Threshold Pot doesn't work

[h9361]

No, it still won't work for a mono coil. You can't apply 12v to an opamp that is running on +/-5V.

I still don't understand why you want to run the micro from -5V. If you run it from +5V you can rid of all the level translators.

Do you have any idea or solution for mono/dd coil?
My ground is -vb.
About micro, it designed by my friend, i will ask him.

[Carl-NC]

Do you have any idea or solution for mono/dd coil?

1. Make +VB = ground
2. Capacitor-couple the TX signal to the preamp (as in ITMD2)
3. Use a PMOS driver
4. Use a floating bipolar driver

[h9361]

1. Make +VB = ground
2. Capacitor-couple the TX signal to the preamp (as in ITMD2)
3. Use a PMOS driver
4. Use a floating bipolar driver

So, i have to use this power like HHD.

And my TX part is as follow

Is this true for DD and mono?

[Carl-NC]

Yes, and yes.

[h9361]

Yes, and yes.

Thank you.
In this case, can i use j6 as switching mono/DD?

[Carl-NC]

Yes

[h9361]

Yes

please forgive me for more questions.
Thank you.

[h9361]

Yes

Dear Carl
I remember that you posted the picture about Iron DISC when TX is on:

And please consider the following schematic for detecting Iron via increasing voltage:

First Question, Which points do you prefer to be connected to R27 and R8 (two diodes, DD Coil) to PI schematic in #Post 498?

Second question, which of the following sampling (when TX is ON) is better (whole TX pulse or first part)?


I simulated the DISC schematic on software and played with BW capacitors (C13 and C15).
I make a simple Pulse generator with 100us and connected it to the differential integrated as input (following picture).

Then i connected its output to Scope.
Other question, which of the triangular waveforms do you think it is better for detecting increasing voltage?

[Carl-NC]

It looks like you are trying to add a VLF-disc circuit to a PI. All you need to do is add another demodulator to the existing PI and sample the TX-on signal from the preamp. Keep in mind this will only work for an IB coil (like DD), not a mono coil. You can try different sample points to see what works the best.

[h9361]

It looks like you are trying to add a VLF-disc circuit to a PI. All you need to do is add another demodulator to the existing PI and sample the TX-on signal from the preamp. Keep in mind this will only work for an IB coil (like DD), not a mono coil. You can try different sample points to see what works the best.

Thank you for your guide.
Please forgive me for my primary questions.
You advised me to use a demodulator to existing PI and sample TX-ON.
Please see attached, i adjusts my S1 pulse (produced by 74hc221) exactly on TX on signal from preamp (5534 output) via 4066.
After that, there are two stages differential (TL072). Does the two stages act demodulator action that you mentioned?
I saw your Raptor schematic and its explanation, you also used such structure for that.
Thank you.

[Carl-NC]

Add another demodulator stage, like this:

It needs to reasonably match the other demods in terms of signal delay. You will then need to figure out what to do with the new signal. One possibility is to use it to alter the frequency of the audio output so you get a very low grunt tone when iron is detected. I don't know what the rest of your circuit looks like so I cannot help with this.

[h9361]

Add another demodulator stage, like this:

It needs to reasonably match the other demods in terms of signal delay. You will then need to figure out what to do with the new signal. One possibility is to use it to alter the frequency of the audio output so you get a very low grunt tone when iron is detected. I don't know what the rest of your circuit looks like so I cannot help with this.

Thank you very very much for your information.
I want to cut off audio ( silence ) if my DISC part detects any Iron (increasing voltage for TX on).
My audio out is like the following (like Mr. Detectorist ):
Is it possible to connect to audio so that its audio goes to silence like GPX?

[Carl-NC]

Probably something like this will work:

You will need to figure out what goes inside the box, it may be as simple as a single amplifier stage.

[h9361]

Probably something like this will work:

You will need to figure out what goes inside the box, it may be as simple as a single amplifier stage.

Thank you.
Do you think the following can work with Iron rejection Pot?
And only i have an Iron rejection if first my detector detects a Metal.

[Carl-NC]

That circuit is used in VLF detectors, the signals are different in a PI detector. You will need to add the demodulator and then find out how that signal behaves with ferrous targets, non-ferrous targets, and ground. This includes changing the demod timing to see how that changes the signals. You should be able to find something that works well enough on at least some targets. Then compare the iron signal to the GB signal and figure out how to combine them to blank the audio. They are both motion-mode signals so you may not even need to combine them, I don't know.