Mechanical video recorder

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Re: Mechanical video recorder

Postby Harry Dalek » Thu Aug 08, 2019 7:20 pm

There are a few things i need to work on now i tackled redesign number 3 of the lathe today .. so far is it vibrates with a heap of torque and sounds very good with a speaker cone to .. so i would expect higher volume recorded at least....the idea has been used before but not this small its a stepper from a dvd drive .
What i really hope for is a wide bandwidth record but see how number 3 go's.
I will more than likely have a look how well it makes tracks and records tomorrow .
I am also getting parts together to tackle the speed syncing i will use the strobe disk as an encoder reflective idea to opto switch for the mechanical feed back ...that's the start of the motor control at least
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Re: Mechanical video recorder

Postby Harry Dalek » Sat Aug 10, 2019 9:10 pm

I started working on motor syncing for now 45 rpm swapped the lid around for a place to mount the circuit board make things a bit neater .
My strobe disc i am using as an encoder is printed out on printer ink no good for an IR reflective opto switch it would not work ,so made a visible version with a laser and photo transistor ,looks out of focus in the images but its a fine dot focused to the size of the middle encoder strips .
Testing it with a frequency meter to Steve's circuit below i now know 50hz is 45 rpm .
Harry's LM311 A.gif
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I am used a 4060 crystal 3.2768MHZ clock to 2 74hc4040's again Steve's past circuit is being reused for another project ! didn't have to think about it known working idea .
So that's built working over designed i suppose here ...look into that later if the extra locked frequencies might come in handy .
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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 » Sun Aug 11, 2019 6:29 pm

Record turntables often had stroboscopes on the outside rim of the platter with four 'stripes', two for 50Hz supplies (33 &45) and two for 60Hz. They were illuminated by a neon (later LEDs) so that at the correct speed the stripes appeared stationary. The reference was usually the local mains frequency which isn't too bad, or a crystal oscillator divided down down to a suitable frequency in the higher priced models.

With direct-drive turntables they are inherently crystal controlled and usually provide no fine adjustment of speed. Higher priced ones did so you could 'tune' the record to your piano if you wanted to play along.

Steve A.

The turntable in the photo can also play 78s, but no third pair of strobe markers...I guess 78s weren't that accurate to start with...
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Re: Mechanical video recorder

Postby Harry Dalek » Sun Aug 11, 2019 8:11 pm

Steve Anderson wrote:Record turntables often had stroboscopes on the outside rim of the platter with four 'stripes', two for 50Hz supplies (33 &45) and two for 60Hz. They were illuminated by a neon (later LEDs) so that at the correct speed the stripes appeared stationary. The reference was usually the local mains frequency which isn't too bad, or a crystal oscillator divided down down to a suitable frequency in the higher priced models.

With direct-drive turntables they are inherently crystal controlled and usually provide no fine adjustment of speed. Higher priced ones did so you could 'tune' the record to your piano if you wanted to play along.

Steve A.

The turntable in the photo can also play 78s, but no third pair of strobe markers...I guess 78s weren't that accurate to start with...


Hi Steve yes that sounds like its possible from your posting and the way to go.
I was just testing the motor control via a bistable switch feed back from the encoder and a 50 hz crystal clock dropped down from your 4040 circuits you drew up for me a while back ..its very jerky looking at the out put of the 555 bistable you can see to many pulse width changes this would not be good and isn't .
It was about the same as running for just DC lm317 adjustment by passing the 555 bistable and just using the 50hz crystal clock to switch the motor Transistor so a lot smoother than using any feed back but that has not real motor control ...
I have only tried motor control on a polygon mirror and that worked well but i know at the time the pulley had to be adjusted for correct speed control but here it has to be tight to drive the lathe or it will slip ... also being a geared motor is something new also .
May be i should of went the old 4046 way for control but any case will look into it again later this week.
(edit) ...i think a good idea would be match the pulse width from the clock to the encoders this might be helpful perhaps ...
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Re: Mechanical video recorder

Postby Harry Dalek » Fri Aug 16, 2019 7:15 pm

I got my embossing needle today ...i was more getting this out of interest ! the type of recording stylus depends on what you are using to record on since i am using something soft enough pretty much scratching the sound on i have to use some thing as i was doing .
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Looking at the Needle it has a slightly elliptical cut to it than a sewing needle but i would say around the same size it seems much bigger than the gem stylus 2 i was using of late but the point might be close .
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The stepper motor as a recording cartridge seems to work ok but looks like i will have to pull things to bits again to try this stylus or make a new one with it i can bolt on to test against .
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Re: Mechanical video recorder

Postby Harry Dalek » Sat Aug 31, 2019 10:47 pm

Sorry for any one following this I had little time last 2weeks but will get back at it .....also had to repair my store record player it's really needed just to double check the recordings ..I found out my quick knock up player worked but did not give me the correct play back quality another thing to rethink start again on.
Found the 30's clipping interesting as records were the tape recorder of the time.
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Re: Mechanical video recorder

