Arduino Nano PI Main Discussion

[Jeg]

Thank you George. Yes I also suspect that my 7660 Ic's are not genuine. I am waiting for new ones to arrive. About Arduino i suspect that i over feed it accidentally and i made a damage on the board. I ordred a new one to continue.

[Qiaozhi]

Hi all
George i encounter an issue here in relation with 7660. More specifically i used an ICL 7660 ACPAZ. It doesn't work. Output is zero instead of negative. I changed it with a second one i had in hand of the same type and again no output. Few pages back there was also one more builder having the same issue. Is there any specific type that i need to purchase?

Arduino is getting too hot. Have you noticed that? A laser temp meter shows 57 degrees C. Looks like its coming from the internal voltage regulator.

Very elegant job, thanks a lot for sharing. I started soldering without having the book yet and it was difficult enough for me. Especially when i first soldered the parts and then noticing the small hole links between the two layers!!!

So far so good!

Hi Jeg,

Sorry for the late reply. I've been away getting some summer sun. Back to reality now and -4 degrees C.

You can use any ICL7660 or even an LT1054. I suspect you have a bunch of fake devices.
Also, the Arduino should not be getting hot.

[Emersonpaz]

The value of the damping resistor is based on all the capacitance that the coil sees. It comes from these primary sources.
1. Coil turn to turn capacitance
2. Coil to shield capacitance
3. Coil coax cable capacitance.
4. MOSFET COSS

The damping resistor is actually damping the capacitive energy that occurs when the TX discharge pulse drops and then starts to oscillate. Reduced coil seen capacitance allows a higher damping resistor value to be used and allow a steeper discharge pulse slope that more efficiently stimulates low TC targets.

Go to the articles section of this forum and go to projects to see the article I wrote in 2006, Making a fast PI mono coil for more detailshttps://www.geotech1.com/cgi-bin/pag...oils/index.dat.

The easiest way to make a faster coil is to use coil wire insulation with a low dielectric constant such as Teflon. Put a diode in series between the MOSFET and the coil to minimize the MOSFET COSS that the coil sees. Use the shortest and lowest capacitance coax cable that you can find.

I hope this helps.

Joseph J. Rogowski

Thanks my friend

[Jeg]

It doesn't heat up, it works normally. the only time it got hot was when i reversed the polarity i remember the fried atmel got too hot i had to change the nano v3

Thank you brother, i'll check the routing again even if i am preaty sure that everything is wired right. I can even scope the 1Khz pulses at Arduino's output.

[bbsailor]

I found the damping value to be low, I used a ready-made coil that I had

https://youtu.be/JTpd229ys5Q

145 ohms resistor

The value of the damping resistor is based on all the capacitance that the coil sees. It comes from these primary sources.
1. Coil turn to turn capacitance
2. Coil to shield capacitance
3. Coil coax cable capacitance.
4. MOSFET COSS

The damping resistor is actually damping the capacitive energy that occurs when the TX discharge pulse drops and then starts to oscillate. Reduced coil seen capacitance allows a higher damping resistor value to be used and allow a steeper discharge pulse slope that more efficiently stimulates low TC targets.

Go to the articles section of this forum and go to projects to see the article I wrote in 2006, Making a fast PI mono coil for more detailshttps://www.geotech1.com/cgi-bin/pag...oils/index.dat.

The easiest way to make a faster coil is to use coil wire insulation with a low dielectric constant such as Teflon. Put a diode in series between the MOSFET and the coil to minimize the MOSFET COSS that the coil sees. Use the shortest and lowest capacitance coax cable that you can find.

I hope this helps.

Joseph J. Rogowski

[Emersonpaz]

It doesn't heat up, it works normally. the only time it got hot was when i reversed the polarity i remember the fried atmel got too hot i had to change the nano v3

[Jeg]

Nice job emersonpaz. Does your arduino gets hot?

[Emersonpaz]

I found the damping value to be low, I used a ready-made coil that I had

https://youtu.be/JTpd229ys5Q

145 ohms resistor

[Jeg]

Hi all
George i encounter an issue here in relation with 7660. More specifically i used an ICL 7660 ACPAZ. It doesn't work. Output is zero instead of negative. I changed it with a second one i had in hand of the same type and again no output. Few pages back there was also one more builder having the same issue. Is there any specific type that i need to purchase?

Arduino is getting too hot. Have you noticed that? A laser temp meter shows 57 degrees C. Looks like its coming from the internal voltage regulator.

Very elegant job, thanks a lot for sharing. I started soldering without having the book yet and it was difficult enough for me. Especially when i first soldered the parts and then noticing the small hole links between the two layers!!!

So far so good!

[fathallah]

very thanks surfdetector .ok iwill check your videos . i am one of your followers.

[Jeg]

Thanks surfdetector. Your vids are wonderful.

1) The jig: https://www.youtube.com/watch?v=CrJ5tFFmWyo
2) How to: https://www.youtube.com/watch?v=Gr__N4_k2Mc

[surfdetector]

Please what is the measurement of the Resistance R2 ?

R2 is the Damping Resistor. You need to figure that measurement out with the use of a damping resistor jig and your oscilloscope. I have videos on my Youtube channel that show the procedure.

[fathallah]

Please what is the measurement of the Resistance R2 ?

[Jeg]

A big frame coil will need a slow self-adjusting threshold (SAT), so you will most likely need to adjust the values of C14 and R25 to slow down the response.
Also, detectors with big frames coils usually have fairly low TX pulse rates and longer TX pulse widths. This can be adjusting by modifying the software.

Great George, can't wait for the board and components to arrive. I'll figure out a way making those adjustments externally depending each time of the coil i use. I found a nice aluminum case to enclose the contraption, and i have already made my frame coil 1,2m X 1,2m. I'll post related info when ready!

[Qiaozhi]

Hi all
Qiaozhi what is your opinion about big frame coils in relation with the ANPI? Does it behave good in slow movement?

Thanks

A big frame coil will need a slow self-adjusting threshold (SAT), so you will most likely need to adjust the values of C14 and R25 to slow down the response.
Also, detectors with big frames coils usually have fairly low TX pulse rates and longer TX pulse widths. This can be adjusting by modifying the software.