alternative synchronization

[bigscreen]

Hello Gary,
When I started with NBTV, I didkeep my first monitor and camera for a couple of years and later I did used the elactrical parts and some other
pieces to rebuild other monitors, or Camera's.
Some day I had 6 devices into my house, but mostly I did dismantle them
to keep my budget in the green zone.
Some are given away as a gift and one Camera/monitor is still in a school
in Brussels.
Today I have still 3 devices, one drum-monitor, one nipkowdisk monitor and one camera/monitor from severall years ago build into a metal photoslides-box constructed as a kind of "Mecano".
All my contructions are publisched in the Newsletters of NBTV and mostly with some pictures from the devices.
New ones will be there soon !....

[holtzman]

Thanks Steve!
The diode acts as separator, it cuts away the video signal leaving the sync pulse.

[Klaas Robers]

I also think that the red diode (in the diagram) isn't needed. Just replace it by a piece of wire. The video is more or less removed by the non lineairity of the FET. In fact you are using the gamma correction upside down and that stretches the now positive going sync pulses considerably and compresses the remains of the video signal. And more: most of the video part is pushed below the threshold of the FET.

[bigscreen]

Okay, i did build the circuits and the inverter from Steve seems to work.
Even the motorcircuit with the LDR seems to works when I tested the LDR directly with a lightspot from a separate lightsource, so the TIP 41 is doing the job easely.
But when trying to get the whole circuit working, there is going something wrong.
I find out that I got only a signal from 2 Volts entering the Gate from the IRF520 and I think that this is not strong enough to make the fet working.
I replaced this one with a new one, but have connected a resistor from 100r between the Sourse and the -0Volts line.(I m not sure if this is a good idea ?)
Can it work with only 9 or 10 Volts to ?
I only got 13.5Volts with those small transformators, and they are 1.5 Amp.,,,voltagedrop is very high, I loose almost 4.5 Volts......?
And is it normal that I only see this waveform on my scope ? I tought it has to be the same signal like those from the syncseparators with the IC's ?


When I place a variable resistor from 100K between the Drain and the Source, than I can regulate the speed softly, but there is no sync.
Maybe I will have to use more voltage to got the IRF working.

Could it work with a transistor to ?... or do I need to work with this IRF ?
(Just to know)

[Steve Anderson]

Patrick and Holtzman,

I can't get my head around the above circuit, there must me something fundamental I'm missing...like how is the motor controlled? Or perhaps more correctly...I'm surprised that a LDR has a fast enough respose time.

At 40mA the 360/390 Ohm resistor will drop some 15V, the 100 Ohm resistor will lose 4V hence the reason the supply is 20V as shown. Now the LED might be on but I would guess quite dim, simply not bright enough.

If the 100 Ohm resistor wasn't there in the first place remove it. Reduce the 360/390 Ohm resistor to 180 Ohms for your 10V or so supply. Don't forget a white LED drops more volts than the usual red, amber green and even I.R. varieties.

Short out the 20k resistor at the top of the bias chain, again this was designed for 20V, not 10V.

I still don't see how the diode on the input works, if anything it's going to chop off the syncs, or have I misunderstood that too?

...a few suggestions, just wish I could understand how it works...it obviously does!

Steve A.

[bigscreen]

Hi Steve,
Thank you for your help, and indeed, afther that I removed the 20K from the powerline and replaced the resistor from the led with 180r, and got rid with that 100r from the Source, the IRF began to work and the circuit works.
I only need to change the hight from the LDR and Led to be centered with the holes to get a huntless syncronisation.The final results will come later in the avening here.

I hope you understand the drawing and I hope that my explanation is correct....otherwise Landboy could kill me !

But I m almost 100% sure that this is the correct way it has to.



BTW, Steve, how is it in your place there ? Whe see here in the journal heavy storms and rain and a big cycloon (tornado) destroying the country.
Are you living in this area or do whe not to be wurry about it ?

[bigscreen]

But......It seems to easy to work properly !
Afther 2 ouhres trying out and trying out I could not reach any properly syncronisation.
I guess, maybe the syncpulses from the cd are to weak to make the led realy flikkering on 400Hz.
A amplifierestage could fix this, but even than.......
I will see if there is another way to get proper syncpulses and strong enough to make the led flikkering on this signal.
One more try....
There are always still the pcb's from the club ofcourse !

[holtzman]

Hi everybody,
Thanks for your remarks!

Just dropped out of discussion because my second daughter was born
Meanwhile, I had some frustrating failures synchronizing the large 60 line disc and I have to warn you Patrick that my sync is not perfect. It suffers from non-stopping hunting, the speed graph is sawtooth with 1/2 period and I found no solution to damp these fluctuations.
Sorry that no one understand how it works, I am a poor explainer. Sure if you gentlemen do understand, you could help me to sort out that problem Remember it worked pretty good with an LP disc with 32 lines.

It's based on stroboscopic effect. The sync holes and single sync led make additional 1 line "monitor" showing light circles pattern. When the speed is just below sync, this pattern travels clockwise (in case of NBTVA standard). When one of the light circles reaches LDR, it boosts the motor voltage and the speed increases. Only portion of the light circle should remain in front of LDR, in order to provide enough voltage to the motor to run at constant speed. The problem is to prevent self-actuated process of countless cycles of speed jumps up-and-down.

[bigscreen]

Woow, Congratulations Daddy !

I hope nobody is hurt with my changing in names ofcourse, I tought it was Landboy and it has to been Holtzman...

Okay, fine to know that you got even some time to come over and explane us this, even with your newborn doughter.
Please dont feel sorry for that poor explanations, even I do have much problems to understand most electrical situations....hihi...

Anyway, I will try to give it a second change with some tryouts, and even if there is no sync, there are always solutions for that dear Holtzman.

I guess that when I can make the fluctuations stronger into the led with the synctrain, maybe it could work this time, and now I do understand what you mean with that stroboscopic effect and where I have to look at now.
It is still intresting to find out the needed knowleds to make this a usable circuit for more of us, becouse when I see your results in the movie, it realy loks stable and no hunting at all.
I keep in touch with the next results Gentlemen, (I know there are some
looking over my shoulder, waiting for that scream "Eureka !..it works !..."
so I will go on with it for a while....

[sharafi123]

Dear,
waht the number of Transistor that you used for motor drive?
thanks

[sharafi123]

Dear,
Can i use IRF510 for sysnc circuit and video drive?

[holtzman]

Hi Mohammad,

I used BUS11 for all the cirquits, it is basically the same as IRF510. But my sync system is not working properly. If you have a mirror screw, it is even more difficult to make sync because it moves more air and it has less inertia.

[sharafi123]

Hi bigscreen.
Can you put orginal circuit of sync and video amp?
thanks

[sharafi123]

Hi holtzman
Can you give me the orginal circuit of motor sync and video AMP.
If i use 12 volt for them the resistor should be change?
and can i use IRF510 or BUZ11? then IRF510 and BUZ11 are same?

and for invert can i use transistor BC547?
and resistor shuold be change?

best regard
mohammad

[holtzman]

Mohammad,
all the original cirquits are on page 1 of this topic. If you use 12v, there will be not enough amplification. At least 2 power supplies needed, one for image cirquit and another for sync and motor cirquits. Stabilized power supply is needed, it includes voltage regulator.
I think IRF and BUZ 11 are the same in our case. Here is the layout of image cirquit.
I did not try the inverter so can not say what transistor you can use.