Threshold Pot doesn't work

[h9361]

Thank you.
So, do you think we can remove Offset adjustment without any problem?

[GeoMax]

Thanks, so i will use 4066.
Dear Carl, as you know, i am re-designing HHD using Micro.
I want to remove R18 (offset) and R23 (trimmer). Do you have any suggestion for changing this to without trimmer?

[h9361]

JFETs won't work well in this case, where he wants to switch in a ground but the signal is bipolar.

Thanks, so i will use 4066.
Dear Carl, as you know, i am re-designing HHD using Micro.
I want to remove R18 (offset) and R23 (trimmer). Do you have any suggestion for changing this to without trimmer?

[Xtrem]

I would use one REED RELAY, nothing more efficient and simpler.No changes to the code or anything else.

[Carl-NC]

JFETs won't work well in this case, where he wants to switch in a ground but the signal is bipolar.

[GeoMax]

Hello h9361,

Instead of a third switch (CD4066), you could also use a FET switch like the J113. This would be easier to integrate into the circuit compared to an IC chip.

[h9361]

Probably you will need to add a third switch like this:


Also, why are you driving each pulse with 2 pins (S1 and S11, for example)?

Thanks.
A friend helped me.
I put code of target sample here.
S0_OFF_TIME is TX.
ALL_ON_TIME is sample width for all samples.
//------------Code-----------
TIM4->CCR1 = 36*200; // S1_1
TIM2->CCR2 = 36*400; // S1_2

TIM4->CCR1 = 36*(S1_OFF_TIME + S0_OFF_TIME ); // ON DELAY S1
TIM2->CCR2 = 36*(ALL_ON_TIME + S1_OFF_TIME + S0_OFF_TIME ); // S1 PW

[Carl-NC]

Probably you will need to add a third switch like this:


Also, why are you driving each pulse with 2 pins (S1 and S11, for example)?

[h9361]

Then you have to use the pins that support PWM.

Please forgive me, i can not understand.
Please see, it is my micro and voltage level of both sampling is +-5.
Can you tell me how can connect the EFE sampling to N4 (pin5 of 4066 switch) so that i can convert my HHD to single/double?

[Carl-NC]

Then you have to use the pins that support PWM.

[h9361]

Maybe you should measure the TX pulse width and frequency of the Lorenz. Often these large-coil detectors run a very wide pulse width at low frequency for detecting large deep targets.



That should work.



That should also work.



It depends on the micro and also how you intend to create the pulses. Are you going to bit-bang them or use PWMs? There are a lot of ways to do this.

Thank you for your supporting, dear Carl.
My method for micro is based on PWM.

[Carl-NC]

As you know, lorenz delay will be increased more than 70us if we fold frame to 150cm. But lorenz is detecting the shovel from higher depth with the higher delay, while i can not reach this depth with lower delay!

Do you have any suggestion for changing my hhd?

Maybe you should measure the TX pulse width and frequency of the Lorenz. Often these large-coil detectors run a very wide pulse width at low frequency for detecting large deep targets.

Do you think i can reach via following switch without removing R25 ( because i can not more edit on PCB)?

That should work.

One a method on pcb is, remove one pine of R27, c18 and R25. Then, connect them ( the opened pins) together in air.
See attached, do you have better solution?

That should also work.

But there is a big question. Please see your HHD schematic, i want to put both single and double sampling.
Can you guide me what output from micro (N4) can acts single sampling?
Other words, what output from micro can connect pin3 of IC8 to ground?

It depends on the micro and also how you intend to create the pulses. Are you going to bit-bang them or use PWMs? There are a lot of ways to do this.

[h9361]

Ideally high inductance gives you more "transformer gain" but practically there is not much difference.

Dear Carl
Please accept my apology for more questions.
I am going to make my HHD ( without GB, the your original schematic) with micro.
So, my micro will generate Frequency and two sampling pulses.
But there is a big question. Please see your HHD schematic, i want to put both single and double sampling.
Can you guide me what output from micro (N4) can acts single sampling?
Other words, what output from micro can connect pin3 of IC8 to ground?

[GeoMax]

Hi h9361

Thanks for the explanation. I didn't realize the depth difference was so significant with large coils and single sampling. Now I understand why guys from the Middle East and North Africa always rave about the PI Polones and say it "goes deep". The PI Polones is also a single-sample detector.

[h9361]

Hi H9361,

what is the benefit to choose between single and double sampling?

Hi dear GeoMax

The single sampling is a simple pi.
This is not good for using coil, it is good only for using big frame.
At least, 150 x 150 cm or bigger.
Since the frame is big, so it will not detect any small objects or it has very low sensitivity to minerization. So it is a bit stable and does not need EFE sampling.
But its benefit is reaching to a very very high depth for bigger object.
I want to add this mode to my HHD for using on special point.
For exp, i tested lorenz z2, it has two modes: 1- single sampling 2- two sampling
In two sampling, it exactly detect objects like HHD depth.
But its single sampling mode detects very higher depth.
For exp, i tested iron shovel with the two modes:
Single sampling: 370cm depth
Two sampling : 200-230 cm
I think we can use this mode in some ground.