Can pinpointer detecting thin chain?

[chemelec]

R2a may or may Not be needed.
Just depends on the Coil Windings.

Nupi mod by chemelec woks
I changed R2A 68k to 4k7 - my coil is 0.5mm wire and has lower resistances. C8 I threw out because the sound was strange -> https://youtu.be/DZ42f5ohKLA. Buzzer and led are powered by stabilizer LM1117 sot-223 and not directly from 9V. R2 is on pcb, R1 is available externally.

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[blobber]

You can regulate it by yourself with a 90° bend over screw near the coil for maximum sensitivity.
This works out in the field much better and faster as adjusting some variable resistor. Good luck!

That was a realy good idea, thankyou.
I use now the outer ring from a small old ball bearring, for fine adjustment, on my pinpointer from #599

[sinclairuser]

so I put this together but have encountered problems, its very chattery and unstable it does beep strongly on metal though, but things I noticed the 1k trimmer makes no difference when adjusting, the 100k does but it is right at the end of travel, its almost like it needs another couple of turns.
I have been reading this thread since the start, and going over it from the beginning have not found a post with my problems, its built on perf board like nupi's was.

[viwaldi]

What are the parameters of the coil? What is the resistance and inductance? It looks like the resistance was too large. If 100k is too small, add additional resistances in series.

[sinclairuser]

What are the parameters of the coil? What is the resistance and inductance? It looks like the resistance was too large. If 100k is too small, add additional resistances in series.

the inductance is- 1.70mh and 3ohms(coil1)
= =- 450uh and .6 ohms(coil2)

when testing inductance between 1+ and 2+ terminals the meter reads a combined total of 3.31mh and 3.6ohms
so not that far out but maybe could be tuned better, but I would have expected it to work.
its the pot adjustment not changing voltages that is driving me crackers.

[viwaldi]

I think that the L1 resistance is too large and you have a problem. Insert the 100k resistor as I wrote and check. Or change R2 to a larger one and also check.
I did chemelec's versions and the coil had smaller resistances. I had to greatly reduce R2A to work.
Images relate to the coil of post # 608. Nupi org and nupi chemelec work without any problems.

The C1 and C2 capacitors are also key. MUST be MKP.

[chemelec]

My caps were Not MKP.
Even Using Cheap Disk Caps, It worked for me.

[sinclairuser]

My caps were Not MKP.
Even Using Cheap Disk Caps, It worked for me.

yes chemelec, I don't think that is the issue i'm just not seeing the voltages I should be in the places I should, I have changed the regulator I case it was breaking down under load.
but get the same results, I am replacing the reg with a different type later, i'm wondering if the batch I have is knock off lol.
as I said its built on perf board as a lot of stuff I have built over the years, but if I cant get it running i'm going to bite the bullet and make one of the boards posted here, though I loathe etching, ferric chloride makes me ill, which is why I use perf board, maybe just starting again is a better strategy.

[Polymer]

yes chemelec, I don't think that is the issue i'm just not seeing the voltages I should be in the places I should, I have changed the regulator I case it was breaking down under load.
but get the same results, I am replacing the reg with a different type later, i'm wondering if the batch I have is knock off lol.
as I said its built on perf board as a lot of stuff I have built over the years, but if I cant get it running i'm going to bite the bullet and make one of the boards posted here, though I loathe etching, ferric chloride makes me ill, which is why I use perf board, maybe just starting again is a better strategy.

Don't worry about the perf board, it works just fine.
Funnily enough the first "quick & dirty" ones I built still work the best.
The "cleaner" ones I built later are not so good

I never got to solve the temperature issue, but am still using them in certain situations.

[chemelec]

yes chemelec, I don't think that is the issue i'm just not seeing the voltages I should be in the places I should, I have changed the regulator I case it was breaking down under load.
but get the same results, I am replacing the reg with a different type later, i'm wondering if the batch I have is knock off lol.
as I said its built on perf board as a lot of stuff I have built over the years, but if I cant get it running i'm going to bite the bullet and make one of the boards posted here, though I loathe etching, ferric chloride makes me ill, which is why I use perf board, maybe just starting again is a better strategy.

Use one part of Hydrochloric Acid to two Parts Hydrogen Peroxide.
Works BETTER Than Ferric Chloride and No Staining.

[6666]

C7 gets charged via R7, from top to bottom, and when it passes ~2.5V U3c and U3d toggle by means of a syncing circuitry. D3 accelerates discharging for the purpose of repetitive use. This circuit is a timer that switches from stabilising stage to the active stage.

Nupi, this schematic is built in ExpressSCH which is a freeware, and often used here.

Davor or anybody else, can you print the copper tracks to check for correct pad sizes etc and to make your own PCB when useing Express ?????

[Davor]

I left this project unfinished. In the meantime I discovered that this detector can be considerably more sensitive if oscillator voltage is rectified and as such used for detecting, but so far I left it unfinished.

[viwaldi]

New NUPI. Coil on ferrite from the anti-seize filter. Dimensions: 18 cm x 3.2 cm.

[Polymer]

Update on NUPI pinpointer, may be interesting for someone:

Yep, I just used this pinpointer for 5 weeks while abroad. It was an immense help.

BUT, I would change something which I was not aware of before.

I would NOT pot the search head (ferrite and wire) in epoxy again.

Why not?

Even light pressure when poking the pinpointer in the ground seems to mechanically couple to the ferrite sort of "bending" it & changing the magnetic properties.
This causes it to start beeping. Please note that this only happens when adjusted to very high sensitivity.

A possible solution I am going to try is to make a new coil and bed it in swim noodle foam and then put it in the nylon casing.
I hope this will mechanically decouple it from the outside of the search head more or less.

Cheerio

[viwaldi]

hi polymer
I had a similar situation - stirring the pinpointer under pressure. it was a ferrite wine. I bought ferrites from old radio antennas. the coil's housing was thick. she did not bend while searching. it was enough to change the ferrite and the pin started working normally. Wound the coil on OTHER Ferrite and check. you can use ferrite from an anti-seizing filter.