Mechanical video recorder

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Re: Mechanical video recorder

Postby Harry Dalek » Wed Jul 24, 2019 10:14 pm

Viewmaster wrote:Harry in fig 1 the drawing shows an important aspect of cutter design.
The burnishing facets are critical in order to get a
smooth, shiny finish to the cut disc.
Without them and the right angle of attack you
will not achieve smoothness and so low noise level.
I stoned my facets with an engineers stone but you
cab buy a cutter already made......eBay :)


This has me worried as to what your getting off ebay there does not seem to be only one seller i think could at least match that ebay quick knock up ,i am still thinking about this side of it Albert .
Yes i understand must be important a rough cutting tool more noise...mmm
BTW Albert did you have motor control of some sort since i am up to this ?
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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 Viewmaster » Wed Jul 24, 2019 11:25 pm

Yes Harry, my big DC motor had a rotating disc on its shaft with steel pegs around it.
Big electro magnets were pulsed from a CD carrying sync pulses only.

I had big troubles with this design as Mosfets driving the electro magnets had to be protected from back
EMF from the magnet coils. The trouble was mainly in my lack of knowledge. :D

But when it worked it did lock the motor within 2 seconds.
The motor drove the Dictaphone mandrel with a toothed belt to
prevent slippage.

There maybe more info on the various threads I had.

You should design so that the cutter angle to your recording disc is
adjustable. Also it's a good idea to have a voltmeter in the drive circuit to monitor volts so that
when you have achieved correct cut you can easily return to the same
drive that achieved it.

You will have much fun I can assure you, Harry, in between the headaches. :lol:
“One small step for a man,"......because he has Arthritis.
Albert.
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Re: Mechanical video recorder

Postby Viewmaster » Wed Jul 24, 2019 11:37 pm

Harry, as you know a cutting machine for discs is called a ' Lathe.'
The best forum (USA) for chaps cutting discs is this one,

The Secret Society of Lathe Trolls. It's a minefield of info
if you have the time to search and read what some of the master disc cutters do.

https://lathetrolls.com/viewforum.php?f ... a7c36a6a4f

Happy cutting.
“One small step for a man,"......because he has Arthritis.
Albert.
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Re: Mechanical video recorder

Postby Harry Dalek » Thu Jul 25, 2019 2:47 pm

Viewmaster wrote:Yes Harry, my big DC motor had a rotating disc on its shaft with steel pegs around it.
Big electro magnets were pulsed from a CD carrying sync pulses only.


Oh so an encoder there i can only think your syncing to the drum speed you used ?
BTW does the beast still exist ? some times i pull staff apart for reuse but if it works stored away in a box as you do :wink:

I had big troubles with this design as Mosfets driving the electro magnets had to be protected from back
EMF from the magnet coils. The trouble was mainly in my lack of knowledge. :D


Oh i see , its always learn as you go but you don't want to have to replace parts due to a design fault ...hate when that happens !

But when it worked it did lock the motor within 2 seconds.
The motor drove the Dictaphone mandrel with a toothed belt to
prevent slippage.


That's a good way to go i used a thin belt at first to much play for this project least i had something handy ! seem to work .

There maybe more info on the various threads I had.


Yes i have to reread them i found you had different subjects posted onit .

You should design so that the cutter angle to your recording disc is
adjustable.


Yes this was one of the first things i happened to think of ...the only thing i am still to work out is pressure of the cutter on the disk if what i end up with is to heavy at the end of the arm this might not be good putting the full weight on the disk that will be cut will if just cut to deep will it distort the audio ..the arm it will be on i can tighten so it can't be place full weight on the disk but its more a trial and error adjustment be nicer to have a fine adjustment here which i might have to work out .

Also it's a good idea to have a voltmeter in the drive circuit to monitor volts so that
when you have achieved correct cut you can easily return to the same
drive that achieved it.


Arr that's a good idea i was just thinking of a dial control but testing today its very tight would also need a fine trimmer here ...but this is manual adjusting viewing the strobe disk ... does not work via camera but to the eye the outer ring for 78rpm its very close but as will all manual motor control it will drift and i would expect soon as i started a cut this would effect the speed again ..so i am thinking it needs to sync on a cut or not ...not so much a problem to the ear but as we know video is a touch more fussy
I found the turntable speed from my geared motor to pulley i can get below 78 RPM and over 45 RPM ,but i can hear the motor at 45 so might not be wise to try that speed 33 and 78 seem fine

IMG_0101.JPG

IMG_0100.JPG


You will have much fun I can assure you, Harry, in between the headaches. :lol:


