Mpp beach rev-e step 3 problem

[Hrthomas]

Hi
I have a problem at step 3 on rev-e build.
"You can also see that the TX oscillator is synchronized to U9 (LT1054 voltage converter) by
monitoring TP2 with an oscilloscope (channel 1), and U9 pin2 (channel 2)"
See photo, TP2 is yellow, pin2 U9 is pink..

[Qiaozhi]

Hi
I have a problem at step 3 on rev-e build.
"You can also see that the TX oscillator is synchronized to U9 (LT1054 voltage converter) by
monitoring TP2 with an oscilloscope (channel 1), and U9 pin2 (channel 2)"
See photo, TP2 is yellow, pin2 U9 is pink..[ATTACH]45646[/ATTACH]

The internal oscillator of the LT1054 runs at a nominal frequency of 25kHz, so you will need to change the timebase on your scope to zoom in and see the synchronization.

[Hrthomas]

Hi, is this correct?

[Qiaozhi]

Hi, is this correct?[ATTACH]45650[/ATTACH]

Yes, that's correct. As it says in the Build Document:
Since the TX oscillator pulse rate is considerably lower than the LT1054’s internal oscillator, it is not possible to synchronize the diode pump from this external signal. In this circuit the TX oscilator causes the diode pump’s internal oscillator to pause momentarily, and then restarts it so that both oscillators are in sync.

[Hrthomas]

Ok, thanks then i will move on to next step

[surfdetector]

Yes, that's correct. As it says in the Build Document:
Since the TX oscillator pulse rate is considerably lower than the LT1054?s internal oscillator, it is not possible to synchronize the diode pump from this external signal. In this circuit the TX oscilator causes the diode pump?s internal oscillator to pause momentarily, and then restarts it so that both oscillators are in sync.

Hi,

I have just reached step 3 and I note that my image varies somewhat from the one that Hrthomas posted above and I would like to check prior to moving on. Thanks.

[surfdetector]

MPP Beach Rev E Step#3

Hi,

I have just reached step 3 and I note that my image varies somewhat from the one that Hrthomas posted above and I would like to check prior to moving on. Thanks.
[ATTACH]49714[/ATTACH]

So as stated in my previous post I am on Step #3 of the MPP Beach Rev E and to quote from the build document..... You can also see that the TX oscillator is synchronized to U9 (LT1054 voltage converter) bymonitoring TP2 with an oscilloscope (channel 1), and U9 pin2 (channel 2).

I have checked this many times and it appears that the waves forms only synchronize very rarely. I managed to get a picture before the wave form changed back to non-synch. Hopefully someone will be able to add some knowledgeable illumination on this for me and what might be the cause. I appreciate the help. Thanks.

[Polymer]

Hi surfdetector,

I am replying here instead of PM. If I recall correctly, it is a "quasi synchronisation".
I was asking similar questions hopefully not driving Qiaozhi nuts in the process.
Can't find those posts ... dang.

Important is this part during the sampling phase. Check it later if you like. It works. Don't worry about it and continue building.

[surfdetector]

Hi surfdetector,

I am replying here instead of PM. If I recall correctly, it is a "quasi synchronisation".
I was asking similar questions hopefully not driving Qiaozhi nuts in the process.
Can't find those posts ... dang.

Important is this part during the sampling phase. Check it later if you like. It works. Don't worry about it and continue building.

Hi Polymer,

Thanks for the advise. I have done a short video of the issue which you can view through the YouTube link. The issue I find is repeatable each time after powering down and turning back on again. You can see the synchronization begin to drop out at around the 40 second mark.

https://youtu.be/3YXwde_W-RY

[Qiaozhi]

Hi Polymer,

Thanks for the advise. I have done a short video of the issue which you can view through the YouTube link. The issue I find is repeatable each time after powering down and turning back on again. You can see the synchronization begin to drop out at around the 40 second mark.

https://youtu.be/3YXwde_W-RY

Since neither the TX oscillator nor the LT1054's internal oscillator are crystal controlled, they are subject to temperature drift. However, as you can see from the video, the two remain "more or less" locked together, and the LT1054's oscillator is not free-running. You are (of course) free to experiment and find a better solution. Unlike the ICL7660A, the LT1054 is capable of operating with a much lower sync frequency, so you might be able to operate it directly from the TX oscillator. Personally, I haven't tried that. In fact, the original Minipulse design used a discrete voltage converter that was free-running, so the current implementation is a big improvement.

[surfdetector]

Thank you for for taking the time to review my question. I am very much a neophyte but am learning .
Cheers

[PITER]

now home time I have taken pcb minipulse, mounting I was wrong connecting volatage to reverse, lt1054 does not work, can I replace it with 7660s ?? just to keep going

[Qiaozhi]

now home time I have taken pcb minipulse, mounting I was wrong connecting volatage to reverse, lt1054 does not work, can I replace it with 7660s ?? just to keep going

You can, but remember that the 7660S (and 7660A) have an absolute voltage rating of 13V. Ideally you should not go above 12V.