Bipolar PI design

[Detectorist#1]

The solution - desolder all resistors and sold them in right direction! But not today. We have to believe in tomorrow's day!

[Detectorist#1]

Now seriously,
Ivconic, for your dream for good MD, capable to finding small coins, with good GB possibilities, not with very deep possibilities, maybe mechanically stable coplanar PI-IB coil will do this work. All we, DIY peoples, have to make additional efforts for achieve this dream.

[eduardo1979]

I totally agree with you, Detectorist #1. My next project will be a hybrid detector with an IB DD coil. I'm about to buy a Hybrid Pulse from Mikron Bulgaria to see how it works and maybe improve it. I'm sure we could solve the ground balance issues with this detector together with an LM393 comparator. I have a friend here in Spain, in a city called Huelva, who has a detector like this, and he told me that it's practically impossible to search in real ground with this detector. The ground balance is impossible to adjust; you'd have to adjust the ground balance every step you take. Anyway... it's a long story, and I don't like to go into too much detail.

[Orbit]

Do you think of the Smart hybrid that often adjust the geb? I don't believe you can copy it, it's a flooded processor and lines to the demodulator. And the commercial detector that is still being sold would be theft, Mikron could sue you.

[Detectorist#1]

Hi eduardo1979,
Maybe Carl will help to us to design hybrid PI detector with stable GB. In the meantime, we will work on this.

[Detectorist#1]

Hi eduardo,
In the long discussion in bulgarian site "metaldetecting.eu" (from 2023), the author of "Micron Hybrid Smart Pulse" said that this project from the beginning is for middle size objects - preferably coins. He mention that if this project will be modified for small nuggets, the results will be not better than other good detectors.

[Carl-NC]

I think the main problem on my detector is that I soldered all the resistors backwards!

That'll make all the currents go backwards. On the bright side, it will charge your battery.

[ivconic]

I knew something good would eventually come out of this!

[pechkata]

I knew something good would eventually come out of this!

https://www.youtube.com/watch?v=pMRQRCv3WwE

[pechkata]

Continuation:

https://www.youtube.com/watch?v=PADUImGg4Ic

[eduardo1979]

Very good videos!!!

[ivconic]

First, check that both demods are working correctly: IC5a should have a positive-negative target signal and IC5b should have a negative-positive target signal. If these look OK, then check the soldering of you GB pot, especially the pin to the ground channel.

Carl , I am lost, here is the video, go figure:

[Carl-NC]

If you are expecting a roll of solder to be a low conductor, it's not; it's a high conductor, just like the nail. Get some household aluminium foil and cut a 25cm square piece, use that for a low conductor.

[Detectorist#1]

Bravo pechkata! Very good result with home-made bifilar TX OO coil! I also work on bipolar MD with GB now.

[ivconic]

If you are expecting a roll of solder to be a low conductor, it's not; it's a high conductor, just like the nail. Get some household aluminium foil and cut a 25cm square piece, use that for a low conductor.

It makes sense.
In the previous videos you saw the behavior on coins.
It always behaves the same.
You didn't tell me your opinion about the voltage?
Is that how it should act?
I still have doubts about the quality and originality of these TL072s.