Postby Harry Dalek » Fri Sep 06, 2019 11:00 pm

At last had a bit of time to work some more on the recorder...when i left off my record player had broken just some broken wire's easy fix but before it did the last recording was not to bad the first stepper motor lathe head seems fine .
I have made another for the new cutting or embossing stylus but put that aside for a bit knowing this works and i redesigned the arm end for it trying to make it more stable during embossing and not scratch to deep or cause vibration also a shallow emboss is not good either for play back stylus.
Below first two videos what i have got up to i read a lot of people cutting records use lubrication liquid of some sort i jut used some oil here



Below a radio recording this isn't to bad now for some thing like voice this was at a slow 33rpm


Trying a frequency sweep and video recording i can hear there is some torque problem still speed difference when embossing the friction is slowing the disc down perhaps tightening the rubber pulley might help or recording a touch faster might compensate...i am finding this all very interesting as its the hardest mechanical thing i have ever tried.
Might be a good idea to record say 400 hz one frequency and see how it handles this maintaining this frequency ,so maintaining constant speed on record is my big problem ..i have removed the speed control idea for now that was not working at all .
Another idea to see whats up on the constant recording speed is view a strobe disk while recording ...any case my minds on this problem at the moment might mean a redesign ...have a head scratch and think about it :roll:
BTW coming across other recording things i noticed baird had used the idea for Noctovision recordings
https://www.americanradiohistory.com/Ar ... 7-06-R.pdf
Also came across Alberts Edikow posts in phonograph makers below
http://www.christerhamp.se/phono/noble.html
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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 » Wed Sep 11, 2019 8:40 pm

My head scratching thinking time is over and back to work tomorrow ...i have come to the conclusion i really have to get the speed control problem correct so am going to have to tackle this again ,and see if i can do this a bit better .
When recording .....speed will always drop with the extra fiction automatic speed control is what i would rather ...i could view the strobe disc and try and adjust the motor speed with a fine control Precision pot it might get close or less drift but manual control it will always drift the only a matter of time .
Looking at my strobe disc i can see drift is less on 33 RPM than 78 RPM ..
I am going to print out some more strobe disks but stick to one speed software below .

Ideas other than what i am doing come to mind

Off what i am doing at the moment .. an idea on reusing records i wonder if like tape recorders you could have a erase head before the record head or erase stylus in this case high frequency feed fed to the stylus to wipe cut out the old recording ? the record stylus behind the erase stylus then cuts a new recording which i would expect be to a deeper track...Oh well just an idea that i thought might work .


Also a portable record tracking arm for any record player using the tracking arm mechanism from an old ink jet printer i think you would still have to gear the motor speed down but be usable for normal sized LP record ...

I do like the idea a few posts back using a record that already has tracks cut any old record ...a player stylus arm that is also attached to a a cutting head some distance to the recording platter ...say like a CD on a LP record the LP tracks used to move the record stylus cut on the cd ...only problem i can think of the LPs music might cause it to be recorded on the Blank ? etch a sketch fashion ? :lol: thinking aloud sorry ! :wink:
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make any RPM strobe disk !
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Re: Mechanical video recorder

Postby Harry Dalek » Sat Sep 14, 2019 11:20 pm

I began work on the platter RPM syncing again today removed the lathe stylus for the work .
Tried the IR reflective opto switch but as i thought no good for ink jet printed encoder disc's seeing right passed the ink if it were not there .. so had to reuse the red laser and and light sensitive diode positioned the laser to focus and hit the 33rpm part of the encoder i found using this at 45 rpm speed gives me 50 hz pretty much one of the out puts of the 4060 crystal oscillator to one of 4040s ,this is sort of what i was trying last time but i had trouble with room light effecting the light sensitive diode so effecting the laser pick up , the laser sensor seems better positioned this time room light change does not effect it .
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Haven't checked the option of the frequency results pointing the laser at the strobe disc light brake's at 45 and 78 rpm ..
Having 50 hz is an easy fix i use it to also light a diode for the strobe disc visual indicator instead of using a 240 v room light ,i have a little mirror to view bottom of the disc .
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I also put in a fine trimmer for the platter speed and mounted the board and controls ,the main board is out for circuit changes
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I have had it on manual speed control better than in the video oscillating here a hz any case reworking the speed control circuit i noticed a few mistakes to what i have made before .


The encoder pulse is a little jerky see it more on the crt scope
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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 » Tue Sep 24, 2019 11:09 pm

I had a little success a few days ago on SSTV i have a little app on my android phone i never noticed before the receiver software has a few options for SSTV system types you have to air transmit the signal to the phones mic not ideal but does work if levels are high enough .
So i had some way to test a colour 32 sec cd embossed recording the record speed still swings around 1 or 2 hz but its close ..i found i had no luck on the 32 sec receiving setting but when i swapped to the raw setting on receive ...which i have never heard of i manged to see the image via the recording ...i am not sure what RAW is but i think it locks onto one sync pulse if frequency is off or not and just lines all the video up there on what ever system you choose to it ,i need to do more testing here ...the image is B/w .
Just found this on raw mode Old B/W or unsupported modes can be viewed in "Raw Mode".
I had a good image on the phone for what it was a weak air hook up but didn't know i could keep save the image and further tests were just weaker phone battery dying as well so i think the play back times are limited to well how deep i embossed the recording ...
The lap tops audio output on that recording was too low as well .lots of problems still but i will keep at it and show a recording image next time i test .
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Robot36 - SSTV Image Decoder 1.38
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Re: Mechanical video recorder

