Photomultiplier Tubes camera build

[Harry Dalek]

The 47k at the emitter of the opto transistor is set to 13.3k
The probe when plugged into the computer mic jack is 170.8K
When probe is connected at the opto test point i get 12.52k

I suppose i could drop the 47k trimmer to 12.52 and see at the sync mixer if that causes the wanted speed to control ....with out the probe in place /

If that does not work i am baffled

[Harry Dalek]

Ok i dropped the 47k timmer on the opto trany emitter to 12.50k closest i could get with this trimmer to my last reading with the probe connected ...and it seems to work ....well so far .
I know i peaked the sine wave with the probe connected here at that resistance so i think that is happening now changing that resistance without the probe connected .

BTW Gary i did try the capacitor trimmer on the crystal clock at the time i worked out that probe problem ...any way the picture does slow down on the roll but i still only get a stationary picture around the same place in the video then the slow roll starts again .

[gary]

i still only get a stationary picture around the same place in the video .

What do you mean "around the same place in the video"?

[Harry Dalek]

i still only get a stationary picture around the same place in the video .

What do you mean "around the same place in the video"?

theres a few frames it just locks and then gos its merry way on a roll again same spot ...i don''t know why its not random Gary

[gary]

theres a few frames it just locks and then gos its merry way on a roll again same spot ...i don''t know why its not random Gary

So you are still in monitor mode and it locks at a certain place in the video but not anywhere else?

What if you use a different video?

[Harry Dalek]

theres a few frames it just locks and then gos its merry way on a roll again same spot ...i don''t know why its not random Gary

So you are still in monitor mode and it locks at a certain place in the video but not anywhere else?

What if you use a different video?

Yes still on the monitor mode just as you said either way i need motor control so have not gone back to camera yet .

Is there a video you would like me to try ? i tried that BBC test card girl and slow roll may be the cap or trimmer on the crystal oscillator fixed needs adjusting changing ..

The lock and roll in the video with the different test cards all in a row is something i don't understand .
IT locks on the fade blank part of the video and around the bbc eye for a bit

[gary]

Well that is most interesting since you aren't using the video's syncs for locking - I can't imagine how the video signal could be affecting speed control unless you have some cross talk somewhere and even then it's hard to see how that would have that effect.

I can only suggest trying different videos with different material to see if there is any pattern to it.

Do you have the club CD 3 - any of those would be fine - otherwise just use Video2NBTV to create some random NBTV from whatever movies or pictures you have.

I have to hit the sack now as I have an early start in the morning but I will check in to see if you have any more information. Cheers.

[Klaas Robers]

Harry, what you describe sounds to me as parasitic oscillation.

- Take some metal object, e.g. a small fully metal screw driver, or a piece of bare copper wire
- and touch the input pins of the LM311 with it.
- Yes, you have the screw driver in your hand, so it is also connected to you.
- Look what happens with the rolling.
- If it stops if you touch a certain point, one of the inputs of the LM311,
- then solder a small capacitor, e.g. 220 pF, to that point,
- the other wire to ground.

Yes indeed, this looks as magic, some people do this with a wetted finger in stead of the screwdriver and this also known as "the wet finger method".

The capacity of the oscilloscope probe does the same as the capacity of your body or the 220 pF.

[Harry Dalek]

Well that is most interesting since you aren't using the video's syncs for locking - I can't imagine how the video signal could be affecting speed control unless you have some cross talk somewhere and even then it's hard to see how that would have that effect.

I didn't think it was i was thinking more coincidental syncing with the clock as it the video starts at same time so may be the same point in the video it lines up with my clock /////perhaps just speculating.

I can only suggest trying different videos with different material to see if there is any pattern to it.

OK with the bbc test card Girl its just a slow roll .

Do you have the club CD 3 - any of those would be fine - otherwise just use Video2NBTV to create some random NBTV from whatever movies or pictures you have.

I don't have the club CD i should have a bit on file ,i used your software a bit for the nbtv crt monitor ...what would we do with out your work we would be no where !

I have to hit the sack now as I have an early start in the morning but I will check in to see if you have any more information. Cheers.

[/quote]

Thanks for checking that late post ...i will look into this more tonight

[Harry Dalek]

Harry, what you describe sounds to me as parasitic oscillation.

I will see as Gary suggested with some more videos and see ..This is new to me never heard of it

- Take some metal object, e.g. a small fully metal screw driver, or a piece of bare copper wire
- and touch the input pins of the LM311 with it.
- Yes, you have the screw driver in your hand, so it is also connected to you.
- Look what happens with the rolling.
- If it stops if you touch a certain point, one of the inputs of the LM311,
- then solder a small capacitor, e.g. 220 pF, to that point,
- the other wire to ground.

Well i will sure try it out Klass ...i will hook it up tonight and see what happens when i follow your procedure ..Wow this is some interesting effect if it works .

Yes indeed, this looks as magic, some people do this with a wetted finger in stead of the screwdriver and this also known as "the wet finger method".

The capacity of the oscilloscope probe does the same as the capacity of your body or the 220 pF.

I sort hope it does work as i want to see the effect ...i will hook it the power to every thing and give it a go ...

[Harry Dalek]

I think Klaas the touching the lm311 input pins with a screwdriver seems to change the speed ,didn't stop the roll but i suppose depends on motor speed adjustment .

All the other videos i have tried today theres a roll ..just seems to work on that one i mentioned .

Oh well may as well get back to the camera ..i know now the disk needs improving but is not the cause of the wriggly video .

[grahamhunt]

Gary mentioned in an earlier post about thin needles whilst checking the needle sizing for a 0.5 needle i came across a size 16 needle at 0.2 mm and a size 15 at 0.24 mm both sold as beading needles hope this my be of use
Graham Hunt

[Harry Dalek]

Gary mentioned in an earlier post about thin needles whilst checking the needle sizing for a 0.5 needle i came across a size 16 needle at 0.2 mm and a size 15 at 0.24 mm both sold as beading needles hope this my be of use
Graham Hunt

Hi Graham
I will look into that funny enough my mind was on this this morning .

With the needle i don't really use the size of the needle but the tapered to a point part .

Albert has a good procedure doing this and keeping same size hole.
viewtopic.php?f=1&t=1523&hilit=question&start=30

Really with this disk from 2012 i didn't really know what i was doing apart from i was trying to make it small and only by eye and see what different size aperture holes i could use on the flying spot scanner ...the hole size here was half a mm small but not small enough for this ...ok but i think i can improve .

From testing on aluminum foil i can see i can do a lot better ......and with the use of my usb microscope i can at least see the size and try and measure it .

Looking into that side of it i can take a picture of the aperture hole with a ruler on 1mm i will try and get this as large as i can as a picture ...i have a picture of a micrometer ruler 100 spacings per mm i will resize this over the photo lined up across the mm spacing that will show at least to this scale what i can do .

[Harry Dalek]

Here are a few quick tests seeing what small holes i can make ...
The Nipkow i am using against foil and thick light proof black paper i have used in the past on the 2 drum monitors .
I was thinking the foil would be easier but the paper is .
Needle was just what i had handy for testing .

[gary]

Harry for some reason, maybe it's lack of scale in the pictures, but that needle looks huge AND blunt!