Pinpointer technical issues

[getsa]

Hello everyone, and happy new year!

Does anyone know if there is a pinpointer circuit that is analog and has automatic sensitivity adjustment?

I made two different project successfully - Minimax and Nupi and I got excellent results, but... Minimax doesn`t have static/non-motion mode of operation, and Nupi`s sensitivity needs to be adjusted manually constantly.

It would be good, if there is such a useful project, no matter how complex the scheme is.

Or if there are workable solutions already achieved by someone, in which the above mentioned deficiencies of the cited pinpointers are solved?

Greetings!

[GeoMax]

Hi Getsa,

can you post the two pinpointer circuits you built here? Maybe people are interested to make them too and/or give you hints
how to modify the circuits for static/non-motion mode.

[getsa]

https://www.youtube.com/shorts/Tnj76--DixU, it was shared in #662 / https://www.geotech1.com/forums/foru...n-chain/page45


Also, I have very good results with minimax pinpointer- unfortunately, currently I am difficult to find the video in my PC...

[Aleks85]

Hello getsa, I have such pinponter schemes, but you will understand the descriptions - I am sure.
С уваженим Саня.
https://drive.google.com/drive/folde...usp=drive_link

[getsa]

Thank you Aleks.

I'll take a look at the schematics later today.

Regards!

[Detectorist#1]

Hi Getsa,

I have schematic of non motion analog pinpointer with stable work. This schematic allow to made non motion PI detector with larger coil for bigger and dipper targets with some changes in resistors concerned with the coil.
Attached is the schematic.

[Detectorist#1]

Hi Getsa,
This solution answers to all your requirements:
1. Analog solution
2. Automatic sensitivity - have logarithmic response to useful signals
3. Non motion solution - the signal on the output of the end of amplifying stages changes only with 25mV after 5 minutes stop of the coil over the target
4. Use only 5 IC - you mention - no matter how complex is

[Detectorist#1]

Hi Getsa,

Attached is the new version of the schematic with increased "HOLD" time of DC voltage correction part.

[getsa]

Thank you for sharing. I will examine it in more detail later.
Has this schematic been made for real? And if yes - what are results?
Regards!

[Detectorist#1]

8 pcs are made and the stable results are:
0.5 grain Pb ball - 0.5 inch
1gran Pb ball - 1 inch
25c USA - 2 inches
This project was specially optimized for under grain application.

[JoyJo]

Hi Getsa,

Attached is the new version of the schematic with increased "HOLD" time of DC voltage correction part.

Tell me, please, how is the pinpoint antenna made? Can you show a photo of how the coil is made?

[Detectorist#1]

Hi JoyJo,

As per pdf file ( left down part of the picture), the antenna consists 31.5tours of 0.4mm magnet wire over one end of 20mm PVC tube with length of 60mm.
Experiments points that low diameter wire have higher resistance and peek current of 8A is not achieved. And wire with bigger diameter is recognized as target and the min delay increase.
0.4mm is "the golden middle" as diameter.

[JoyJo]

Did I understand correctly that the winding takes place in one layer (only winding on a plastic tube) Is the antenna manufactured without a ferrite core?

[Detectorist#1]

Yes, winding is in one layer. No ferrite core. Any adding of ferrite core is recognized as target and min delay increase seriously.

[Detectorist#1]

Adding of ferrite core transfer the pinpointer from sub-grain target recognizer to coin's recognizer.