VCR Head rotating a device

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VCR Head rotating a device

Postby Harry Dalek » Fri Sep 11, 2015 10:35 pm

I have a few junked vcr heads never really used them much apart from knowing they are well machined mechanically always found cd dvd motors and hard drive ones more to my liking due to size .

Looking into some ideas into the problem of rotating an on board led or light sensor the light sensor interests me a bit more but if worked out can take projects to another direction literally.

Powering every thing rotating and transfering data ,i hate the idea of slip rings but this DIY rotating slip ring using ballbearings seems good (first photo} and from this site
http://stephanschulz.ca/sts/howto/slipring.html

Any case may be ok for powering but i bet they are all noisy for any signal transfer.

Powering the rotating led light or sensor via the VCRs rotary transformer sounds good ,looking into this i have seen 2 examples of using the head for this so far ...

http://us.cactii.net/~bb/propclock/index.html

This explanation from this rotating display[color=#FF4000]

In the base of the clock, a simple 555 based oscillator switches a power MOSFET at 100KHz, energising the rotary transformer's primary. The signal induced into the secondary is rectified by an FR104 fast recovery diode, then filtered and regulated down to 5 volts. I am able to get the necessary current to run the clock with this. I initially feared that there would be a lot of noise interfering with the micro, but this turns out not to be a problem.


Also looks to me like this fellow on you tube used the same idea to use a 555 timer and mosfet to get 5 volts out of the secondary roatary transformer winding but i think its in spanish viewing guessing only for me :shock:
https://www.youtube.com/watch?v=_W_AB17pNp0

https://www.youtube.com/watch?v=lFMDQaXvGA4

Second photo and video it seems to get enough voltage for any little rotating circuit .

I haven't tried this my self but looks like a nice solution to powering a rotating circuit .

The rotary transformer i suppose has more than one winding and could be used one way or another for other signals in or out ...but you could by pass this and use a magnetic optical or even ultrasonic in the case of low bandwidth sstv ....placing the sensor top middle of the vcr head would not matter if its rotating or not they would always be lined up ...

Driving the VCR motor its self would make it neat ,i noticed Steve has a design in a a past newsletter but you could always belt drive the thing.
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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: VCR Head rotating a device

Postby Harry Dalek » Fri Sep 18, 2015 5:25 pm

Using a vcr head as a test bed to experment on an idea i have been thinking about for a while and give it a try between every thing else i am upto ...

I have the vcr head mounted with a dc motor to turn it with a pulley , i could use the motor on the head but to speed work up i will use this for now cut down on some electronics..

I am thinking again on 7 8 sec or 12 sec SSTV side of things to use the vcr head to rotate 4 light sensors for the line frequncey i am not worring about frame for now as with the last go i did all you need to do is move something slowly infront of it to see a image result ,so if it shows promise i will worry about that then .

Interested to see what a direct approach has to replacing mirrors ,only problem being its so much more complex rotating a head amp,i always found mirrors fine for the monitor side but a lot harder for camera ideas may be its just me :oops:

I should be able to using the rotary transformer for the power supply and have a choice of magnetic ultrasonic or light to transfer the FM Slow scan .

I also see the problem of switching the light sensors or light sensors with its own headamp so the one doing the line scan is on and the other 3 are switched off ...I was thinking at first just use a mask and hooking all 4 light sensors up to one head amp 3 will be in darkness while one has a light slot, i suppose you use what works .

Lots of problems to work on
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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: VCR Head rotating a device

Postby Harry Dalek » Thu Sep 24, 2015 8:48 pm

I have been trying my circuits out on the vcr rotary transformer today .

Started off with half a volt out of the thing and a few hours later i have about 5 volts by this afternoon with a single diode and cap.

I made 2 oscillator circuits the 555 i am having problems with the coil drive transistor or i am way off frequency to drive the primary coil ,the one that works i am using here is a 4060 crystal oscillator and seems to work best at 44khz ,i want to get the 555 going so i can check which is the best resonating frequency to use that i can produce i suspect at best it should be at what the video heads once worked at in the MHZ range but i am happy with 5 volts .

