alternative synchronization

[bigscreen]

Realy great work and the results are very nice pictures with clear viewable
dancer.
I realy impressed from the steady picture with this circuit to become sync.
I would like to know if there is some more explenation about the working of it, I mean what makes it tricky to catch the sync ?
I never have seen such way of syncronisation before, who did invent this
anyway, it sounds very intresting to know something more of it if possible
ofcourse.
Congratulations with the results dear Holtzman !

[Marcus]

That is a great result, do you have to get it in sync and then push the key down to lock it in?
This a great simple sync system, thanks for the schematics too.

[Mike Willis]

Thanks for the diagrams Holtzman...it makes it a lot clearer. It looks like I may have everything I need already, so I'll try and breadboard it together. I may try a disk that has the sync holes an inch or two inside the viewing holes...do you think this will work?

Cheers,
Mike

[bigscreen]

Dear Holtzman,


Are the LDR and the led placed in a darkened box (schielded from extern light) ?
And what kind of Transistor did you use in the motordrive circuit please ?
I just guess this is the way you get it work, right ?

I would like to have it a try to, I just need to know this lil information first
to make the right desission.
Thank you and best greetings from Belgium.

[holtzman]

Hello dear friends,
that's how it works:
The motor is powered intermittently via LDR driver which provides pulses according to hole pattern passing LDR/LED assembly. The main speed regulator pot is not in the motor driver, but in the sync amplifier. The brighter is the LED, the quicker it runs. But the LED light is pulsing, too. Once the disc reaches speed just below sync speed, the key should be pressed a few times shortly. This "kicks" the disc speed, and timing of the sync pulse flashes coinsides timing of the holes. The speed locks. You can then press the key some more times, in order to get the right frame sync.
The advantage of this system is its simplicity. There are disadvantages, too:
1. It is not fully automatic
2. The motor gets hot because it runs on higher current intermittently
3. It depends on the input signal levels and needs to be readjusted for different signals.
Exact type of transistor used in motor drive is not so important, I guess. I used some hudge one from VCR power cirquit, it worked well also in the Klaas LEd driver and is very similar to BUZ11. The LDR is about 5 mm diameter, it sits in a tube of dark isolation tape. The sync holes are 4 mm. The opto-fork needs some hood for darkness, though I just dim the light and it works. Last but not least: the power supply should be stabilized, no fluctuations or 100Hz noise can be pesent.

[holtzman]

This is my opto-fork sync sensor. LDR which resistance varies from 1500K in darkness to 0.5K in full light.

[bigscreen]

Dear Holtzman,

I m started with drawing a picture from how I would place all the components on one single board, but I m not sure how you did connected the two transformators with the circuits.
Could you please let me know where the leads are going from the first
transformator, and from the second one. Just to be sure not to make any
misstake with the leads.You can open the drawing in paintbrusch.
Thank you for this effort.

Best greetings, Patje.

[holtzman]

Dear Patje,

I think you got it right but not sure for 100% your schematics is error-free.
Since I am NOT proffessional in electronics, I made some confusing change which is against the rules maybe but does work.
In particular, in the cirquit driving one sync LED, the connection to the signal source is INVERTED. In other words, 0v is not connected to the ground of the signal cable, it's connected to the cable core. So don't be confused that the ground is not connected to the 0V as it is in the video driver.

For this reason, I use 2 transformators: one feeding the video cirquit, another feeding the "inverted" sync cirquit plus the motor cirquit. So far the motor does not consume too much energy these 2 parts are quite happy to share 1 transformator.
Best luck, I'll post some image later!

[bigscreen]

I understand dear Holtzman, I dont know if this small circuit could make
things work this way, I guess it must be possible and it use only a few
small components....

[Steve Anderson]

Patrick, I'm afraid that that circuit won't work, it's not biased correctly, here's my version, it and a few others are within the thread 'Simple Display Driver'.

Steve A.

[bigscreen]

Thanks Steve !

I guess there has now to changed even something on the entrance from Holtzman's modified syncroniser before to connect your circuit , right ?

I got his circuit here Steve...

[holtzman]

Thank you Steve for the inverter cirquit!
Excuse my "narrow bandwidth" understanding, but I still can't figure out why it's so important to add it instead of just swapping the input leads? The main reason seems to be the same power supply, are there other concerns?

Patje, I post here the connected cirquits as I would connect them and the general layout as it is up to day, without inverter. Right now I have all the electronics apart from the monitor, it is being transferred to a new 60 lines machine which I have built 80% but have no time to finish I remember that there was much trouble with the separation, those diode and resistor you signed by the ellipse. Only after adding the 10K resistor the diode began to work.

[bigscreen]

Great job Holtzman, I thank you very much for this effort, I hope to see
your results with the 60 lines soon or later when you got the time for this challenge.
I started today with building a simple mirror drum projector/monitor
the way that David Gentle has described into the newsletter Vol 34 N°3
page 5 and 6.
I hope to got some pictures soon from the progress with the drum.
Plenty of work when you know that there are 64 brackets, each one need to be handled severall times, cut, drilled etc...
This instead of starting with a 60 lines monitor, becouse I dont know sure if it is possible to get 60 lines composed videosignals on a CD, and to play back with the CD player, they are not high enough in Frequency I tought
to record the signal... Only a convertor could be used for this, to convert the 625 lines into 60 lines, but this convertor is a lil bit expensive for some
like me....
But I got goal to create a bigger picture with this projector/monitor system
and it is realistic becouse the new Luxeon leds from 3 watt.
So, there I go again !

[gary]

Patrick, you are so prolific with your NBTV projects I wonder where you keep your old projects - you must have a warehouse full of them by now!

I am not sure this will help but please be aware that Video2NBTV can create 60 line landscape NBTV (if you needed portrait this could be arranged) - you need a PC and a soundcard capable of 96kHz output however if you want to play it out (a CD player is restricted to 44.1kHz, however some DVD players *may* play 96kHz wave files).

Certainly for your development phase this would be a cheap and easy approach if you have a PC available.

Good luck!

[Steve Anderson]

Thank you Steve for the inverter cirquit!
Excuse my "narrow bandwidth" understanding, but I still can't figure out why it's so important to add it instead of just swapping the input leads? The main reason seems to be the same power supply, are there other concerns?

Well, it's 'OK' (sort of) with a battery powered CD player but it can introduce noise in certain circumstances, it's just not good practice to 'cross grounds', it also precludes the use of a mains powered player which could be grounded (or at least should be, although many are not).

I don't understand the function of the diode, perhaps you could explain, I can't see its function.

Steve A.