Bipolar PI design

[algan]

Hello colleagues, hello Carl. I built my bipolar detector, but it differs from yours; the input stage is the same, except I’m using an NE5534 IC. The output at pin 6 is fine, but with a 28cm coil, I get no response to a coin—though I do get a response to larger objects. Is it worth changing the 100k resistors, and is there an alternative input configuration possible after the two input pulses? Thanks.

[Carl-NC]

I am re-designing your schematic, do you think i can replace a tl074 for Ic5 and Ic4?

Can i replace tl064 with tl074?

Yes and yes.

[h9361]

Hello.
Yes, GND and -5V.

Dear sir,
About your Audio,
Can i replace tl064 with tl074?
thanks

[h9361]

Yes

Dear carl,
I am re-designing your schematic, do you think i can replace a tl074 for Ic5 and Ic4?

[Carl-NC]

Yes

[h9361]

This is where pot values get converted into timing values:

Bool ADC_Run(void)
{
if(ADC_GetPot1() || ADC_GetPot2()) // If either pot has changed value
{
Settings.TgtDelay = ( 50 + Pot1Value) << 1; // Min = 50 (12.5us), max = 113 (28.25us)
Settings.TxWidth = ( 50 + Pot2Value) << 3; // Min = 50us, max = 305us
Settings.TxPeriod = (200 + (Pot2Value << 2)) << 3; // Min = 200us, max = 1220us
return True;
}
return False;
}​

The problem is, a minimum TxPeriod of 50us (20kHz) requires reducing everything else to fit. You would first need to drop the TxWidth down to, say, 10-15us and go from there.

Hello
Dear Carl
Can you tell me GB delay in code? Is it 5us?

[Carl-NC]

Try this:

[algan]

Hi Carl I want to try the TDI ground balance, but on your bipolar circuit. Can you tell me how I should connect them correctly? Thanks.

[Carl-NC]

This is discussed in ITMD3 and in various threads on these forums. In a nutshell:

Single MOSFET: fastest, simplest, single-ended pulses, requires EFE samples
Half-bridge: slower, less simple, bipolar pulsing, no EFE samples, less balanced
Full bridge: slowest, least simple, bipolar pulsing, no EFE samples, fully balanced

[Haydar]

Can someone provide a detailed explanation of the circuit effects, efficiency differences, and the pros and cons of using single MOSFET, half-bridge, and full-bridge topologies for driving coils in pulse induction systems?

[Carl-NC]

I think, the aim of Carl with ITMDx is not to gives ready receipts for repeating. The schemes in the these books are more as educational platforms for the readers.

Where a complete schematic is presented in ITMD3, it should be a completely working schematic (except for known errata). You are right, the circuits are primarily for teaching and therefore may be simplified and not be as high-performance as they could be. But they are good starting points.

[Detectorist#1]

Hi pechkata,
Yes, I agree with you, sometimes the grapes are sour for some people...

[pechkata]

Hi pechkata,
I never assembled this project from ITMD3 book. I think, the aim of Carl with ITMDx is not to gives ready receipts for repeating. The schemes in the these books are more as educational platforms for the readers.
For those who only repeats the schemes from the book, it will be more faster and cheaper to buy one ready MD for some manufacturer with good reputation.

Hello Detectorist#1
It has nothing to do with what you wrote.
The schematics are completely identical to what we need.
It just takes a little logic to put the system together.
Carl-NC gives you an idea - not a detector.
And don't dwell on the sour grapes.

[pechkata]

I was testing this part

Hi Pito - this has nothing to do with the project in this topic.

[Detectorist#1]

Hi pechkata,
I never assembled this project from ITMD3 book. I think, the aim of Carl with ITMDx is not to gives ready receipts for repeating. The schemes in the these books are more as educational platforms for the readers.
For those who only repeats the schemes from the book, it will be more faster and cheaper to buy one ready MD for some manufacturer with good reputation.