Mechanical video recorder

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Re: Mechanical video recorder

Postby Klaas Robers » Wed Jan 08, 2020 10:46 pm

And, what is more, it is a stereo amplifier. If you feed-in the input signal in normal polarity for left and upside down polarity for right, you can connect the cartridge between the left and the right outputs. That is called a "bridge" amplifier.

But first measure if the black sockets of the outputs are interconnected to the internal "ground". It is not impossible that the amplifier internaly is already a bridge amplifier, and then this trick does not work. The internal ground can be found on the input sockets.

Good luck.

I see four outputs for speakers. And then I know:
- a 100 watts stereo amplifier, that is 50 watts per channel.
- if you have 4 loudspeaker outputs, that may be 25 watts per output,
- and thus 12.5 watts per channel.

I don't thrust that 4 loudspeaker outputs.....

And who told you that the amplifier was 100 watts?
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Re: Mechanical video recorder

Postby Harry Dalek » Thu Jan 09, 2020 10:37 am

Klaas Robers wrote:And, what is more, it is a stereo amplifier. If you feed-in the input signal in normal polarity for left and upside down polarity for right, you can connect the cartridge between the left and the right outputs. That is called a "bridge" amplifier.


OH i see i do have a stereo cartridge this one was just an old mono ,i have not really looked into stereo yet as i would be getting ahead of my self ,i need to get mono right as far as play back for now ...but your advice is something i didn't think of.

But first measure if the black sockets of the outputs are interconnected to the internal "ground". It is not impossible that the amplifier internaly is already a bridge amplifier, and then this trick does not work. The internal ground can be found on the input sockets.



I will test today let you know mmm very interesting ...this amplifier was just a lucky find 10 dollars i saw the large transformer in side so even if it didn't work it and the case were worth it but it works fine ! i suppose people just don't like big electronics in there house there days ..no problem for me that's in my shed work shop for experiments :wink:

EDIt i tested the black sockets they are not grounded !

Good luck.


Thanks Klaas i want to do a sweep test on the cartridge
edit...i did a sweep test on the newer cartridge no problems to 10khz i don't have a sweep test to 20 but on line found something to 16khz ....the old cartridge seems to go to 9khz the newer one does much better to the higher frequencies i think .

I see four outputs for speakers. And then I know:
- a 100 watts stereo amplifier, that is 50 watts per channel.
- if you have 4 loudspeaker outputs, that may be 25 watts per output,
- and thus 12.5 watts per channel.


Lucky the device is new enough to have a lots of information on the net still i will look if i can find more but have the pdf below
RX-5502.pdf
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I don't thrust that 4 loudspeaker outputs.....

And who told you that the amplifier was 100 watts?


Oh i looked it up i had no idea at first but its in every thing i have seen ...rx 5502 av receiver at power output stereo 100w x 2 20hz 20khz,.
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Re: Mechanical video recorder

Postby Klaas Robers » Thu Jan 09, 2020 9:37 pm

There is nothing wrong with a mono cartridge for your aplication. Keep that, it might even be better than a stereo one.

No, the point is that you can sometimes use a stereo amplifier as a mono amplifier that gives the double output voltage. That is what I wrote about the bridge amplifier. But sometimes each channel of a stereo amplifier is already a bridge amplifier, and then the trick will not run.

I know this trick as NXP has an integrated stereo amplifier chip TDA1519, which contains two amplifiers. It is designed for car-stereo. One amplifier inverts the input signal. In a carradio you want to run the output amplifier on the voltage of 13.8 volt. That limits the output voltage to 13.8 volt peak-peak, 6.9 volt peak. The designer can use the chip as a stereo amplifier, then he should connect one of the speakers in "reverse". But he can also use the chip as a single bridge amplifier by simply joining the two inputs and connect the loudspeaker in between the two outputs. That will give an output voltage of 27.6 volt peak-peak or 13.8 volt peak. And yes, then he will need a second chip for the other channel. I once used this chip as a bridge amplifier, so I know it.

I am still thinking how you could check if your amplifier can be used as a bridge amplifier, or that it will not bring you the extra output voltage.....
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Re: Mechanical video recorder

Postby Harry Dalek » Thu Jan 09, 2020 10:55 pm

Klaas Robers wrote:There is nothing wrong with a mono cartridge for your aplication. Keep that, it might even be better than a stereo one.


