NBTV Camera Question

[gary]

...cutting the center out a bit larger will make it moving about easy .

Well I don't want to second guess you because I don't know what tools you have at hand or what your skill level is but from my experience increasing an existing hole's diameter and/or making it a "loose fit" would, for me anyway, guarantee non-concentricity (and hence "wobble"). Good luck!

[Harry Dalek]

...cutting the center out a bit larger will make it moving about easy .

Well I don't want to second guess you because I don't know what tools you have at hand or what your skill level is but from my experience increasing an existing hole's diameter and/or making it a "loose fit" would, for me anyway, guarantee non-concentricity (and hence "wobble"). Good luck!

I have made the clear plastic encoder ,it doesn't have to be really there for good i really just want to see if the cause was the the cut out slots and being off center which is pretty much what we think ..

I can make a nipkow with the paper encoder again ..just see how it gos ,the main problem now is it will not work until i wack a pot on that photo trany .

Yes i see your point this is not my first choice but i am interested to see what that sync bar looks like minus my last encoder adjustments .. less wobble to the bar we can say its really down to centering the encoder

[gary]

the main problem now is it will not work until i wack a pot on that photo trany .

what will the pot do harry?

[Harry Dalek]

the main problem now is it will not work until i wack a pot on that photo trany .

what will the pot do harry?

Reduce the sensitivity of the photo transistor remember i was having trouble at the start it was still reflecting to much off the black ...its not my idea i notice a few people who have made this circuit have that on the emitter which i think they worked out the problem before me.

[gary]

Oh I see, fair enough, I thought the original problem was just that your print out wasn't dark enough or you were using glossy paper or something. Oh I remember now, I remember expressing some doubt about the need to add an adjustment because unless both white and black were clipping (i.e. the signal is being driven to the rails) then the differential between black and white would be the same - and it is just the differential we are after.

None-the-less if it works it works.

PS: I think the use of a trimmer or pot in some circuits has more to do with preventing over driving the next stage and obviously you aren't doing that.

[Harry Dalek]

Oh I see, fair enough, I thought the original problem was just that your print out wasn't dark enough or you were using glossy paper or something. Oh I remember now, I remember expressing some doubt about the need to add an adjustment because unless both white and black were clipping (i.e. the signal is being driven to the rails) then the differential between black and white would be the same - and it is just the differential we are after.

None-the-less if it works it works.

PS: I think the use of a trimmer or pot in some circuits has more to do with preventing over driving the next stage and obviously you aren't doing that.

Hi Gary
As i was thinking the encoder disk as is is not giving a pulse yet...But i forgot i did make another encoder on a past nipkow before so i just gave it a run ..its centered better and perhaps i have cut the slots out better it does have the missing pulse still...
its saying on my scope 387 hz not moving at all. the sync bar is better than the last disk not 100% but proves it can be better and wobble is a factor.

I should have said i hope it works on the non cut encoder but yes lets hope it works ..pain when things don't !

[gary]

Indeed, that is much better Harry, in fact that's good enough to play on TBP straight off, so it is up to you as to whether you want to improve on it.

I have to say though I simply cannot understand why you are having problems reading the encoder unmodified - I have used this arrangement dozens of times without having to have tweak anything - it is so straight forward as to be almost totally fool proof. The only thing I have ever had to do is adjust the distance the sensor is from the encoder. It's totally beyond me.

[Harry Dalek]

Indeed, that is much better Harry, in fact that's good enough to play on TBP straight off, so it is up to you as to whether you want to improve on it.

I have to say though I simply cannot understand why you are having problems reading the encoder unmodified - I have used this arrangement dozens of times without having to have tweak anything - it is so straight forward as to be almost totally fool proof. The only thing I have ever had to do is adjust the distance the sensor is from the encoder. It's totally beyond me.

Hi Gary

Yes i was happy when i found this other Nipkow more so that i did a better job encoder wise ,have to see what this Nipkows like now i have always used the other one.


The black part of the encoder i am sure is at least 80% black that should be enough for it to work all i again can think of is the photo transistor is just to sensitive ...when i moved this new one between the white black i can just see a slight bump on the scope perhaps a line thickness dreadful really ...
The back of the cd one the cut out gives a good pulse difference to the white i think more so because its shiny black so the white could very well be black as well and it might still work ? i will have to do an experiment on this side .

[Harry Dalek]

Heres a video wav file of me waving my encoder nipkow disk infront of the camera ...theres a bit of noise again i think its the computer but its a lot clearer now .