I have to run my primary coil driver transistor at about 12 volts to get 5 volts out of the rotary transformers secondary so its a bit lossy still we are talking only a few turns of wire on both primary and secondary .

I can put it back together now for more work .
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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: VCR Head rotating a device

Postby Harry Dalek » Fri Sep 25, 2015 9:18 pm

Spent a bit more time on this today ...

Got the second 555 oscillator to work with the VCR head rotary transformer but results were not what i was expecting ,got it to work from 6 to 200 khz seemed to work best again around 40 to 50 khz where voltage out the secondary seemed best ,even adjusting the pulse width only got a volt more but aging results where not as good as the crystal circuit yet any way .

Any case wired it together and remounted the vcr head and mounted some circuit boards which will be rotating and powered from the rotary transformer ,tried my constructed head amp and voltage controlled oscillator and seems to power up fine with from the transformers supply .

The rough plan i hope it will work :roll: bottom circuit board will be the power supply board diodes caps regulator ,top board so far the head amps and or with VCO's .
I want to switch the the scan area on and have the other 3 off so need a switching circuit for this as well and something to transmit it off the rotating boards output may be an IR led as i said before there's other options.....see how it go's step by step
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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: VCR Head rotating a device

Postby Harry Dalek » Sun Sep 27, 2015 9:26 pm

The power supply seems nice and clean but a slight drop down in voltage which i noticed from my regulator while testing a off board head amp and vco ,i have a few more circuits to at to my rotating tower so need to keep an eye on this .

I need next to see if my cabled light sensors work with the ready made circuit and do a slow rotation.

Been thinking about the switching of the light sensor head amps on and off for the scanning area and i will use a optical switch 4017 count to 4 and a 4066 for the switching might be able to get away with just using one VCO .
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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: VCR Head rotating a device

Postby Harry Dalek » Fri Oct 02, 2015 7:40 pm

I spent the day fixing a short with the light sensors i took a little amount off the bottom video head casing to fix this intermittent short mechanical problem .

After this i have started on the 4 head amps .

Uploaded my Scribblings block diagram as i go here :shock: .....basic ideas to work out a switching rotating of 4 head amps i think might work

I have swapped the ic to switch the 4066 and now going to try a 74194 works fine for the stepper motor circuits and i have this handy .

Have not really looked into the motor control side of it yet ,just need to see if the switching of the audio part of it works .
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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: VCR Head rotating a device

Postby Harry Dalek » Sat Oct 03, 2015 8:04 pm

I was working on the opto switch part of it today got half of it done ,the opto switch has to be rotating due to the electronics have to as well so the light breakers are stationary.\

Lucky it doesn't have to spin to fast with all that hanging off it at uncontrolled speeds there is vibration she'd be no good for NBTV .

I would like to see the difference using this sensor rotating as to the rotating reflection i tried before so hope it works ,lots more to work out .
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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: VCR Head rotating a device

Postby Harry Dalek » Wed Oct 07, 2015 9:26 pm

I have been rethinking the opto switch idea on the stationary side of things to neaten it up not happy with the constructed idea ,it will not take much for the 4 sides to be off a bit and every 4 lines will be jagged so i needed a accurate square big enough for the job and don't have to make ......and what looks like what might work is reusing a PC power supply fan with the fan part taken out it'll fit right over the vcr drum ,being 4 sided can adjust it all at once for the opto switch .

Placement of the rotating opto switch will be changed a bit now.
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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: VCR Head rotating a device

Postby Harry Dalek » Sun Oct 25, 2015 7:22 pm

Been working on a few things of late and getting this to the point of being happy with the mechanical switching or how it should work i think i can more on to the circuits again .

I have used the fan casing the bolts on the 4 corners brake the light on the opto switch ,had to angle it a bit for a try as the bolts are a touch short if the opto switch is dead horizontal /

I can change the position on the start of the pulse just moving the fan casing.
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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: VCR Head rotating a device

Postby AncientBrit » Tue Nov 03, 2015 1:09 am

Hi Harry,

Just out of interest I purchased a pair of ball bearings but on measuring the resistance between inner and outer cages I was very disappointed, of the order of 10's of ohms, which changed as the shaft rotated.
So I don't think that's a solution for power transfer, let alone signal transfer.

