Bipolar PI design

[Orbit]

You will never be able to match the P and N drive of a half-bridge driver. To get the Rds to match, the PMOS needs to be much larger than the NMOS. Then the parasitic capacitance of the PMOS will be much larger and the damping will be different for the P & N. You can fake it somewhat by adding series resistance or extra capacitance to the FETs.

Series resistance didn't prove to be an ideal solution maybe mosfet capacity!?

[Altra]

You will never be able to match the P and N drive of a half-bridge driver. To get the Rds to match, the PMOS needs to be much larger than the NMOS. Then the parasitic capacitance of the PMOS will be much larger and the damping will be different for the P & N. You can fake it somewhat by adding series resistance or extra capacitance to the FETs.

Very true. You can get close enough to be usable.

[Detectorist#1]

Serious conversation is how the difference in Rds on and Cds between P-ch and N-ch transistors will affect the real work in practice. It is good to make this:
1. Adding of external resistors (this reduce the difference). The resistor in drain of N-ch transistor have to be with higher resistance.
2. Adding of capacitor in parallel to TX coil.
3. Use serially connected fast diodes with very low capacitance in series of the transistors
All these thinks have to seriously reduce imbalance. Maybe some one have possibility to analyze these ideas with good software simulator.

[pechkata]

Serious conversation is how the difference in Rds on and Cds between P-ch and N-ch transistors will affect the real work in practice. It is good to make this:
1. Adding of external resistors (this reduce the difference). The resistor in drain of N-ch transistor have to be with higher resistance.
2. Adding of capacitor in parallel to TX coil.
3. Use serially connected fast diodes with very low capacitance in series of the transistors
All these thinks have to seriously reduce imbalance. Maybe some one have possibility to analyze these ideas with good software simulator.

Hello detector #1
This is taught in first grade.
You're posing like a fairground vendor.

[pechkata]

For the half-sine the TX clocks are identical to the bipolar PI:



For the Impulse waveform the TX clocks are this:

Thanks Carl-NC
Whoever can, helps.

[pechkata]

Greetings to all readers of this forum.

[Detectorist#1]

Hi pechkata,
Тhose who know doubt, those who do not know are certain.

[algan]

Hi, Carl, can you take a look at whether this source code will work correctly for half-sine, I made it for PIC16F18426

[Carl-NC]

Hi, Carl, can you take a look at whether this source code will work correctly for half-sine, I made it for PIC16F18426

It looks like you are creating 10 positive pulses followed by 10 negative pulses. Half-sine recycles energy and requires alternating a single positive pulse with single negative pulse.

[boilcoil]

Maybe so?

PS:I don't know physically how the individual levels of PCLK1, NCLK1... correspond to the schematic diagram, so I have simply accepted them from the description of the published source code.
Perhaps, if they refer to some of traditional schemes, the ON should be SET, the OFF should be CLR

[boilcoil]

Excuse me, now I read that it is a half-sine wave, so I am correcting myself.

[pechkata]

I'll do that next time I sit to deal with it.

Hello ivconic
What happened, bro?
Where did you run away - you're not there?
The forum is not the same without you.

[pechkata]

Special greetings to ivconic

[ivconic]

I'm on the forum every day.
But I have nothing useful to contribute to the current thread, therefore I am silent.
My Bipolar PI is waiting. Until I put the 74HCT4053; I will not be sure about the next steps.
In the meantime I've beefed up my arsenal with the Vanquish 540 and my current thoughts are in that direction.
Regarding Carl's Bipolar PI from the ITMD3 book... this detector has something I haven't seen before in other detectors in a similar category; phenomenal behavior regarding GEB.
Another project from the book; The PI-GB design has virtually no reason to exist. I see no purpose... except for educational purposes.
I think that Bipolar PI needs to be further improved only in the part of the audio behavior and possibly a little more power of "penetration" (read as "increase in depth").
As it is now; it is good for use with very small coils (20cm and below) and on very "heavy" soils.
It is good for medium and larger coins in soils that are too mineralized for other detectors.

[Carl-NC]

The PI-GB design has virtually no reason to exist. I see no purpose... except for educational purposes.

That's the purpose of every circuit in the book.