NBTV Camera Question

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Postby Harry Dalek » Fri May 04, 2012 12:39 pm

gary wrote:
harry dalek wrote:t ..let you know how i go .


The birth of a new machine - can't wait! :-)


Doing the monitor part sort have doubled the work ,i was at first thinking ok i would be happy to have a visual indicator at the right 750rpm speed not really worry about the picture that much ,but it bothered me ....side tracked again least its on the same project this time .

I am not sure if this is the case for sure but it seems to me harder controlling a smaller disk and a large ,PWM helps ...

I am now thinking of an op amp between the light sensor circuit and the monitor,i don't think the sensor circuit has the levels to drive the monitor circuit ..

I would just have to output the sensors signal to the pc sound card as is i suppose ,i will start looking for that sync printout ,looking into it doesn't look that hard to mix sync pulse with the video any case i will find out in time . :roll:
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Postby gary » Fri May 04, 2012 12:49 pm

harry dalek wrote:looking into it doesn't look that hard to mix sync pulse with the video any case i will find out in time . :roll:


Harry, I STRONGLY recommend you place the sync pulses, by themselves, on what is normally used for the audio channel, i.e. the right hand channel, to begin with - that way you can concentrate on tweaking the picture stuff. I can give you software to display the picture in real time, also to mix the sync into the picture to make it NBTVA compatible.

You can add the circuitry to mix the synch in later.
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Postby Harry Dalek » Fri May 04, 2012 1:55 pm

gary wrote:
harry dalek wrote:looking into it doesn't look that hard to mix sync pulse with the video any case i will find out in time . :roll:


Harry, I STRONGLY recommend you place the sync pulses, by themselves, on what is normally used for the audio channel, i.e. the right hand channel, to begin with - that way you can concentrate on tweaking the picture stuff. I can give you software to display the picture in real time, also to mix the sync into the picture to make it NBTVA compatible.

You can add the circuitry to mix the synch in later.


I have listened ! i suppose thats easier for a start best to evolve into it ,and was wondering about the tweaking side of it .
Yes the later would be very helpful...have to look at your photo of your project again did you just use holes in the disk for your sync.
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Postby gary » Fri May 04, 2012 2:17 pm

No, I never use holes for sync anymore - I use the encoder (as used on the MUTR televisor)

http://www.taswegian.com/NBTV/forum/dow ... hp?id=1877

with the reflective sensor (the one I sent you) - much much easier to add and change if necessary.
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Postby gary » Fri May 04, 2012 2:49 pm

I usually attach it to the back of the disk, but sometimes it is easier to add it to the front.
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Postby Harry Dalek » Sat May 05, 2012 12:24 am

gary wrote:I usually attach it to the back of the disk, but sometimes it is easier to add it to the front.


Reading the old thread on the MUTR televisor it sounds like the disk would be better movable till you find the correct position ?.

i think i will have it on the back more to mount a sensor.

I made a little IC amplifier that will hopefully be enough to drive my luxeon circuit today i just really have to hook it up to my solar cell dome sensor circuit and see what happens.

if all gos well i will work on the sync disk and sensor + circuit next/
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Postby gary » Sat May 05, 2012 8:36 am

harry dalek wrote:Reading the old thread on the MUTR televisor it sounds like the disk would be better movable till you find the correct position ?.


Probably, although it's generally good enough to just align the "missing" bits - i.e. the missing aperture and the missing encoder segment.

If you use that craft glue spray on the back of the encoder and let it go "tacky" for 5 minutes it holds on to the disk well but remains removable if it needs to be adjusted - there are probably cleverer ways of doing it, and, of course an even better, but more complicated way is to make the sensor position adjustable.

In truth, for my purposes, the position really doesn't matter that much because it is the speed measurement my time base correction software requires not the framing - that can always be determined later.
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Postby Harry Dalek » Sat May 05, 2012 2:34 pm

gary wrote:
harry dalek wrote:Reading the old thread on the MUTR televisor it sounds like the disk would be better movable till you find the correct position ?.


Probably, although it's generally good enough to just align the "missing" bits - i.e. the missing aperture and the missing encoder segment.

If you use that craft glue spray on the back of the encoder and let it go "tacky" for 5 minutes it holds on to the disk well but remains removable if it needs to be adjusted - there are probably cleverer ways of doing it, and, of course an even better, but more complicated way is to make the sensor position adjustable.

In truth, for my purposes, the position really doesn't matter that much because it is the speed measurement my time base correction software requires not the framing - that can always be determined later.



Ok Gary i didn't think of moving the sensor...i was thinking more the lining up of the nipkow hole to some where on either the white or black part of the strobe disk...i am a bit ify on this part if it matters at all white back or start middle end of the small stripes matters where it lines up .

Today i work on finishing off the light sensor box with plugs to hook the thing up to my amp and the pc .
Attachments
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Picture 32009.jpg
finished dome sensor
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Postby gary » Sat May 05, 2012 4:00 pm

harry dalek wrote:i was thinking more the lining up of the nipkow hole to some where on either the white or black part of the strobe disk...i am a bit ify on this part if it matters at all white back or start middle end of the small stripes matters where it lines up.


