Can pinpointer detecting thin chain?

[Qiaozhi]

Szia! Saját mutató.

https://www.youtube.com/watch?v=LrEy-YcM-i8

Please read the forum rules -> Basic Rules of the Forums
and make your posts in English.

[Nupi]

Szia! Saját mutató.

https://www.youtube.com/watch?v=LrEy-YcM-i8

Nicely done.

[Waikiki_Sweep]

OK! Instead of VLF lets name it audio frequency coil, audio frequency metal detector and so on. Terminology is not much important, understanding is.

I like Nupi pinpointer !!!!!!

[hadrianus]

Szia! Saját mutató.

https://www.youtube.com/watch?v=LrEy-YcM-i8

[chemelec]

Designation		Frequency	Wavelength
ELF	extremely low frequency	3Hz to 30Hz	100'000km to 10'000 km
SLF	superlow frequency	30Hz to 300Hz	10'000km to 1'000km
ULF	ultralow frequency	300Hz to 3000Hz	1'000km to 100km
VLF	very low frequency	3kHz to 30kHz	100km to 10km
LF	low frequency	30kHz to 300kHz	10km to 1km
MF	medium frequency	300kHz to 3000kHz	1km to 100m
HF	high frequency	3MHz to 30MHz	100m to 10m
VHF	very high frequency	30MHz to 300MHz	10m to 1m
UHF	ultrahigh frequency	300MHz to 3000MHz	1m to 10cm
SHF	superhigh frequency	3GHz to 30GHz	10cm to 1cm
EHF	extremely high frequency	30GHz to 300GHz	1cm to 1mm

However, to simplify things about VLF a good idea would be to use term audio frequency range. Imagine doing a project covering 20 Hz to 20 kHz, it would be annoying to write ELF/SLF/ULF/VLF all the time. But again it would not be correct if you just write VLF because there is much more in that range. Right? Instead, simply use term 'audio frequency range'. As I said in the beginning there are already dozens of articles with wrong frequency designations and a good thing would be to correct and minimize mistakes.

[Nupi]

Simulation shows 15kHz. IMHO it would be beneficial to go up with frequency. In that case you should consider going for pins 4 and 9 instead 5 and 11. Right now the sound is a bit irritatingly high, so maybe 4 and 6 would be ideal with elevated frequency.
I made it work in LTspice the way it behaves in real life, only I did not hit the sweet spot with the working point yet. I think the feedback could be cranked up a bit to promote the super regenerative behaviour, because it does look that way. That would explain a lot about the sensitivity.
I also discovered that emitter degeneration resistor is a far more responsive component to tweak the sweet spot. Maybe this design would benefit ftom some serious bias redesign, but don't worry, it will remain simple.
Yeah, this is interesting!

Thank you very much for explanation and effort.
It is a simple but effective circuit.
I am very fascinates how much improvement you can make.
I'm going to bed. Maybe I speak you tomorrow.

[Davor]

Simulation shows 15kHz. IMHO it would be beneficial to go up with frequency. In that case you should consider going for pins 4 and 9 instead 5 and 11. Right now the sound is a bit irritatingly high, so maybe 4 and 6 would be ideal with elevated frequency.
I made it work in LTspice the way it behaves in real life, only I did not hit the sweet spot with the working point yet. I think the feedback could be cranked up a bit to promote the super regenerative behaviour, because it does look that way. That would explain a lot about the sensitivity.
I also discovered that emitter degeneration resistor is a far more responsive component to tweak the sweet spot. Maybe this design would benefit ftom some serious bias redesign, but don't worry, it will remain simple.
Yeah, this is interesting!

[Nupi]

Tomato fits better in ferrite ring or cap. You should try bigger diameter core and you will see some distance increasing.

I like the idea of long range pinpointers like yours because in many cases you can pinpoint target from the surface.

With regular pinpointer you have to dig holes an poking your pinpointer into it all the day.

You are absolutely right.

[Waikiki_Sweep]

I was planning to sale Carl this High End Coil for the TRX,
I changed my mind because I think he will find it too expensive.

What do you think?

Tomato fits better in ferrite ring or cap. You should try bigger diameter core and you will see some distance increasing.

I like the idea of long range pinpointers like yours because in many cases you can pinpoint target from the surface.

With regular pinpointer you have to dig holes an poking your pinpointer into it all the day.

[Nupi]

I was planning to sale Carl this High End Coil for the TRX,
I changed my mind because I think he will find it too advanced.


What do you think?

[Nupi]

[QUOTE=Waikiki_Sweep;187165]Formally it is audio but I am not sure I can hear 16 kHz freely in my age, my daughter sure can. ..........QUOTE]

And my dog too!!

I have not seen him for days.

[Waikiki_Sweep]

16 Khz is in the Audio Range.

Formally it is audio but I am not sure I can hear 16 kHz freely in my age, my daughter sure can.

Wikipedia:[Very low frequency or VLF refers to radio frequencies (RF) in the range of 3 kHz to 30 kHz and wavelengths from 10 to 100 kilometres.]

Metal detectors working in VLF frequency range are able to penetrate ground better. Metal detector or pinpointer working on 100 kHz will loose more signal strength in the ground.

Also 16 kHz is good to find small gold targets. Lower frequencies are used for bigger or more conductive targets.

That is why 16 kHz Nupi pinpionter especially good to find small gold!

Some examples of VLF metal detectors frequencies:

Whites Spectra V3 uses three frequencies – 2.5 kHz, 7.5 kHz and 22.5 kHz.
Minelab Excalibur sends out 17 distinct frequencies ranging from 1.5 to 25.5 kHz.
Fisher CZ has two frequencies 5 and 15 kHz.
Garrett ACE 250 metal detector has an operating frequency of 6.5 kHz.
Fisher F2 runs at 5.9 kHz.
Fisher F5 - 7.8 kHz.
The AT Pro is in the 15 kHz range.
Tesoro Vaquero is around 14 kHz.

[Nupi]

16 Khz is in the Audio Range.

Yes that's right.

[chemelec]

16 Khz is in the Audio Range.

[Nupi]

My wife says I make terrible mess.
I think she exaggerates.

My other hobby has to wait.