the start to the end of the recording the video levels are higher at the start to the end ..so this PhonoVision thing is pretty hard lots of problems no wonder Baird walked away any case now i know !
https://www.youtube.com/watch?v=_CAXZoJcIBQ
https://www.youtube.com/watch?v=xpGlN8fLJKw

[af024]

I'm truly amazed by this and intrigued when it comes to operating a ceramic cartridge in reverse to provide the recording function. Have you had to modify the stylus/stylus shaft/coupling to provide the necessary downward force to make a cut/emboss?

Amazing results I have to say.

[peter_scott]

Now if you used a phonograph cylinder approach instead of a disc you wouldn't have the speed issue.

Peter

[dalekmoore2007]

Originally Posted by af024

I'm truly amazed by this and intrigued when it comes to operating a ceramic cartridge in reverse to provide the recording function. Have you had to modify the stylus/stylus shaft/coupling to provide the necessary downward force to make a cut/emboss?

Amazing results I have to say.

Hi its just a standard stereo ceramic cartridge untouched reason i used this as its cheaper than the magnetic type,but you need a 100 watt amplifier for the ceramic ...the magnetic i made one from an old tiny dvd stepper motor from the axis movement it can be powered right from the audio output of your laptop ! so thats the difference ! I wanted the ceramic cartridge also because it had a 20khz bandwidth my home made magnetic cartridge could only do 8 or 9 khz .I found out also testing a 50s ceramic cartridge on a frequency sweep test it could only do 8 khz as well..no wonder Baird had trouble ...nearly 100 years later the bandwidth has doubled on these devices ...
But it does not mean you can record all this bandwidth i know i am still lacking bandwidth in the recordings which might be due to some thing else on the play back side .. i started with AM and swapped over to Pulse width modulation which seems better for this ..i am just out putting the play back cartridge which BTW is the same type at the embossing cartridge to an amplifier its out put to the lap top via a trimmer ..i really should be using some wide width bandwidth opamps as in NBTV circuits for this as i really don't know how well the amplifier is doing on the higher frequencies
Yes its embossing scratching the recording tracks and the audio on the tracks as you think the weight of the embossing head is sort of critical for play back not enough weight it will emboss but not enough for play back i was lucky on this second lathe as the metal arm i used was spot on it works as is ..the first first i had to add say a washer or 2 or tiny little magnet to add weight .
Any other questions just ask as it was what i was asking my self building this thing glad to help. a recording video below gives you an idea of the speed and such
https://www.youtube.com/watch?v=w_1zbNTjMXU

[dalekmoore2007]

Originally Posted by peter_scott

Now if you used a phonograph cylinder approach instead of a disc you wouldn't have the speed issue.

Peter

OH yes i came to that conclusion yesterday had me beat why the record should be at one correct speed and is not on different positions on the record...Baird must of had this problem as well a record is a record nearly 100 years later or not .
I suppose you could fix the speed via the motor control to geared record lathe arm to adjust the voltage to the motor for automatic speed adjustment as it embosses the record ...one of the geared cogs for the lathe to adjust a pot be a bit of trial and error but possible solution .

As you say a cylinder is so much easier idea ...just the surface of the thing your using to record on has to be correct or you will have to cut not emboss.

[dalekmoore2007]

Originally Posted by af024

I'm truly amazed by this and intrigued when it comes to operating a ceramic cartridge in reverse to provide the recording function. Have you had to modify the stylus/stylus shaft/coupling to provide the necessary downward force to make a cut/emboss?

Amazing results I have to say.

I forgot to mention in the last reply above the reason this works on Cd and dvds is the plastic they use on them they are easy to scratch reason you don't need a special cutting stylus.
BTW notice the level difference from start of recording to the end on the second video that was a problem too
https://www.youtube.com/watch?v=ICje3eKTD6k
https://www.youtube.com/watch?v=t71AvrwoDvg