Testing the mono i think its bandwidth gos up to 9 khz ,the stereo one i know for sure is still going strong on 10 khz and above ...just hearing the results the stereo one does do better hearing the frequency sweep on the higher end i would say 4 khz up it beats the mono ...but for SSTV i agree the mono would be ok still...
Think the mono stylus is a bit worn which might cause problems on tracking as well as play back ..so love to use it just have to see if it still works as far as the stylus gos .

When i start doing recording again i can check the recording with the scope more accurate than my old ears !

I was mainly interested to see since i only have the ceramic type what would be the result if i used it to do the embossing ,i will be getting a magnetic type as well as i think those would be less power hungry to work .

No, the point is that you can sometimes use a stereo amplifier as a mono amplifier that gives the double output voltage. That is what I wrote about the bridge amplifier. But sometimes each channel of a stereo amplifier is already a bridge amplifier, and then the trick will not run.


OH i see ...

I know this trick as NXP has an integrated stereo amplifier chip TDA1519, which contains two amplifiers. It is designed for car-stereo. One amplifier inverts the input signal. In a carradio you want to run the output amplifier on the voltage of 13.8 volt. That limits the output voltage to 13.8 volt peak-peak, 6.9 volt peak. The designer can use the chip as a stereo amplifier, then he should connect one of the speakers in "reverse". But he can also use the chip as a single bridge amplifier by simply joining the two inputs and connect the loudspeaker in between the two outputs. That will give an output voltage of 27.6 volt peak-peak or 13.8 volt peak. And yes, then he will need a second chip for the other channel. I once used this chip as a bridge amplifier, so I know it.


70 % volume seems fine on the mono 70 to 80% on the stereo cartridge i think there will be distortion running them much higher .

I am still thinking how you could check if your amplifier can be used as a bridge amplifier, or that it will not bring you the extra output voltage.....


I could i suppose try both L R input channels and outputs left right to cartridge same result to either side of the cartridge ,you would think you would need half the amount of volume to drive it then ...but its not a problem at all for a recording as is it would work now just with that one channel .

I still have a bit of work on play back placing play back arm and for correct tracking ,bit limited to placement of it but i will have to do some play back tests to see all is fine here before moving on ...

Edit ....having played around with the 2 tone play back arms from the 50s i am not very happy with them due to their mechanical construction on the the 2 pivot points i think i can do better , i also need this to be more adjustable to the new play back area on the case ..pretty much worked out what i will use a old broken lap top HD and again here a voice coil arm from and older HD these will give me finer movements in the two axis movements the arm idea so far is a metal drinking straw need some thing hollow to carry the wires from the stylus cartridge ....so thats what i am up to .
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The Tone Arm

Postby Harry Dalek » Fri Jan 10, 2020 5:10 pm

This afternoon i had some spare time 4 hours later i knocked together the idea i had in the morning ,i still have to mount the stylus cartridge and balance the arm with some weight at the back .
Attachments
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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 » Sat Jan 11, 2020 6:55 pm

Today i hooked up the amplifier and just bolted the past ceramic cartridge to the DIY tone arm and gave it a run its a touch to long with the bolted on attachment but bit of positioning got it to play very happy with the tone arm .
DSCN9987.JPG

Below i started off testing an old 78 rpm record first time have heard this turntable play any thing



Next i tried a prerecorded sstv from the last lathe the arm tracks and cartridge plays so getting there .



Its pretty much nearly there i just have to think about plugs and such to input out put signals

I am going to buy a Turntable Headshell Mount as below neaten up the cartridge area... idea is to be able to exchange ceramic and magnetic heads i will use the 100 watt amplifier on a ceramic head for testing ...any case but switching and sockets for plugs need to be mounted next .
Looking at the play back heads on the new cartridges the stylus is a bit weakly attached unlike the vintage it might need it Mcguyered a touch to make it stiffer for embossing speculating .
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Attachments
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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 » Sun Jan 12, 2020 3:42 pm

I looked into the input outputting signals problem today and went with RCA sockets which i will use with some switching ...i stopped here having a think what i want to attach need to list it before firing up the solder iron again and cutting the cables .

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I also put in a new power switch and lengthened the switch wiring i had it to short hard to work on the insides which was a problem .... now much better .