Once i get rid of this noise problem i will play around with the light sensor feed back control ...i am happy with this nipkow

[gary]

all i again can think of is the photo transistor is just to sensitive

But you are using the same sensor as I do aren't you? and paper is paper, ink is ink - what on earth could be different?

Sorry about obsessing but silly things like this annoy me and I like to determine what the actual cause is even when there is an easy work around.

I still suspect the reflectivity of the paper itself - most sheets of paper have a gloss side and a matte side - could this be the case in your set up?

One other thing to try is to de-focus the sensor a little by moving it back from 5mm - but you may have tried that?

Edit:

I suppose you may also be allowing more current to flow through the transistor by using different a resistor value, so a pot or a higher resistor value may work.

I am not sure that you posted the encoder sensor circuit did you?

[gary]

Heres a video wav file of me waving my encoder nipkow disk infront of the camera

Yes quite recognisable.

Your speed is not quite as good as in previous attempts varying from 393 Hz to 417 Hz, with an average frequency of 406 Hz

I notice quite a lot of electrical noise on this example too, but mainly where you are changing scenes.

None-the-less it plays quite well on TBP.

[Harry Dalek]

But you are using the same sensor as I do aren't you? and paper is paper, ink is ink - what on earth could be different?

Yes i have no idea gary 330 ohm on the ir led and 22k on the emitter of the photo trany ..must be a reason more than likely a silly one i have missed ...

Have to point out last night all i did was replace the that encoder i didn't play with the light reflective sensor distance or any thing ..i would like to work it out as its easier for me to have a print out with out cutting slots out and it would work better as well.

Sorry about obsessing but silly things like this annoy me and I like to determine what the actual cause is even when there is an easy work around.

mmmm yes don't worry i don't like this problem as well has to be a reason... all i can think of doing is using a black texta on one or a bit of paper and seeing if its enough to trigger the bugger between the white and black .

I still suspect the reflectivity of the paper itself - most sheets of paper have a gloss side and a matte side - could this be the case in your set up?..

I am pretty sure the papers matte both sides gary but i will double check that ...i know it really likes a gloss so type of paper could be the case as in my set up with cutting out the slots the paper white is matte and the cd is gloss black .

One other thing to try is to de-focus the sensor a little by moving it back from 5mm - but you may have tried that?

I will try but did not real adjustments for that encoder yet ...i will alo see if we have other types of paper for printing ..wonder if photo paper would be any good ...is yours just matte paper Gary ?

Edit:

I suppose you may also be allowing more current to flow through the transistor by using different a resistor value, so a pot or a higher resistor value may work.

Its some thing to try it would be any easy fix if it works ..i'm getting the soldering iron out today fix a 2 grounding problems so i will wack a trimmer pot .

I am not sure that you posted the encoder sensor circuit did you?[/quote]

Its in the PLL motor control circuit few post ago is it the same as yours ?

[gary]

That seems OK Harry, I use a 10k but at 6V so about par.

I just use standard photo-copier paper (reflex or equivalent).

What kind of printer are you using? Are you printing full quality (i.e. not draft).

Edit: also is there a part number on that sensor (in case I have sent you a different type).


I attach a video of my arrangement - do you see anything different? - how do the encoder segments compare to yours?

[Harry Dalek]

That seems OK Harry, I use a 10k but at 6V so about par.

Ok that sounds good then its not that .

I just use standard photo-copier paper (reflex or equivalent).

Yes that sounds what my wife uses thats the same .

What kind of printer are you using? Are you printing full quality (i.e. not draft).

A Hp ink jet type ...mmm the full quality well i think we might have something here ! i am not sure its full as i recall it did print to fast to be on full quality...mmmm perhaps its this .

Edit: also is there a part number on that sensor (in case I have sent you a different type).

I will look and get back to you on this might be on the under side i can't see.


I attach a video of my arrangement - do you see anything different? - how do the encoder segments compare to yours?

Just downloading now gary i will view .

Sorry for the delay i have been doing some soldering...panel mounted the PLL led and more interesting put in a 2 way switch to switch between the crystal oscillator and encoders 555 monostable to see if what we were talking about a while back works mixing the crystal oscillator in the video mixer once the motors up to pll speed ..should be synced so have a cleaner video sync but might still need another monostable perhaps to adjust the width looks bit wide ,well find out soon .

[Harry Dalek]

Looking at the Video Gary there are differences .

Your reflective sensor is horizontal to the horizontal slot .

Mine is horizontal but my slot would be sort of angled vertical.

Yours is close looks at 5mm mines more looking more like 20mm but using it as is thats what worked .

The reflective sensor you sent has this written on it HOA1405-2 8839 Mexeco