Arduino Nano PI Main Discussion

[godigit1]

Tried what I thing would be comparing a MPP vs a 1C integrator in Excel. First delay 4us for small nuggets. Hole is lower for MPP. Would expect MPP noise to be 4times higher with GB enabled. Peak noise is about 3times higher when I enable GB on my detector, so maybe a little less noise with a higher TC hole. Can attach excel program if anyone wants. Have in the past but might have made some changes.

Hi Green.
Sorry for the delay in posting health went down again.
I would like your excel program if you would, It will be another learning curve but that's what keeps me going.

Got my boards and will have parts complete soon.
Code is almost done I'm having a little trouble with the timing interrupts but almost ready to try in the IDE and see if it compiles.
I realize this is not the perfect platform to do GB but once the code is done the nanno can be applied to other designs.

Thanks again

[MartinB]

You made a good machine.
I also up running it,and not as good as yours.
I'll to improve it.

Watch Surfdetector's video on YouTube and set up the sample delay exactly the same for optimum performance. I also found that my coil was susceptible to EMI in my workshop so had to setup outside away from interference. Now I need to build a good coil. Good luck with your build.

[lc516]

Got my Arduino PI up and running today Just need to finish off the audio section.
Tried it on a Henry VIII silver penny and got a strong signal at 10 inches. For those of you who are not familiar with old English coinage, this particular coin is 14.5mm diameter and 0.65mm thick.
Thanks for a great project George

You made a good machine.
I also up running it,and not as good as yours.
I'll to improve it.

[MartinB]

Got my Arduino PI up and running today Just need to finish off the audio section.
Tried it on a Henry VIII silver penny and got a strong signal at 10 inches. For those of you who are not familiar with old English coinage, this particular coin is 14.5mm diameter and 0.65mm thick.
Thanks for a great project George

[surfdetector]

Here is my BOM. I have not built up my Nano Pi yet, as all the parts are in the mail, so I can not vouch for the accuracy of my list. Please take it with a grain of salt.

For those interested in getting everything from Tayda, here is the Tayda part number for a Nano: A-2864

[dingbatca]

Here is my BOM. I have not built up my Nano Pi yet, as all the parts are in the mail, so I can not vouch for the accuracy of my list. Please take it with a grain of salt.

Item	Name	Quantity	Tayda #
Arduino Nano	U1	1
ICL7660	U2	1	A-1051
NE5534	U3	1	A-250
CD4066	U4	1	A-555
LM358	U5	1	A-045
IRF9640	Q1	1	A-084
2N3904	Q2	1	A-111
2N3906	Q3, Q4, Q6	3	A-117
MPSA13	Q5	1	A-432
1N4148	D1, D2, D3	3	A-157
10K	R1, R5, R10, R11, R13-17	9	A-2203
Rd	R2	1
3R3 (2W)	R3	1
1K	R4, R6, R7, R21, R22, R28	6	A-2200
1M	R8	1	A-2277
22K	R9 R18, R27	3	A-2284
100k preset	R12	1	A-587
100K	R19, R26	2	A-2248
150R	R20	1	A-2199
220K	R23-R25	3	A-2329
47K	R29	1	A-2279
1000uF (Electro)	C1	1	A-4523
220uF (Electro)	C2, C3, C9	3	A-1159
100nF	C4, 5, 7 ,8 ,12 ,13 ,15	7	A-951
470nF	C6, C10-11, C14	4	A-568
10K pot	Sample delay, threshold	2	A-4879
1K pot	Volume	1	A-3556
Boost switch - On/Off		2	A-4567
2-pin screw term		4	A-1189
3-pin screw term		3	A-1190
high-impedance speaker
2-8 socket		3	A-001
2-14 socket		1	A-004
3X 18650 case		1	A-5393

[Qiaozhi]

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?

The Component Parts List is in Appendix A of the book.

[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?

[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.

[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

[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.

[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.

[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.

[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.

[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?