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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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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Harry Dalek
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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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Harry Dalek
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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 ...
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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Harry Dalek
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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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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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4043
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

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