2 motors in sync Question

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2 motors in sync Question

Postby Harry Dalek » Sat Aug 27, 2016 11:57 am

I have been reading up on camera monitors using Nipkow's with either a second spiral or a second disc using same motor shaft for syncing the easy way ....
I was wondering if you had 2 of the same motor connected them in perhaps either series or parallel if the first motor was position controlled as per norm with feed back club circuit such would the second motor pretty much be in sync tied electrically to the other ? just something i was thinking about.
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Re: 2 motors in sync Question

Postby Panrock » Sat Aug 27, 2016 5:22 pm

Interesting.

When your "first" motor was synched though, wouldn't this have to be to a third "master" motor, to give the circuit a comparison reference? Only then could its spiky correction waveform be generated.

After that though, you could sync to any number of motors at once, in series or parallel, given enough power from the sync output circuit and appropriate drive voltage and current.

Steve O

PS. If you simply joined exactly similar commutator-type motors in series across a DC supply, I reckon there would be a sync effect too.
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Re: 2 motors in sync Question

Postby Harry Dalek » Sat Aug 27, 2016 8:52 pm

Panrock wrote:Interesting.

When your "first" motor was synched though, wouldn't this have to be to a third "master" motor, to give the circuit a comparison reference? Only then could its spiky correction waveform be generated.

After that though, you could sync to any number of motors at once, in series or parallel, given enough power from the sync output circuit and appropriate drive voltage and current.

Steve O

PS. If you simply joined exactly similar commutator-type motors in series across a DC supply, I reckon there would be a sync effect too.



I was thinking DC commutator type motors when thinking about this .
The problem i was wondering about was Nipkow disc as a camera and monitor it must be hard stopping the small amount of monitor light getting to the camera side there has to be a gap between the disk and light barrier between two .
Thinking it would be nice to keep the camera monitor idea in a separate enclosure with the easy same syncing idea as a same disc or shaft but do it with wire without another control circuit .
I have no idea really never tried it ,Steve just a hunch in that it must be logical two of the same motors would run at the same speed so long as one is feed back controlled useful for NBTV.
It would make a mechanical camera a little more versatile as to where you wanted the monitor mounted .
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Re: 2 motors in sync Question

Postby Klaas Robers » Tue Aug 30, 2016 6:45 am

Harry, somewhere on this forum is a description of an Australian man, who made a monitor and a camera on the same axle. So two Nipkow discs on one long spindle and with one motor. In that case there is no synchronisation problem. He made this for an Australian exhibition or museum demonstrator. In between the two discs he had a replica valve amplifier as a video amplifier. And indeed there were two enclosures, one for the "camera", the other for the monitor.

Would this idea help you? In any case you can apply your PMTs in this way.
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Re: 2 motors in sync Question

Postby Harry Dalek » Tue Aug 30, 2016 6:38 pm

Klaas Robers wrote:Harry, somewhere on this forum is a description of an Australian man, who made a monitor and a camera on the same axle. So two Nipkow discs on one long spindle and with one motor. In that case there is no synchronisation problem. He made this for an Australian exhibition or museum demonstrator. In between the two discs he had a replica valve amplifier as a video amplifier. And indeed there were two enclosures, one for the "camera", the other for the monitor.

Would this idea help you? In any case you can apply your PMTs in this way.


Hi Klaas
Yes i know of The late Gil Miles
viewtopic.php?f=1&t=1906&hilit=gil+miles
Syncing this way is an elegant for sure along with the using the same nipkow 1.5 spiral which would be easiest way
I was interested in if 2 of the same make dc motors hooked up to each other would rotate in sync with each other if that worked if one motor were feed back controlled the other should follow (perhaps :roll: ) ,i have not really come across this talked about ,i suppose only way to really know is try it some time .
But yes for sure i am thinking about using the PMT on a Nipkow in a traditional way i need all the help i can get !
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Re: 2 motors in sync Question

Postby Klaas Robers » Wed Aug 31, 2016 7:09 am

No Harry, two DC-motors circuited in series will not sync at all. The rotation speed is proportional to the voltage, the given torque is proportional to the current. With two motors in series they behave lik a differential drive of a car. if you brake one motor gently the other speeds up.

Two identical motors circuited in parallel run (almost) the same speed. But it is almost as the ohmic resistance of the copper windings give the deviation. So no real synchronisation in this too simple way.
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Re: 2 motors in sync Question

Postby Harry Dalek » Wed Aug 31, 2016 5:21 pm

Klaas Robers wrote:No Harry, two DC-motors circuited in series will not sync at all. The rotation speed is proportional to the voltage, the given torque is proportional to the current. With two motors in series they behave lik a differential drive of a car. if you brake one motor gently the other speeds up.

Two identical motors circuited in parallel run (almost) the same speed. But it is almost as the ohmic resistance of the copper windings give the deviation. So no real synchronisation in this too simple way.


HI Klaas

Well even with stepper motors staying at a constant speed without rotation feed back they do drift slowly.

What about 2 same make motors one with feed back control the other same make motor in parallel with this motor it would be getting the same control voltage as the first ?
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Re: 2 motors in sync Question

Postby Klaas Robers » Wed Aug 31, 2016 10:11 pm

Yes, it will. However all disturbances due to differences in temperature, air movements or whatever, will cause the second motor to slow down or speed up somewhat. And for a Nipkow disc it is not the speed that is essential, it is the fine coinciding position at every moment in time. That is the reason that I suggested the long spindle. Then the position is granted every moment in time.

That is what I should try first to get running. And then, when that runs satisfactory, you might think of an electronic extension of the spindle, that is stiff enough to meet your demands.
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Re: 2 motors in sync Question

Postby Harry Dalek » Thu Sep 01, 2016 8:35 pm

Klaas Robers wrote:Yes, it will. However all disturbances due to differences in temperature, air movements or whatever, will cause the second motor to slow down or speed up somewhat. And for a Nipkow disc it is not the speed that is essential, it is the fine coinciding position at every moment in time. That is the reason that I suggested the long spindle. Then the position is granted every moment in time.

That is what I should try first to get running. And then, when that runs satisfactory, you might think of an electronic extension of the spindle, that is stiff enough to meet your demands.


No worries Klaas well that idea has gone down like the titanic.... :wink:

I would try a traditional simple way to use with the PMT ,to start off with ,have not had much time to my self to get things done apart from ask questions and plan ,i think i will use a round biscuit tin for the nipkow light proof case ,so getting a few things together and seeing if there will be any problems before i start to tack things together .
I like the 1.5 spiral idea for a monitor but bit worried how well the modulated leds light might get over to the PMT side ... i am thinking the idea may well be ok for a less sensitive light sensor like solar cell or photo transistor but the pmt mmmm
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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