Bipolar PI design

[eduardo1979]

Hello.
Yes, GND and -5V.

[h9361]

The TDI with the GB ON (at number 8 ) detects the nugget at 10 cm. The Bipolar PI with the GB off detects it at 3 cm, and with the GB potentiometer halfway through the range, right where the hot stone is rejected, the nugget is detected at 1 cm. I'm surprised that the TDI, with the GB in any position, doesn't lose depth for the 0.5 g gold nugget, and the Bipolar PI loses depth when changing the GB value. I understand that both detectors have subtractive GB, but in different configurations. I've tried modifying the GB on the Bipolar PI to match the TDI, and it doesn't work. There's no way to reject the stones. I've put a 1 Mohm potentiometer on the GB to get a good adjustment range, and it doesn't work either.
Any ideas, Carl?
I've attached the schematic of my circuit, the one shown in the video, in case it helps anyone.

Hello
Dear eduardo
I have a question about your schematic (audio part).
Is the P5 (threshold) connected to Ground and -5V?
Thanks

[Laith]

In Bipolar PI Rev 2.1 build, using IRF9630 for Q1/Q2 and IRF740 for Q3/Q4. Since the PCB layout is very tight, is it mandatory to use heatsinks for all four MOSFETs? Will the heat build-up cause frequency drift or affect the threshold stability and ground balance during extended use?"

[sayan1345]

Hello Mr Carl thank you very much
I couldn't find PIC16F18426
Can I use PIC16F84 instead of PIC16F18426?
also I couldn't find max412

[sayan1345]

Hello GeoMax
proteus

[GeoMax]

Hello Sayan1345,

what electronic design software are you using to design your PCB?

[Carl-NC]

The 4066 has 14 pins, the 4316 has 16 pins. They are pin-compatible except for the 2 extra pins. You can use the 4066 in the Bipolar PI design but you will need to add level translators to the micro. I think that was previously discussed in this thread.

[sayan1345]

thank you very much
I downloaded datasheet for both IC

[GeoMax]

Hello Sayan1345,

You need to compare the datasheets for the two components (CD4066 and 74HCT4316) to ensure they are pin-compatible. If not, please check that you have connected them correctly on your board, as shown in the datasheet. You can find both datasheets online. Just search for them on Google.

[sayan1345]

Hello Mr. Karl, please help me build this project. There is no 74HCT4316 IC in our country.
thank you for this project

[sayan1345]

hi all Member of forum
please this PCB is correct for CD4066 or no ?

[Laith]

Everything is here:
https://www.geotech1.com/forums/foru...olar-pi-design

Thanks a lot

[Carl-NC]

Any one can give me the parts list

Everything is here:

https://www.geotech1.com/forums/forum/inside-the-metal-detector-aa/itmd3/pi-designs/430863-bipolar-pi-design

[Laith]

The diagram is in the forum. You have to read the thread from the beginning and stop at my last post.

Is it ready to get it out in the field

[Laith]

Any one can give me the parts list