Cheers,

Graham
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Re: VCR Head rotating a device

Postby Harry Dalek » Tue Nov 03, 2015 8:32 pm

AncientBrit wrote:Hi Harry,

Just out of interest I purchased a pair of ball bearings but on measuring the resistance between inner and outer cages I was very disappointed, of the order of 10's of ohms, which changed as the shaft rotated.
So I don't think that's a solution for power transfer, let alone signal transfer.

Cheers,

Graham



Hi Graham
I am using the rotary transformer power only ,could of just used one of those flat phone batteries and save a lot of work but i was curious and wanted to try it .

Not really using the case at all for any slip ring ball bearings idea ...i was thinking of that before i did some tests as you have on the ball bearing so i gave that idea up ~!

What i plan is as now its powered as it rotates i want it to switch the light detection area on and the other 3 areas off ...its slow scan so feed the head amp to a 4066 which will be switched on via that opto switch and its count to 4 circuit then to pass the audio to feed a VCO 4046 then i need to modulate say a led that points up top in the middle of the rotating head .....light sensor receiver pointing down above it to pick up the FM modulated light ....every thing should line up that way ...feed that to my laptop with a sstv program and hope i see something recognisable if i hand scan some thing in front of it, or just place a gray bar test card in front as the lines will repeat.
So signal transfer i plan to transmit via light no wires
At the moment i am playing around with the 3bp1 CRT but i will get back to it some times i need to go off on another direction like Mr Bean ! :wink:
Last edited by Harry Dalek on Tue Nov 03, 2015 10:38 pm, edited 1 time in total.
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: VCR Head rotating a device

Postby AncientBrit » Tue Nov 03, 2015 9:29 pm

Hi Harry,

As you may gather I am following the various threads that you and Steve A have running currently.

Very interesting work you are doing across a range of ideas.
Keep it up!

Cheers,

Graham
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Re: VCR Head rotating a device

Postby SholomPei » Tue Dec 15, 2015 2:35 am

Can you please tell me what are the required components to do this?
I mean how you are running the device by VCR head?
What system you are using, please tell its full specifications?
Also is there any special head required?
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Re: VCR Head rotating a device

Postby Harry Dalek » Sun Dec 20, 2015 3:13 pm

SholomPei wrote:Can you please tell me what are the required components to do this?
I mean how you are running the device by VCR head?
What system you are using, please tell its full specifications?
Also is there any special head required?


You could use the vcr head motor but i am at the moment using a dc but i think when i get back to this i will swap it with a stepper motor ....this would be even better i was able to get very little drift when i tried with the sstv scanning device i made a while back..i would stick with a stepper motor you can run it in manual control with little adjustment at all once your at the correct speed you see this as the start and end lines sync up together but i would use a pulley system for different speeds you can do 12 sec slow scan as well.
viewtopic.php?f=8&t=1890&start=120
I had trouble with reflecting mirrors to a stationary sensor reason of trying it the other way around here .
full specifications are not there yet as it a work in progress i have mentioned the idea and what i plan to use a post or 2 back as in its sort of really a rotating version of the sstv scanning device and having to deal with powering the rotating circuits and getting the video out with out wires so that would be done with a Led transmitting above the middle of the drum and having a sensor receive it located above it could do it other ways least power wasted this way
You might beat me to it as i am building a monitor at the moment very hard to multi task :roll:
I used the drums rotary transformer for powering it but you could just use battery .....
I just used this head because it had 4 heads with only 2 the scan would be very wide and also more sensors less speed needed easier it is to control speed wise it also gave me a place to mount the sensors without having to line them up ...if any of the lines are off every other line will be a bit off in a 4 line movement so lining them up is similar to a problem of lining up mirrors .
You have to make some thing like this in stages as so many things need to work same time problems ....vibration due to the boards is another ..if it works or not the fun is trying.
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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