Arduino Nano PI Main Discussion

[waltr]

I am happy to report I got my Nano PI running!

Now I am off trying to build a higher performance coil. I have the fast coil article that I have read through multiple time. I started off with a basic round coil, per the book. Then built two elliptical coils, and lastly I tried my hand at making a basic basket coil. Got the basket correct on the secound try. But none of these seem to respond all that much faster. All my coils are right around 18~20uS response time. I have always aimed for the same specs 300~400uH, and I have hit that range every time. Using a spool of 26awg magnet/speaker wire. I know Teflon insulation should help, but I am currently working with what I have. Happy to invest in the better wire, once I have the basic coil building technique hammered out.

Any advice to improve response time?

Pics attached.

That looks like the pre-amp recovery time. The NE5534 is not known to recover from output overloads very quick.
This subject has many threads and some solutions that improve pre-amp recovery time. The most common is a two stage pre-amp.

[dingbatca]

Fascinating, from a relative newbie, such as myself.

I hooked my same coils up to the Voodoo and found most of my coils were around 13~20uS. But the basket came in at solid 9uS! That scoots!!

Jumping WAY off the deep end. Could I borrow the TX and pre-amp circuit from the Voodoo, and replace them on the Nano PI (on a proto board)? Frankenstein PI?

[waltr]

Fascinating, from a relative newbie, such as myself.

I hooked my same coils up to the Voodoo and found most of my coils were around 13~20uS. But the basket came in at solid 9uS! That scoots!!

Jumping WAY off the deep end. Could I borrow the TX and pre-amp circuit from the Voodoo, and replace them on the Nano PI (on a proto board)? Frankenstein PI?

Good trying the VooDoo with a 2 stage pre-amp. 9us is good. On my HH2 I was able to get an IB DD coil down to about 11us using a single NE5534 pre-amp.

Yes, you can use the VooDoo pre-amp on this Nano project. You may need to adjust gains but this is easy.
George did this Nano project simply for everyone to get started using a processor and experimenting. He didn't do much with the analog circuits.

[dingbatca]

Good to know. I will hijack the Voodoo's TX and pre-amp circuit and jumper it into a Nano PI and see what I come up with.

[MartinB]

I am happy to report I got my Nano PI running!

Now I am off trying to build a higher performance coil. I have the fast coil article that I have read through multiple time. I started off with a basic round coil, per the book. Then built two elliptical coils, and lastly I tried my hand at making a basic basket coil. Got the basket correct on the secound try. But none of these seem to respond all that much faster. All my coils are right around 18~20uS response time. I have always aimed for the same specs 300~400uH, and I have hit that range every time. Using a spool of 26awg magnet/speaker wire. I know Teflon insulation should help, but I am currently working with what I have. Happy to invest in the better wire, once I have the basic coil building technique hammered out.

Any advice to improve response time?

Pics attached.

That is a pretty cool coil jig you have there. What are the plastic pegs?

[MartinB]

Thanks,
It seems that these problems are due to the fact that my book has not been received.

Take a look at Surfdetectors series of videos on YouTube. Very helpful.

[dingbatca]

MartinB. My coil wrapping jig is just a simple pattern cut out with my CNC. I designed and 3D printed the pegs as part of the jig. My 6yr old daughter picked the peg color. Some fun pic's attached.

[gallico58]

Hello
I made arduino nano PI as per book and it works very well, I use a 250uh coil and it has good depth.
I wanted to improve it and know if it was possible to disable the unused analog inputs via software in order to further reduce the disturbances that sometimes occur.
the entrances left free often pick up disturbances.
great project George thank you

[mschmahl]

I am happy to report I got my Nano PI running!

Now I am off trying to build a higher performance coil. I have the fast coil article that I have read through multiple time. I started off with a basic round coil, per the book. Then built two elliptical coils, and lastly I tried my hand at making a basic basket coil. Got the basket correct on the secound try. But none of these seem to respond all that much faster. All my coils are right around 18~20uS response time. I have always aimed for the same specs 300~400uH, and I have hit that range every time. Using a spool of 26awg magnet/speaker wire. I know Teflon insulation should help, but I am currently working with what I have. Happy to invest in the better wire, once I have the basic coil building technique hammered out.