Postby Andrew Davie » Wed Sep 25, 2019 4:50 pm

Harry Dalek wrote:I had a good image on the phone for what it was a weak air hook up but didn't know i could keep save the image


Try holding down the power and volume-down buttons together for a few seconds. On many Android phones, that will take a screenshot for you.
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Re: Mechanical video recorder

Postby Harry Dalek » Thu Sep 26, 2019 12:06 am

Andrew Davie wrote:Try holding down the power and volume-down buttons together for a few seconds. On many Android phones, that will take a screenshot for you.


Hi Andrew !

Oh like my ipad my daughter showed me that trick a while back i had no idea ! but not tried it on the phone it did have a save file but i didn't know had not played with this app before ! live and learn ! :roll:

My mistake more was that my best first recording would be lost and it the cd embossed recording would go down hill after each play !
arrrrrrr !

So the recordings here are pretty crappy but least i have some thing from the first ever try ...
Photo below i would of been over the moon with ....but its just a air transmit computer to android phone but it shows the test card i was using as the record looks dreadful after a few try's ....gets warn very quickly gets very scratchy might be also because it was a laptop to to my record lathe stylus and a lap top here gives very low levels so a weak recording ...with my little radio to it i can hear it when recording laptop nothing just fingers crossed its loud enough to scratch a recording on the cd .

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Now for the recordings very very bad but may be the first sstv recordings on a record who knows ? on my first go i could read the letters but after a few plays every thing is washed out i have to make a few more recordings different modes and see ...air recording also does not help at all so its a wonder all this worked at all ....
BTW you can just make out the CQ SSTV in the bad recordings :shock:
I was recording 32 sec colour robot here to 33 RPM....Lets hope i can only go from bottom here up to something a little clearer, i hope i have some time this weekend and try again now i know what will work ...who knows might manage NBTV but its a long way to the top if you want to NBTV ! :D
BTW again ...i changed the record lathe design end again so it can move with the slight up and down movement so it can move with the cd if its not 100% flat and has a slight wobble it helps kept the record cd speed while embossing other wise not having this the stylus will dig in with different changes in wobble and either not cut in or cut to deep again either way stuff the recording up and changing the constant speed ...there were lots of problems at times with this little beast !
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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 Sep 26, 2019 5:53 pm

Another try today ! before i go out bit better but more work !
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Re: Mechanical video recorder

Postby Harry Dalek » Wed Oct 02, 2019 11:58 pm

I wanted see some thing as i noticed an experiment that was lacking on the forum just as a test to see if a good cassette recorder could record and play back NBTV ,it never really crossed my mind if it could be done or not i know its fine for SSTV more so my PHILIPS-D-6920-MK2 which has pitch control so can control the play back speed ...comes in handy for SSTV to correct any slant on play back .
I tried as i might to record NBTV and play it back but it must be doing a bad job at recording the sync well i only had one go at it then my gear that controls the rewind and fast forward fell to bits 2 days later ~! macgyvering a new gear for it arrrrr :roll: i can give it another go ! I was thinking hell this should be easier little did i know !
Advice from Albert on the mechanical recorder to add external sync is something i am now looking into .
Going off track a bit here but i know it works i found on my past Nipkow PMT camera if the disk speed is correct i don't need any mechanical sync i just use a 400hz crystal clock adjust the pulse width inset mix it back into the video ...nice clean synced video ...
I have this already made just need monostable chip to adjust the pulse width ....So for NBTV this is do able SSTV i could use 50 hz and do the same thing for the cd recorder i would expect then to start seeing at least poor out of sync video...seems an easy solution if it works i will find out ...
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PHILIPS-D-6920-MK2-Portable-Stereo-Cassette-Recorder.jpg
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 Oct 03, 2019 12:39 am

Harry,

before you are going to try to record NBTV, first try to record a square wave signal. If you listen at the replay, you hear almost the same sound as when you listen at the original wave form. But if you look at your oscilloscope to the replay signal, you will not recognize the square wave of the input signal.

This happens because the lower frequencies are recorded deeper in the tape and at some distance from the gap in the recording head. The higher frequencies are recorded on the surface af the tape and right under the gap. What you will see is that the recorded square wave plays back as a more or less triangle wave.

As our ears are not sensitive to wave forms, but sensitive to the volume (strength) of higher and lower sine waves, we do not hear this type of distortion. SSTV is much less sensitive to this, because it is an FM tone. All frequencies are close to each other, 1500 Hz to 2300 Hz, in the audio spectrum. So all tones are recorded at almost the same depth in the tape and at almost the same distance from the gap in the recording head.

This distortion is deadly for NBTV video signals. That is the reason that all video tape recorders work with a FM subcarrier, just like SSTV.

But do not stop your experiments.! Go on with it, because only if you see it yourself, you are convinced and you learnt from it for life time.
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