alternative synchronization

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thanks

Postby sharafi123 » Wed Aug 19, 2009 5:27 pm

Hi holtzman
thanks for evry thing. what about sync circuit?
best regard
mohammad
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Postby bigscreen » Fri Aug 28, 2009 9:48 am

I did some more test and made a small modification in the circuit to get it work, and it is working now, there is a syncrone speed, but....when the
tracs changed, there is loss of syncronisation and there is the need to set it properly again.
I did connect a second LDR in the circuit and placed this second one near the luxeon light, (close as possible) to get the flikkering lightpulses on its
surface. Afther setting the speed correction it go's into sync, but it takes some seconds to got it bouncing free. Till the next track and there you go again..... :shock:
I will do some more experiments with it, till I know enough about it and future will show me if it is realy a usable circuit for that small monitor.

Still working on it.......
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Postby holtzman » Fri Aug 28, 2009 6:15 pm

Great news bigscreen :)
I don't understand where the second LDR is located. From the other side of the LED? Does the light pass through the sync holes or it shines directly on the LDR? I am very curious :shock:
Meanwhile, after some try-n-error sessions, I made some progress and I think I have a solution for the "hunting" problem. It never worked for me untill I put a direct drive motor, without belt&pulley. Now there are 2 independant motors: one with pulley with no speed control, another direct drive connected to the cirquit. I still had no time for testing it but the results will come soon 8)
Thanks a lot for now!
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Postby bigscreen » Fri Aug 28, 2009 8:59 pm

Hi, Holtzman,

I did place the second LDR above the Luxeon where I got a hole in the
lighthouse to pick up much as possible the flikkering light, and the first LDR just like your circuit begind the disk but....
I m thinking that the most biggest problem is, the flikkering led begind the disc. This led needs to show a very strong 400 Hz. signal to got a good respons with the stroboscopic wandering hole and this may needed to been worked out with another way of sync-separation, amplification and led driver for this.
I got this to try out ofcourse to know..... :wink:
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Postby Roland » Thu Dec 01, 2011 10:52 am

Really like the idea of this LDR based synchronisation.

I've now got my LED array working well enough (but there is always the temptation to fiddle with it a bit more!) and the LM317 is wired up for motor control. I really could do with some sync but I don't think the 4046 circuit is for me.

Anyway just ordered some LDRs on ebay - though I have one I bought back in the 1980s which may work well enough for a bit of testing.

:)

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Postby holtzman » Fri Dec 02, 2011 12:37 am

In my drum monitor i used modified circuit, which is better than original one posted here. The change is that it uses sync pulses from the NBTV signal to INTERRUPT power for the motor, instead of supply power to it. Since pulses are short, too much power was not in use with the old version, and I used it with 2 motor csheme which was cumbersome.
The new circuit is closed inside the monitor and unfortunately I did not make any diagramm - nobody seemed to be interested in this kind of sync then. If you want to try it, eventually I'll open my monitor and make a diagram of it. It consists of 3 parts: blinking LED driver, motor driver, and damper. And you'll probably need an inverter unless you use different power supplies for video and sync.
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Postby Roland » Fri Dec 02, 2011 9:41 am

Hi Holtzman - thanks for the update. Your new improved circuit sounds very interesting - but don't worry to much about posting it now. I'll try to build your original circuit as described here.

I was planning on using an inverter so I can share the PSU. I'm using a 20v laptop PSU.

One question - I know very little about synchronisation - but I understand that 'club' standard video has a missing pulse to help with frame synchronisation. I can live without frame synchronisation - but do you now if your circuit is able to sync with video containing this missing pulse?

Thanks

:)

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Postby holtzman » Sat Dec 03, 2011 7:35 am

Oh yes, my circuits do work on signal with missing pulse - they don't feel it. The adjustment of frame is manual, like it was with a phonic wheel.

If you want to try my old scheme, consider a two-motor drive, with a sync motor direct driving the disc and a main motor connected by pulley.
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Postby Roland » Sun Dec 04, 2011 11:32 am

Thanks.