Yes could be more headaches but i do find it very interesting ..at the start i would just of been happy to record a sound ,i am just going to take it as it gos and for now see if i can record NBTV and play back the video as audio an see how bad it plays if at all that's a little goal for another next step :wink:
Looking at the needle today just seeing how good or bad can i shape one ...
Tried to do the wedge shape as in the cutting design angle might be off ok for a first go ...but i think with a protractor rig that might be possible.. all else fails off to ebay !
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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 Harry Dalek » Thu Jul 25, 2019 2:52 pm

Viewmaster wrote:Harry, as you know a cutting machine for discs is called a ' Lathe.'
The best forum (USA) for chaps cutting discs is this one,

The Secret Society of Lathe Trolls. It's a minefield of info
if you have the time to search and read what some of the master disc cutters do.

https://lathetrolls.com/viewforum.php?f ... a7c36a6a4f

Happy cutting.


OH i just had a look ...interesting one fellow was trying a stepper motor instead of a speaker hooking one up i had handy does seem to vibrate with some torque to the sounds .
I will do a bit of reading ! but i want to review yours as well tonight ...so you might get some questions .
Thanks Albert for that link ...
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 Viewmaster » Thu Jul 25, 2019 4:09 pm

The Edikow machine was scrapped.
I got sick and tired of it after X years playing with it and wanted to get
onto other projects.

My latest one was a panoramic view to the glory of old steam locos
including Stevenson's Rocket ! Track polarity switched using simple
micro switches and latching relays.

https://www.youtube.com/watch?v=ALKTE9Fgdtw

All much easier to do than cutting discs :D


BTW, to adjust total weight of cutter system either use a counterbalance
or a tension spring hooked high up although that tends to
pull the cutter to one side as it tracks across the disc.

When I started I simply took a 78 RPM gramophone needle and ground it halfway through
to make my first cutters. Whatever playback pick up you are using you must
match the groove patterns to suit it.
You cannot play 33RPM records with 78RPM needles !!
“One small step for a man,"......because he has Arthritis.
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Re: Mechanical video recorder

Postby Harry Dalek » Thu Jul 25, 2019 5:04 pm

Viewmaster wrote:The Edikow machine was scrapped.
I got sick and tired of it after X years playing with it and wanted to get
onto other projects.


That's fair enough some times you need the parts for something else ,yep need a change after working on the same thing ...but have to say that was a good one !

My latest one was a panoramic view to the glory of old steam locos
including Stevenson's Rocket ! Track polarity switched using simple
micro switches and latching relays.

https://www.youtube.com/watch?v=ALKTE9Fgdtw

All much easier to do than cutting discs :D

That looks like it was fun ! i hope none of the Trains went off rail switching tests ~! and that's great for that hobby if you have lack of space .


BTW, to adjust total weight of cutter system either use a counterbalance
or a tension spring hooked high up although that tends to
pull the cutter to one side as it tracks across the disc.


Oh that never came across my mind i kept thinking of some sort of screw adjustment up and down ...the spring might help me for that idea but weight idea could help too...i will again have a look when i get to that part of it .

When I started I simply took a 78 RPM gramophone needle and ground it halfway through
to make my first cutters. Whatever playback pick up you are using you must
match the groove patterns to suit it.
You cannot play 33RPM records with 78RPM needles !!


Oh that i never knew ...i did notice some players have a needle that rotates around with a little handle i always thought it was for when one wore out mmmm
So if i made a cutter as here from a sewing needle the play back should be a same size needle bit like that chart i posted up a while back .
i might also look into the tiny play back needles see if i can grind that to shape as is they do scratch the cd surface as is i have found ..
I also have some 78 Gramophone needles handy if need be ...any case some experimenting around this area for sure .
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 Klaas Robers » Thu Jul 25, 2019 6:29 pm

Harry, the cutter may cut a sharp V-shaped groove, while the play back stylus has a rounded top (bottom) and should touch the groove at both sides half way the bottom of the groove and the surface of the disc. That is the reason that both sides of the groove should be well shaped. The shape of as well the cutter, as well as the play back stylus is very well defined. You should find more about that on the web.

For play back 33 and 45 rpm records a small (artificial) diamond is used. For 78 rpm discs a saphire is used. The saphire has a more blunt shape as it should touch the grove much higher from the bottom. If you play a 78 rpm disc with the diamond it sinks deeper into the grove and you will hear distortion due to the fact that the bottom of the groove is less precisely shaped. On the other hand, if you try to play a 33 rpm disc with the saphire, it will not sink deep enough into the mini-groove and it will loose the groove and starts skating over the surface of the disc.

