Bipolar PI design

[ivconic]

Come again! Oooops!
Wait!
I think we have something here!
Carl pay attention to this!
Boilcoil provoked me to observe this more carefully!
If the micro is powered from ground to negative rail... and the negative rail is "generated" via charge pump controlled by micro....!???
How about that!?!

This is no longer valid.

[boilcoil]

About 4066 I'm not sure...
Thanks!

Hi ivconic,
Sorry to interfere with your project, but just look at this:

[ivconic]

Hi ivconic,
Sorry to interfere with your project, but just look at this:

Feel free to "interfere" as much as you want.
The idea is to join as many people as possible here and to make something out of this.
Welcome!
It's not my project, but Carl's from the book.

I know you're right, but that's secondary now.
Read the post above, we have a much bigger problem right now!
Your post helped me discover what I wrote, thanks!

This is no longer valid.

[ivconic]

The least "painful" solution to this is to replace the charge-pump from the schematic with some DC-DC.
Of course; 7660 immediately comes to mind, "free-running" without external synchronization.
Apart from the voltage on the 7660 being limited to 10v... there is something else that makes me not like that solution, I can't see clearly what at the moment... but I feel it can be done better than that.


This is no longer valid.

[Carl-NC]

As I said before, I need a few days to thoroughly go through this. Apparently what happened is that I built a first PCB proto of the circuit (derived from the PI-GB circuit) and found some problems with it. I made corrections to the circuit but then forgot to transcribe those changes to the book schematic, and also never ordered a final PCB to double-check the design. It was an oversight, which I blame on the fact that the PI section was some of the earliest material I "completed" and just forgot about the state of this circuit.

Anyway, here is a partial list of the issues:

• The micro must be powered from VCC and GND, not GND and VEE.
• The sampling switches should be 74HCT4316, not 4066 (HC might work, I don't have any to test).
• If you use a 4053 for IC1, use the 74HCT variety.
• I need to add an input limiter to the 555 VCO.

I say partial because I'm not done yet. And, yes, Q1,Q2 can be any PMOS, I used the 9630 because it is common and cheap.


Edit: the 74HCT4053 has a max supply of 10V so it won't work at 12V. And the CD4053 (max 20V) needs a 70% VIH drive, or 8.4V @ 12V. So this will likely need an additional translator.

[ivconic]

Hey Carl, no one holds anything against you, don't get me wrong!
Writing a book of almost 700 pages is no joke, it is a very tiring and difficult job.
Even more, I know from previous (own) experiences; it's great that mistakes happen and mistakes exist!
Because this is the ideal way to completely "enter" the project and to understand the whole story better!
Mistakes "wake up" a person and motivate him to think more deeply.
A project without mistakes is not something that benefits learning.
I often make 40 mistakes in a text of 20 simple sentences!
In a book of 700 pages, a dozen benign mistakes is an unprecedented success!

[ivconic]

• The micro must be powered from VCC and GND, not GND and VEE. _______________________________________________cor rected in post #25
• The sampling switches should be 74HCT4316, not 4066 (HC might work, I don't have any to test).____________________________corrected in post #25
• If you use a 4053 for IC1, use the 74HCT variety.__________________________________________ ___________________ no comment
• I need to add an input limiter to the 555 VCO.______________________________________________ ________________waiting to be done

... And, yes, Q1,Q2 can be any PMOS, I used the 9630 because it is common and cheap.________________________________Detectorist#1's post #27 is probably the better choice

Edit: the 74HCT4053 has a max supply of 10V so it won't work at 12V. And the CD4053 (max 20V) needs a 70% VIH drive, or 8.4V @ 12V. So this will likely need an additional translator.

I just checked, the 74HCT4316 is easy to find and the price is good.

[Detectorist#1]

For controlling of CD4053, maybe the simplest way, as said Carl, transistor translator have to be used

[ivconic]

To my pleasant surprise, I found a whole series of drivers at a local store: TC426, TC427, TC428 and TC429.
The prices are quite affordable.
Now it's a matter of pure tradeoff arguments between a couple of discrete mosfets and this kind of driver.
4 discrete mosfets in a SOT-23 package take up less space on the pcb.
(SOT-23 is something I still manage to solder to the pcb)
But the driver chips should work better.

[Carl-NC]

I've just posted the schematic & PCB for the Bipolar PI design. I will post the source code as soon as I clean it up.

[Op04]

This is amazing breakthrough ...thank you so much Sir Carl

[algan]

Hello, Carl, I want to ask you, what exactly is this path colored white here for it probably cuts off the back side, but isn't it still connected? Thank you.

[Carl-NC]

It is a gap in the ground plane to isolate TX/digital ground noise from the RX.

[algan]

Thanks, Carl, can you tell me what program the file was made with? I want to import the Gerber file. I assume the program will be able to do it.

[Carl-NC]

I use Easy-PC. Here are the CAD files:

Pulse5_EasyPC.zip