Who has used the 4046 to synchronize their nipkow wheels?

[Viewmaster]

To try and understand a little more on the 4046 I wired one with NBTV sync pulse input as normal.
Instead of the opto fork input I injected a variable freq sq wave from my scope and I'm now watching the many variable wave patterns from the output, pin 13.
The 4046 is quite an interesting little devil isn't it?
Albert.

[Panrock]

As previously mentioned, I'm using the standard circuit and it gets me both line and frame sync. To do this I removed a block of four pulses in the place found to give the correct frame phase. To do this, I simply added bits of black insulating tape over the sync holes until I got the best result.

Having said that, the frame sync action is weaker than the line. However it does work - don't really know why - and that's good enough for me.

Steve O

[Viewmaster]

The old 4046 sync chestnut seems to be older than we thought.
3 years ago this forum struggled with the 4046 and its motor control circuits.....

http://www.audiokarma.org/forums/showthread.php?t=45863

Maybe some of those guys are now on this forum?...... Mbates, Old tv nut, Yagosaga, bele2009. Any takers?
Albert.

[Viewmaster]

Interestingly, if you do a search for '4046' on this forum you will find many references to problems with sync using this pll. ...Certainly, the 4046 seems to cause more headaches for NBTV builders than most other items in the build. Albert.

The problems that I see NBTVers have breaks down into two areas. Firstly as Pete mentioned previously, the missing pulse causes some headaches, secondly the mechanical time-constants which vary from one build to another.

Going back to this thread...
Some discs are very light and have little inertia (darvic for example).
Others are heavy (ali or steel) and have a great deal of inertia.
As Steve mentioned the mech time- constant varies wildly from one NBTV to another.

In my recent ongoing experience with my Edikow I am fast coming to the conclusion that sync problems are caused by the incorrect mechanical inertia of the disc in relationship to the component values in the 4046 damping/feedback circuit.
It would be interesting to see how circuit component value varaitions and disc inertia varied amongth those NBTVs with and without sync problems.

Maybe we could eventially weigh our discs and so determine the best component values to use in the 4046 circuit.
Albert.