Arduino Nano PI Main Discussion

[Qiaozhi]

Tried a 1k resistor at R1 and no change I'm afraid. Probably best to source some different manufacturers 7660's, do you think?

That would be my next step.
In the meantime you could continue building the rest of the detector with the 7660 in free-running mode.

[Carl-NC]

Sounds like a loading problem. Wrong cap values?

[MATT]

That would be my next step.
In the meantime you could continue building the rest of the detector with the 7660 in free-running mode.

Ok thanks for your help so far, I'll report back findings.

[MATT]

Sounds like a loading problem. Wrong cap values?

Thanks, I have double-checked all my caps but I will go through them again, I am a novice at this so your help is appreciated.

[Carl-NC]

You say it looks good until you plug in the '5534. Have you tried a different opamp?

[Qiaozhi]

You say it looks good until you plug in the '5534. Have you tried a different opamp?

I thought Matt had already tried a different NE5534, but now when I look back over the thread I can see that may not be the case.
However, the -5V supply doesn't drop when the 7660 is free-running.
It would definitely be worth trying a different opamp though.

[MATT]

You say it looks good until you plug in the '5534. Have you tried a different opamp?

Thanks, yes that was one of the first things I tried before my original post.

[MATT]

It's must be a problem with the 7660 because your scope image (with R1 in-circuit) is the same as I see here.
Referring to the datasheet for the 7660, on page 8 it shows a series resistor of 1k, but I've never had a problem using 10K. It might be worth a try to reduce the value of R1 and see what happens.
Certainly no-one else has ever reported seeing this problem.

I received some different 7660's today and now getting -4.76V at TP3 . So thanks again for your help diagnosing this issue.

For reference this is the one that works https://www.bitsbox.co.uk/data/sfic/ICL7660S.pdf

Avoid this one:
https://docs.rs-online.com/8c75/0900766b814f3c41.pdf

[Qiaozhi]

I received some different 7660's today and now getting -4.76V at TP3 . So thanks again for your help diagnosing this issue.

For reference this is the one that works https://www.bitsbox.co.uk/data/sfic/ICL7660S.pdf

Avoid this one:
https://docs.rs-online.com/8c75/0900766b814f3c41.pdf

[Qiaozhi]

Alfonso (ahermida) has noticed that the EFE sample delay changes when the Delay pot is adjusted.

Although the EFE delay setting is not that critical, it is not supposed to change when you adjust the delay.
It's an easy fix though. Simply remove the following line from the calcTimerValues() routine:
temp4 -= temp3 + temp2;

I've added a second item to the errata list here -> Arduino Nano Pulse Induction Metal Detector Project - Published March 2021

[Jeg]

Hi Qiaozhi
Thanks a lot for releasing this great project.

Why do you think that EFE pulse shouldn't move when we adjust the main sample delay pot? We have to introduce the EFE pulse at a moment in which we are sure it is far from the main sample pulse. So my guess is that it has to move so to keep the time difference between main sample and EFE steady as we adjust the delay pot.

Excellent job, thank you guys, and thank you George Overton for opening this project.

[Qiaozhi]

Hi Qiaozhi
Thanks a lot for releasing this great project.

Why do you think that EFE pulse shouldn't move when we adjust the main sample delay pot? We have to introduce the EFE pulse at a moment in which we are sure it is far from the main sample pulse. So my guess is that it has to move so to keep the time difference between main sample and EFE steady as we adjust the delay pot.

Excellent job, thank you guys, and thank you George Overton for opening this project.

The important thing is that the sample pulse and the EFE pulse should be the same width, so the detector will still work ok even without the code change. With the current sketch, the EFE delay is being increased as the sample delay increases, whereas it is normal to keep the delay at a fixed position, and only adjust the sample widths.

By the way, Qiaozhi is a transliteration of George in Mandarin.

[Jeg]

wow Qiaozhi you are the writer of this book?! That is a great surprise! You have made a great work here, as in many projects over those years! No words for expressing my gratitude. I hope i can trace the book with the pcb boards by living here in Greece. Can't wait to mess with it

[Qiaozhi]

wow Qiaozhi you are the writer of this book?!

Correct.

I hope i can trace the book with the pcb boards by living here in Greece. Can't wait to mess with it

I wish you success with the project.

[Jeg]

ethernet cat7

Hi all
I would like to constract a frame coil of 1,20m X 1,20m, for my ANPI. Do you think that an ethernet cable CAT7 would do the job? Any other sugested type of cable for this job?