Polish Pi

[Emersonpaz]

I made the project VCO from mickstv I'm using it on the Polish pi https://youtu.be/RDV93ZdeGhk

[etznab]

What values can be used for R1?
I made the changes you said and it works very well ..
I would like to try the exchange of R-1 to have a further improvement. Another problem I am having is instability. the tec .tec noise. tec. gradually gets accelerated. Someone has already managed to solve this problem.

Have you managed to solve the problem of gradual acceleration? Is it instability? The same thing happens to me, it accelerates little by little "the tec tec tec...".
Tell us how to solve it. Thank you

[etznab]

[ATTACH]54603[/ATTACH]
[ATTACH]54603[/ATTACH] Green [ATTACH]54603[/ATTACH] Pin 10 4011
Yellow pin 5

Hi.

Im have a same scope hantek 6022BE. I have not put my probe at the output of the irf630 because it may be more than 400v, and I am afraid of burning my scope. Test leads are up to 10x. Have you put the tip on that exit? before the zener diode?. Is it safe to do it?. Thanks

[etznab]

I already have an oscilloscope Hantek 6022be and and inductance meter LCR VC6243A

I have made some modifications recommended in the geotech forum that are based on the original sandbanks document.
https://www.geotech1.com/forums/foru...4352-polish-pi

https://www.geotech1.com/pages/metde...ndbanks300.pdf
in this doc explain how to change de frecuency to 500hz

I also changed the decoupling capacitors to 100nf polyester capacitors, this is recommended by a Brazilian youtuber:
https://www.youtube.com/watch?v=dky04-GuYnY

i have the next modifications. This changes recolect the video of the Brazilian youtuber, sandbanks document and any recomendation of geotech user. I did not put the same values of sandbanks because the forum users consider the tolerances and values that the pi polones have to be different from the sandbanks
Brazilian youtube changes: electrolitic capacitors decoupling 10uf to 100nf. And add extra capacitor 100nf conecting pin 4 (IC3) and positive source
Sandbanks document changes: Response Speed: change the 220nf capacitor to 33nf (C2), change the 220nf capacitor (C11) to 100nf, change the 220nf (C13) to 100nf.
I have changed resistors to delay sample to detect gold: resistors R10 and R11. I think i changed to 18k, think. Sample delay: 25us

I left a resistance of 415ohms until it had the waveform mentioned in the sanbdbanks document. Pin 6 lf356 (IC1)



I have doubts about putting the probe in the signal return of the coil, before the zener diode, because I have seen that it is more than 400 volts and it can damage my oscilloscope, which allows 35 volts and only has a 10x attenuator probe. What do you think? I would like to put the probe there with a 1000x attenuation circuit to be able to calibrate in this way or will the previous IC1 waveform be enough?



Its work, I can detect a small women's gold ring at 14cm

Specs:
500hz
106us ( i change the 1k resistor R1 )
coil: 25cm diameter. 399uH

My modifications pic:

[Detectorist#1]

It is very old schematic without good possibilities - no EFE canceling and no possibility for small targets recovery.

[etznab]

my experience on two sample delay resistors:
i tried 20k for both (27uS sample delay) with a 50cm spiral flat coil about 350uH
detects gold very good but as soon as you try to go over some clean ground it does not work, too sensitive to capacitive effect of ground
have to shield it
but increase the resistors up to 27k both, it works like a champ
40uS delay if i remember correctly and very little ground effect
still catches gold
12gram bracelet 18k : 80cm
2gram ring 14k(not sure) : 17cm

I This past Sunday I went to a desert mountain area and probed with the detector my poles. Any problems: I calibrated the tac tac with the coil in the air, and then did it with the coil touching the ground (it accelerated a little and recalibrated the tac tac). But I realized that when I calibrated it with the tac tac it didn't detect a buried coin at 10cm. But when I calibrated the detector with the coil separated from the ground approximately 3cm it had more power and detected the coin that was 10cm buried and also with the coil 3cm separated from the ground. I mean 13cm. The problem is that when I lowered the coil to less than 3cm, for example 2cm, from the CLEAN ground WITHOUT ANY OBJECT, the detector reacted as if it were a target. And I read this comment from Mr.Jaick and I changed those resistors, I haven't gone to try it but as soon as I have the opportunity I will go if that fixes it. Another thing is that the damping resistance was slightly higher. It would have to be 390ohms, but I could only make resistance in series so that it gave me 415ohm. Coil 25cm 390uf.

I already put a different coil 12cm 360uf, this one fits well with the 415ohm damping resistance

Still catches gold in air

I haven't gone to test how it works yet, I'll go as soon as I have the chance.

[Detectorist#1]

Don't waste time and money on this project - it's not worth it. The projects: Barracuda, Minipulse Plus and Surf PI are on the same complexity but with more good parameters as targets size, deepness and EFE capabilities.

[etznab]

Don't waste time and money on this project - it's not worth it. The projects: Barracuda, Minipulse Plus and Surf PI are on the same complexity but with more good parameters as targets size, deepness and EFE capabilities.

Currently I have it manufactured and working, I want to get the most out of it possible with what I already have. If I had known these details before doing it I would have done the projects you mention. Now I just want mine to work at its best.

[Detectorist#1]

Hi etznab,
OK. It's your decision. But don't expect much. The real results on the real field (not air tests in room wаving the target - not the coil) will be very disappointing.

[GeoMax]

Hi guys,

has anyone checked the performance of the Polish detector called "RAMSTAR" on YouTube? Don't be surprised... inside is the basic circuit of the PI Polones! Last year I bought a used metal detector for a few dollars in the neighborhood. It was the Polish detector "RAMSTAR". I believe one of their first models. After opening the device, I was very surprised to see a slightly modified PI Polones detector inside. The son of the previous owner mentioned that this was his late father-in-law's beloved detector. The performance of this "RAMSTAR" detector was better and deeper than the Garrett ACE400 that his father-in-law had as a back-up detector. So watch the Youtube videos of the RAMSTAR detector and see what you can do with a "PI Polnes" (alias RAMSTAR). But I can well imagine that this detector is not made for Australian gold fields due to its simplicity.

[Detectorist#1]

Hi GeoMax,
It is interesting what are "slightly modifications" in original PI Polones MD. Maybe these modifications include EFE canceling and capabilities to find small nuggets.
Please, show us these modifications in the schematics.

[GeoMax]

The "slight modifications" are only an additional CD4011 and LM741 for reverse discrimination. No EFF cancellation.

[Detectorist#1]

What you mean under "reverse discrimination"? For EFE cancellation - one of my first attempts in PI MD was without EFE cancellation and worked very good in air home tests when the targets are waving, but when the targets are static and the coil is waved - the sensitivity have to be reduced 10 times for avoiding of false signals.

[GeoMax]

Hi,

for "reverse discrimination" this circuit below was added only. There is also a video of this modification on YouTube. The circuit below is a screenshot from this video.

[etznab]

What means EFE ?. Yesterday I did the tests in the field, burying objects. Yesterday I went to test the detector by changing the resistance of the pulse subtraction with the coil appropriate to the damping resistance that I have, and apparently it no longer reacts as much with the ground. But it still seems to lose a little depth. but I think it can improve