I don't know anymore why you cannot make a saphire for playing 33 rpm discs and why you cannot make a diamond to play 78 rpm discs, but there is some reason for it. May be that saphire is somewhat flexible and will damage the bakelite groove less, while vinyl is more flexible of its own and the hard diamond will not damage it during play back.

My grammophone player, a Philips 202 electronic, was the last Philips grammophone that supported 78 rmp. It came with one play-back element GP400 with a diamond "needle" for 33 and 45. After some time I got a second GP400 element and a friend of mine at Philips, who did these things in his past, exchanged the diamond tip for a saphire tip for 78 rpm. Now I can again play back those old bakelite 78 rpm records.

When I came living in Valkenswaard, we had here a delicate factory: Philips Diamond tools. It was no more than a few 100 metres from my home. They made draw stones for the production of the very thin tungsten filaments for incandescent lamps, but also diamonds and saphires for grammophone stylussus. At a certain moment the factory stopped and they built there private homes.
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Re: Mechanical video recorder

Postby Harry Dalek » Thu Jul 25, 2019 8:29 pm

Klaas Robers wrote:Harry, the cutter may cut a sharp V-shaped groove, while the play back stylus has a rounded top (bottom) and should touch the groove at both sides half way the bottom of the groove and the surface of the disc. That is the reason that both sides of the groove should be well shaped. The shape of as well the cutter, as well as the play back stylus is very well defined. You should find more about that on the web.


Yes i will have to do some more reading ,i would rather try and make the cutter but i might double my chances if i can find a cutting stylus i like on line ..
I can see from the below drawing the cutter should be smooth ruff cut will cause noise from the sides ..i have seen some good and bad results on the net but in both cases its possible to knock something together that works this may have to be a bit of trial and error evolution learning from any mistakes .

Something we know the play back Stylus will scratch the tracks if you by mistake bump the play back arm on a record ..and i have noticed it will scratch a track on a blank cd if used via the cutting arm something i am wondering if its possible to play back ..or stay in that scratched track ...not the correct way of doing things but never know we are talking a different type of cutting surface here a cd not a record which seems harder . pretty much the edison idea he scratched the sound on foil and used the same stylus needle to play back .


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For play back 33 and 45 rpm records a small (artificial) diamond is used. For 78 rpm discs a saphire is used. The saphire has a more blunt shape as it should touch the grove much higher from the bottom. If you play a 78 rpm disc with the diamond it sinks deeper into the grove and you will hear distortion due to the fact that the bottom of the groove is less precisely shaped. On the other hand, if you try to play a 33 rpm disc with the saphire, it will not sink deep enough into the mini-groove and it will loose the groove and starts skating over the surface of the disc.


Its a large learning curve about records and record play back seems simple at first but is pretty complex to do it correctly over 100 years or so years of development .

I don't know anymore why you cannot make a saphire for playing 33 rpm discs and why you cannot make a diamond to play 78 rpm discs, but there is some reason for it. May be that saphire is somewhat flexible and will damage the bakelite groove less, while vinyl is more flexible of its own and the hard diamond will not damage it during play back.


I think i have a double sided stylus if i find it i will have a look under the mircoscope ...i suppose the recording speed via the tracking recording arm with those speed differences of 45 33 78 rpm ..i would think the tracks have to be narrower or wider with the speed change ...as with you mentioning the depth for the stylus for 78 and less for 33rpm...to keep recording time to maximum...makes my head hurt thinking about it ..i will stick with 78 and see how that gos !

My grammophone player, a Philips 202 electronic, was the last Philips grammophone that supported 78 rmp. It came with one play-back element GP400 with a diamond "needle" for 33 and 45. After some time I got a second GP400 element and a friend of mine at Philips, who did these things in his past, exchanged the diamond tip for a saphire tip for 78 rpm. Now I can again play back those old bakelite 78 rpm records.


I have a broken one that could play 16 rpm i have not seen any record in that format...its good you can still get stylus for your player older they are i suppose it harder these days to get spares or it becomes costly if they are rare .

When I came living in Valkenswaard, we had here a delicate factory: Philips Diamond tools. It was no more than a few 100 metres from my home. They made draw stones for the production of the very thin tungsten filaments for incandescent lamps, but also diamonds and saphires for grammophone stylussus. At a certain moment the factory stopped and they built there private homes.


