Arduino Nano PI Main Discussion

[lc516]

I think the problem is that you're using an ICL7662 instead of an ICL7660.
Although looking at the ICL7662 datasheet, I cannot see anything which explicitly states that it won't run at 1kHz.

Qiaozhi,Thanks for your information.

I used ultimate solustion, I'll open a new PCB make it and add components step by step.


Now,I can get -5v on TP3(ICL7662), I hope that goes well.

[waltr]

I think the problem is that you're using an ICL7662 instead of an ICL7660.
Although looking at the ICL7662 datasheet, I cannot see anything which explicitly states that it won't run at 1kHz.

What is the logic levels of the 7660 clock coming from the Nano?

In experiments with mu HH2 board I found that a 5V logic clock worked but when using a processor with 3.3V logic the 7660 would not clock. Solution was to use a transistor to level shift to a 12V clock into the 7660.
Maybe this is the issue.

[lc516]

What is the logic levels of the 7660 clock coming from the Nano?

In experiments with mu HH2 board I found that a 5V logic clock worked but when using a processor with 3.3V logic the 7660 would not clock. Solution was to use a transistor to level shift to a 12V clock into the 7660.
Maybe this is the issue.

Nano I/O output 5v, I can get -5v on TP3 when there are no other components.

[Qiaozhi]

What is the logic levels of the 7660 clock coming from the Nano?

In experiments with mu HH2 board I found that a 5V logic clock worked but when using a processor with 3.3V logic the 7660 would not clock. Solution was to use a transistor to level shift to a 12V clock into the 7660.
Maybe this is the issue.

The processor is outputting a 5V sync pulse, and the 7660 is operating with a 5V input.
Anyway, I think he has it working now.

[lc516]

Qiaozhi,Thanks for your information.

I used ultimate solustion, I'll open a new PCB make it and add components step by step.
[ATTACH]54941[/ATTACH]

Now,I can get -5v on TP3(ICL7662), I hope that goes well.

continue:

1 I add R1, ok,it's working well, TP3 get -5V.
2 add U3(NE5534P), TP3 get -3.8V
3 Replace with another NE5534P of a different brand, TP3 get -0.6V

I continued to add some components R7 r8 r9 r12, It was no change.

I was upset about the problem....

continue:
test the current of pin5 on 7660, it's 2.8mA.

[waltr]

Nano I/O output 5v, I can get -5v on TP3 when there are no other components.

The processor is outputting a 5V sync pulse, and the 7660 is operating with a 5V input.
Anyway, I think he has it working now.

Ok, great he has it working.
I wasn't sure what the Nano's Voltage levels are.
I didn't have issues with the 7660 on 5V logic.

[lc516]

Ok, great he has it working.
I wasn't sure what the Nano's Voltage levels are.
I didn't have issues with the 7660 on 5V logic.

Did you done the project?

I'm not sure,is the C2 and C3 can provide enough power in a clock cycle on 1K Hz?

[Qiaozhi]

Did you done the project?

I'm not sure,is the C2 and C3 can provide enough power in a clock cycle on 1K Hz?

With the PCB fully populated, coil connected, and running in Boost mode:
TP4 = +4.95V
TP3 = -4.70V

This project was originally developed by connecting an Arduino to a Surf-PI longboard. There was then a prototype PCB built, followed by this current version. None of these showed any problems with the 7660 generating the -5V supply. Andy (Silverdog) also built this version, as have others such as surfdetector.
Not sure what is going on with your build. Are you certain that you have a genuine 7660?

[lc516]

With the PCB fully populated, coil connected, and running in Boost mode:
TP4 = +4.95V
TP3 = -4.70V

This project was originally developed by connecting an Arduino to a Surf-PI longboard. There was then a prototype PCB built, followed by this current version. None of these showed any problems with the 7660 generating the -5V supply. Andy (Silverdog) also built this version, as have others such as surfdetector.
Not sure what is going on with your build. Are you certain that you have a genuine 7660?

I used icl7662 now, and I ordered a new one icl7660.

The TX is 50uS by default, I'll setup it on 100uS to test.

[Carl-NC]

Question: Is the frequency adjustment control we see on some pulse induction metal detectors really intended more for eliminating general external RFI, rather than specifically noise generated by power lines?

It's for whatever EMI aliases in, whether powerline or RF. Was it a high-tension line? The crackling you hear might be due to corona discharge which will create wideband noise.

[Qiaozhi]

It's for whatever EMI aliases in, whether powerline or RF. Was it a high-tension line? The crackling you hear might be due to corona discharge which will create wideband noise.

I've heard crackling noises from cables near high-tension pylons in damp weather, even without a metal detector, but this was a 240V overhead power line feeding a small group of houses.
I was just wondering why some PI detectors have a user-adjustable pulse rate, whereas others do not. From my own simple experiments I could not detect any difference in noise reduction when testing near a power line. However, I think I've answered my own questions by reading the White's TDI Pro Owner's Manual:

Frequency [control] - What it does.
This control makes small adjustments up or down to the transmitter pulse frequency or rate. This is used to counteract any interference which might be due to outside electromagnetic sources, such as radio stations, microwave, short wave, electric fences, power lines, lightening, electrical storms, or other metal detectors being used nearby. This interference is recognized by a warbling or pulsing of the audio threshold in a repetitive way, and can mask target signals. The Pulsescan TDI Pro has a frequency range of 3.25 kHz to 3.37 kHz pulses per second.

How to use it:
Electrical interference is not exclusive to urban areas, where power line harmonics, local radio transmissions, or microwave transmissions can raise havoc with the audio threshold. Getting too close to another metal detectors being operated, or electric fences, or invisible pet fences, will also cause this problem. A slight adjustment of the frequency control can help make the audio more stable.

[waltr]

Around here the power lines also carry Digital data. I have run into power lines that cause interference to my PI detector that sound broadband. Adjusting PI pulse rate will not cancel this type of EMI.

[lc516]

I think the problem is that you're using an ICL7662 instead of an ICL7660.
Although looking at the ICL7662 datasheet, I cannot see anything which explicitly states that it won't run at 1kHz.

I got a good voltage -4.9V on TP3 after I use the new ICL7660S.

I use oscilloscope to check the ICL7660S PIN7, It's have a normal waveform.

before, I got deform waveform on ICL7662 pin7, as picture

[Qiaozhi]

I got a good voltage -4.9V on TP3 after I use the new ICL7660S.

I use oscilloscope to check the ICL7660S PIN7, It's have a normal waveform.

before, I got deform waveform on ICL7662 pin7, as picture
[ATTACH]54949[/ATTACH]

That's good news.
Hope you receive the book soon.

[Krzysztof]

The tile has already arrived (nicely done), the book has not yet. Such a question: is the BOK list only in the book, have I not noticed it in the forum, or just read the values from the scheme?