Any advice to improve response time?

Pics attached.

If you want a fast coil, you have to use the extensions from the coil-wire as cable between coil and detector.
If you solder in an extra cable you have to use a low capacitive cable.
Try to make the coil on the min. specs near 300 uH to reduce response time.

[Qiaozhi]

Hello
I made arduino nano PI as per book and it works very well, I use a 250uh coil and it has good depth.

Glad to hear that you achieved a good result.

I wanted to improve it and know if it was possible to disable the unused analog inputs via software in order to further reduce the disturbances that sometimes occur.
the entrances left free often pick up disturbances.
great project George thank you

I'm not sure if that would make any difference, as noise will only be a problem if they are being used. But you could try setting the unused analog pins as digital outputs, and then drive them with a permanent LOW.

For example:
pinMode(A1, OUTPUT);
digitalWrite(A1, LOW);

Alternatively, you could simply pull the analog inputs HIGH using the internal pull-up resistor.

For example:
pinMode(A1, INPUT_PULLUP);

[gallico58]

Thanks George, in fact I have modified the software but nothing changes, approaching the minimum without saturating U3 the repetitive interference capture threshold seems dependent on the nano.
still nice project to try.
I am attaching two images, channel A pin6 U3 (inverted) Channel B pin13U4.4. minimum and maximum main sample adjustment

[Qiaozhi]

Thanks George, in fact I have modified the software but nothing changes, approaching the minimum without saturating U3 the repetitive interference capture threshold seems dependent on the nano.
still nice project to try.
I am attaching two images, channel A pin6 U3 (inverted) Channel B pin13U4.4. minimum and maximum main sample adjustment
[ATTACH]55065[/ATTACH] [ATTACH]55066[/ATTACH]

I should imagine that any interference is external. The Nano is not being used to detect the threshold, as this is part of the analog circuit.

[MartinB]

MartinB. My coil wrapping jig is just a simple pattern cut out with my CNC. I designed and 3D printed the pegs as part of the jig. My 6yr old daughter picked the peg color. Some fun pic's attached.
[ATTACH]55058[/ATTACH]
[ATTACH]55059[/ATTACH]
[ATTACH]55060[/ATTACH]

I am a little envious of your workshop.
Tell your daughter that she has good taste. Pink and purple pegs look great and such a simple idea too.

[Olly]

After following the book to the letter I'm happy to report that my Nano PI is working very well indeed.
Many thanks Qiaozhi for your excellent design and well written, easy to follow instructions and guidelines.
Also many thanks to Silverdog for providing the high quality PCB's with such a short turn-around time; I'm most grateful.

Now that everything is working correctly I'd like to make it look a little bit more professional and was wondering where folks in the UK source such things as detector stems and coil housings at a reasonable price?

[MartinB]

After following the book to the letter I'm happy to report that my Nano PI is working very well indeed.
Many thanks Qiaozhi for your excellent design and well written, easy to follow instructions and guidelines.
Also many thanks to Silverdog for providing the high quality PCB's with such a short turn-around time; I'm most grateful.

Now that everything is working correctly I'd like to make it look a little bit more professional and was wondering where folks in the UK source such things as detector stems and coil housings at a reasonable price?

Hi Olly
Good to hear that you are up and running.

It all depends on how much you want to spend, how much spare time you have, and what facilities you have.

Shafts: Any of the major suppliers should be able to sell you one. Try Regton or Joan Allen. There is also a system by MARS which can be found on Ebay. I am making my own from 3D printed parts and carbon fibre tube obtained on Ebay.

Coil Housings: First of all try dbanner who regularly posts on the forums. Lives in America andproduces excellent housings. I did find a guy in Russia selling on Ebay but I don't know what the current situation is. Delivery times are really long. You could of course make your own, but you will need a vacuum forming machine and a little patience. There is lots of information about this on the internet and no doubt within the forum. I tried the oven method of heating the ABS sheet and failed miserably so I built a simple vacuum forming machine. ABS sheet is available on Ebay 2 mm Black Carbon Fibre Effect ABS Sheet, larger sizes 400mm-500mm-600mm-widths | eBay.

Cost of buying ready made is slightly more than DIY but not half as much fun.

Happy to share with you.