That would of been handy if you could buy them there buy a few in bulk ...like every thing nothing lasts for ever sad as it is .
I can by the way the difference between the edison way and modern way for a record stylus image below
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Re: Mechanical video recorder

Postby Steve Anderson » Fri Jul 26, 2019 3:21 pm

Viewmaster wrote:I had big troubles with this design as Mosfets driving the electro magnets had to be protected from back
EMF from the magnet coils. The trouble was mainly in my lack of knowledge. :D


That's kinda odd Albert, most medium & hi-power MOSFETs have 'back EMF' diodes built in. As an example I attach the pdf for a commonly used MOSFET with NBTV, the IRF540.

On the first page there's schematic of the internals showing the reverse diode (usually Schottkey) and its ratings are listed lower down...

Steve A.
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Re: Mechanical video recorder

Postby Viewmaster » Fri Jul 26, 2019 4:30 pm

Hello Steve.
My electro magnets were about 40mm dia and about same length.
Quite hefty. I had diodes across them but they blew my mosfets at
irregular intervals.
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Re: Mechanical video recorder

Postby Steve Anderson » Fri Jul 26, 2019 5:10 pm

Hmm, I still find that surprising. What MOSFETS were you using? They are generally so reliable these days. I recall the early days of them when you just had to look at them and they went 'POP'.

The only other factor I can think of is somehow the gate-source/drain voltage rating was exceeded, usually around +/-20V.

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Re: Mechanical video recorder

Postby Viewmaster » Fri Jul 26, 2019 9:54 pm

Your straining my memory now. it was over 10 years ago.
( My word, how time has flown by. :) )

IRF 5** or 6** series used. Not sure, but all scraped long ago now.
Probably your reasoning is correct though.
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Re: Mechanical video recorder

Postby Viewmaster » Fri Jul 26, 2019 10:22 pm

Harry, conversing with Steve about the good old days ( :D )
has reminded me of something else.

When I cut the wax dictaphone discs they never ran completely true
in the vertical plane, even after turning them true,
which would have led to unwanted vertical noise.

I adopted what many profesional lathers do and had what is called an
'Advanced Ball.' This is a small steel ball mounted on a vertically adjusted screw
which is just ahead of the cutter.

This ball rested on the wax cylinder taking the
weight of the cutter head (after being near in balance ) and so ensured
that the depth of cut was always the same no matter how much the wax varied.

It also acted as a burnisher for the wax surface just before cutting.

Your CD's should not have this problem if they run true but bear in mind that
some professional machines do have advance balls when cutting flat discs.
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Re: Mechanical video recorder

Postby Harry Dalek » Fri Jul 26, 2019 11:55 pm

Viewmaster wrote:Harry, conversing with Steve about the good old days ( :D )
has reminded me of something else.


No problems any hints are always welcome ... :wink:

When I cut the wax dictaphone discs they never ran completely true
in the vertical plane, even after turning them true,
which would have led to unwanted vertical noise.


Oh i see i would not of thought a slight angle being off would cause that but i suppose with any mechanical recording and play back it would cause noise looking at a record track up close ..every mistake dust so on ..but it is mechanical touching as bad as it gets ,its amazing it works as well as it can .

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I adopted what many profesional lathers do and had what is called an
'Advanced Ball.' This is a small steel ball mounted on a vertically adjusted screw
which is just ahead of the cutter.


I will look into that never heard of it have to a google !

This ball rested on the wax cylinder taking the
weight of the cutter head (after being near in balance ) and so ensured
that the depth of cut was always the same no matter how much the wax varied.


This i had on mind as in cut depth , i was thinking should be kept constant range for tracking and amplitude .

It also acted as a burnisher for the wax surface just before cutting.


OH a bit of flattening and polishing ...i must admit i never looked into a wax drum as to what it is but have noticed the different lathe cutters for different materials

Your CD's should not have this problem if they run true but bear in mind that
some professional machines do have advance balls when cutting flat discs.


Well knowing some thing new is always good ! Albert as far as my go here just trying parts a step at a time ..here now the lathe tracking arm and cutting head need to be worked on the cutting stylus not so important yet just some thing used that will do the job if bad that's ok can be replaced.... movement track cut and keep the turntable at correct speed are things i have to look at ....
I didn't have much time today but looked into the idea of the simple stylus cutting the track or scratching them in since its not a dedicated lathe cutter but using the stylus for making the tracks seems to work since the grove now matches the stylus correctly ..seems fine for this .....but as for using it for modulation after i will find out ...if doesn't work back to something else .
CDs are much easier the cut than what records are made of it seems .
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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