As for motors I'm only using one which directly drives the disk. Presumably with 2 motors - the majority of the driving effort is by the belt connected motor - and the sync motor just boosts the speed as required?

If this is the case then maybe I can keep the LM317 voltage controller to drive the disk at just under the correct speed and use the sync circuit to boost the voltage to the same motor.

Prior to really thinking about sync - I had thought to use the LM317 to bring the disk up to speed anyway and then just switch over to the sync circuit.

I'll experiment and see what I can make work :) The LDRs arrived today and I just need to clear my work area and give it a go.

:)

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updated circuits

Postby holtzman » Sun Dec 18, 2011 7:18 am

Finally I managed to make a diagram of my latest sync circuit. For those who may be interested, I post it here. It works well with one motor.
Roland, I found out that the led driver circuit is not up to date in this thread, too. So I post the updated single led circuit as well.
In motor driver, C1 and R6-R7 act as a damper. The damper is needed to prevent "hunting". R5 helps to fine-tune the LDR sensivity, which also prevents hunting. R2 is the speed control.
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Re: updated circuits

Postby Harry Dalek » Sun Dec 18, 2011 11:21 am

holtzman wrote:Finally I managed to make a diagram of my latest sync circuit. For those who may be interested, I post it here. It works well with one motor.
Roland, I found out that the led driver circuit is not up to date in this thread, too. So I post the updated single led circuit as well.
In motor driver, C1 and R6-R7 act as a damper. The damper is needed to prevent "hunting". R5 helps to fine-tune the LDR sensivity, which also prevents hunting. R2 is the speed control.


Hi i am always interested but trying lots of different things is my trouble.

Can i ask do you not use the sync pulse at all in the circuit ? i see your using feed back from the opto fork to control the motor.

Its a very nice little circuit to do the job i will try it in time it looks like a nice in between manual and full automatic ...i do take notice of the videos and your circuits so its well worth posting for me anyway ..

I was looking at your first televisor the other day on the forum you have come a long way from that one is it still around btw ..
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Re: updated circuits

Postby Roland » Wed Dec 21, 2011 11:29 am

Thanks - very interesting.

I've got as far as simulating the original LED driver circuit in LTSpice and building (but not yet testing) the signal inverter.

I notice you have some quite heavy duty power resistors there! I'll have to get hold of some.

I have a few other challenges around my disk as it is slightly warped - though runs fine at speed. I think this will limit how close I can get the LED to the LDR - but I'm going to give it a go before trying any drastic measures to flatten the disk.

Thanks again,

:-)

Roland.

holtzman wrote:Finally I managed to make a diagram of my latest sync circuit. For those who may be interested, I post it here. It works well with one motor.
Roland, I found out that the led driver circuit is not up to date in this thread, too. So I post the updated single led circuit as well.
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Postby Roland » Thu Dec 22, 2011 12:03 pm

Hi again,

Just looking at your new motor driver circuit. Can I just check - are R6 and R7 both 33ohm - or is that the combined/effective value of the 2 resistors in parallel?

Also whats the rated voltage of your motor? I guess you have this circuit on a different power supply as its moved up to 24v.

I think my motor is rated at 12v and I get 750rpm at about 9v.

Thanks

:-)

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Postby holtzman » Fri Dec 23, 2011 3:30 am

Hi Roland,
R6 and R7 are 33 Ohm each in my circuit, making about 17 Ohm in parallel. BUT: these resistors plus the caps in parallel with them are optional. They form a damper which fights hunting while using BELT drive. If your drive is direct, chanses are you won't need damping at all. If you use 750 rpm the power is lower and maybe even less wattage resistor of 17 Ohm will stay cool.
My motor is from inkjet, the one moving the heads. It gets about 15V and stays warm. Probably, your motor won't last long because direct drive needs lots of torque. I have burnt one motor this way in my first tv - its brushes were gone. But there was my first driver in use - the second is much more effective thus less current will be needed.
Good luck :)
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Postby Metallica Man X » Fri Dec 23, 2011 7:24 am

I'm digging the simplicity of your design...I may have to borrow the concept for my own creation ;)
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