DSCN9997.JPG


Also need a clean up the mess ....!
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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 Klaas Robers » Sun Jan 12, 2020 10:34 pm

I think that for cutting, the monocartridge is better than the stereo cartridge. In a stereo cartridge the "needle" should have vertical movement too, and for cutting you need a much larger needle pressure. A mono cartridge can bear that much better than a stereo cartridge.

Then I observed that playing back the 78 rpm record, there was a lack of low tones. I experienced that when I played back a 78 rpm record with the proper low up and high down characteristic that the sound reproduction is quite good. But if you played back using a small loudspeaker, then this could also be the manco.

The SSTV-play back was sounding quit well..... However I did not try to feed it into my SSTV monitor.
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Re: Mechanical video recorder

Postby Harry Dalek » Mon Jan 13, 2020 9:11 pm

Klaas Robers wrote:I think that for cutting, the monocartridge is better than the stereo cartridge.


Oh for sure the old mono is much stronger ...only from a quick test it has a lower bandwidth

In a stereo cartridge the "needle" should have vertical movement too, and for cutting you need a much larger needle pressure. A mono cartridge can bear that much better than a stereo cartridge.


I had not really bothered to look closely at one but they are more feeble than the vintage cartridges..i am for the first attempt reusing my DIY embossing head .

Then I observed that playing back the 78 rpm record, there was a lack of low tones. I experienced that when I played back a 78 rpm record with the proper low up and high down characteristic that the sound reproduction is quite good. But if you played back using a small loudspeaker, then this could also be the manco.


And pretty much yes and bad mounting position due to the room problem in the case ,i use have that only that i can hear the play back in some form more than perfect i suppose i could output a connection for a speaker .

The SSTV-play back was sounding quit well..... However I did not try to feed it into my SSTV monitor.


No not yet Klaas i want to finish off the cabling and do a new recording but it will be interesting to also see how the older other lathe recording plays back like ..i will do this later in the week just ran out of time .
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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Testing Mechanical video recorder MK2

Postby Harry Dalek » Sat Jan 18, 2020 6:10 pm

First chance to get back to this today so hooked up MK2 and gave it a record.

Below is the first image i have tried to record in 8 sec SSTV ...and oh no i still have the dreaded syncing problem.... :shock:

Better than i would of expected took 100 or more cds to get any where near this stage the first time around .

At first i was thinking it might be worn roller but didn't seem likely from what Klaas mentioned a while back ....did a record at 45 rpm has shown the same result apart from the image is poorer so i think it has nothing to do with this and comes down to the slight amount of fiction which is more for embossing the video on the cd than playing back and makes sense and when played back the video is running faster you have to slow down the platter to get it sync .

So there is a solution ... i was testing today ...thank goodness ~!

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Some more tests below i was looking into fiction at first just to see how much speed reduction i needed before moving on to the idea i want to build into this
.
Below the image used for the next recording test

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With a slight amount of fiction to the platter i can get the image to display

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Now i know what the problem is i started to experiment with eddy current braking using a hard drive neodymium magnet bit closer than shown !

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I could see its giving a similar effect to fiction braking but in this case distance kept stable next to the platter very hard to keep one of these magnets steady at about 10 mm ,i need to experiment more on this needs to be a screw adjustment to adjust the magnets distance ,i will have think about it .
Bit of noise in the last two images i need to earth the amplifier
And i tried earlier also 36 second SSTV i found it did record and start up on the VIS code every time ...8 sec bit hit or miss not sure why
Attachments
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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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What to do next ?

Postby Harry Dalek » Sun Jan 19, 2020 4:38 pm

I mounted the magnetic for some sort speed correction better than nothing , it really should be a screw driver adjustment as it can be that that tight .but its all i have handy to correct the speed for now .
Below the mounted magnet i remove when recording
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The result is ok still not perfect least its mostly in sync ,the video is a you tube 8 sec SSTV wav don't think it uses the VIS code



Below image 8 sec SSTV recorded of cause

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I wanted to test other video formats and i found that any thing that runs slower than 8 sec SSTV is harder to sync ,had a go at 36 sec colour for the hell it... and this was the best i could get out today ......below image was just a colour bar ,i was adjusting the magnet during this image magnetic distance from platter was very tight...

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Attachments
DSCN9868_x264.mp4
(20.04 MiB) Downloaded 13 times
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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