Well to some extent it depends on how you interpret the pulse, but generally you just line up the two missing pulses, or I suppose it's the same thing to say you line up the 31 black segments with the 31 holes...


re video:

heh heh heh, it's one thing to stick your great mitt in front of the sensor in broad daylight - quite another to pick up that tiny twinkling light of the FSS - but you'll soon see ;-) But at least it is responding to light and that's promising.

BTW is one of those sensors still an LDR? (I suppose it must be).
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Postby Harry Dalek » Sat May 05, 2012 10:58 pm

gary wrote:
harry dalek wrote:i was thinking more the lining up of the nipkow hole to some where on either the white or black part of the strobe disk...i am a bit ify on this part if it matters at all white back or start middle end of the small stripes matters where it lines up.


Well to some extent it depends on how you interpret the pulse, but generally you just line up the two missing pulses, or I suppose it's the same thing to say you line up the 31 black segments with the 31 holes...


re video:

heh heh heh, it's one thing to stick your great mitt in front of the sensor in broad daylight - quite another to pick up that tiny twinkling light of the FSS - but you'll soon see ;-) But at least it is responding to light and that's promising.

BTW is one of those sensors still an LDR? (I suppose it must be).



I will have to work that out on the strobe disk thing when i do it i suppose the size of the print out will give you the pulse width size to ...but sounds like need to match them to where the holes are in the disk from our chatting .

Yes the second one is now a LRD i made the first stage amp in that case for it to now,i ran out of room to do any more electronics to amplify that more ,i just want to finish that off for now so i can close the case for good .

I am pretty happy with the light sensor that was pointed at a darker hall way its just picking up the tv from the side with some some pulses seen yes i expect low levels so i will try it in a dark or darkend room it ,gos bonkers when you point it at the tv across the room.,but as you say thats not a dim nipkow scan .
i think its hopeful if thats the only light in the room for a start it may work seems pretty sensitive .
I can see with my lens system closer for farer away focusing this will help with light level as well ....but size wise just depends what i can try and scan ....close gives a small scan area but lighter far larger and dimmer .
I will start doing some scan tests with the disk see if my sensor can pick up any of the nipkow light so perhaps time to do some trials .
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Postby gary » Sat May 05, 2012 11:45 pm

No need to get too fussy with the phasing of the encoder at this stage, it's just the speed that's important for a picture to be obtained, once that's done you can finesse it all you want.
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Postby Harry Dalek » Tue May 08, 2012 5:13 pm

gary wrote:No need to get too fussy with the phasing of the encoder at this stage, it's just the speed that's important for a picture to be obtained, once that's done you can finesse it all you want.


Hi Gary had to remove that plug in my light sensor box and solder the wire to the plug connector ,the plug was disconnecting every time i screwed the box together ....bit of a problem ! but all working now ...slowed me down trying to do those nipkow light tests..

fingers crossed its sensitive enough....so i am still at this step the last should be easy with the sync part if it can pass this test ,and sorry for the late reply !
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Postby Harry Dalek » Thu May 10, 2012 12:53 am

It looks like the light sensor is sensitive enough so long as the reflected image is reflected back to the sensor so angles and such seems very important but so long as it hits the sensor looks like i can do something with that ...its for me no good just to point it ahead .

I am thinking i need a lens in front of the sensor to focus the light to it like gary was saying some time back with the flat bed projector lens...but i think i can use a lens magnifying glass to do the same so all the projected area hits the lens and is directed to the dome sensors area.

So another little redesign knowing this now .

i was trying to take a video of it here its very dark sorry but you can see when light is reflected back to the dome sensor the signal is there looks clean to,only thing i think its just part of the nipkow scan .
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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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Postby Harry Dalek » Thu May 10, 2012 2:24 pm

I have got to the point i need to do some thing with my circuit boards as the wiring is getting messy ,i am going to connect the camera monitor to this case via a 8 pin plug and a audio plug for the video that'll make it a little less messy and have a bit more control other than with my tiny screw driver .
So i have a bit of work today !
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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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Postby Harry Dalek » Sat May 12, 2012 4:56 pm

I have stepped back a bit been working controlling the camera and monitor part from a case .
Just about finished that just have to relocate the monitor controls to this .
I still have to make a tiny mask so only one hole from the nipkow is used at a time and the sync strobe disk needs to be pasted on plus the circuit for that needs to be made.
I also have not tested yet if i have enough amplification for the camera to drive the monitor part /
Not sure if i can record a syncless video i suppose baird did it ?as i can just plug that in to the pc when ever now.
As you see i have relocated the light sensor box and have added a lens which is a giant version of the one used on the sensor which i hope does the same thing but amplified ,its at a distance where the sensor fills all the lens area ,i also have a bit more the azimuth and elevation control of it if need be .So i hope it sees more area than the tiny sensor does .
I suppose also an easier way would be just to use a larger solar cell panel
I think the dome sensor is just a more efficient solar cell for its size ...
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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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