Threshold Pot doesn't work

[Carl-NC]

Connect to the other side of R24, and increase the 2.2k to 10k.

[GeoMax]

Hello
Dear Carl
I hope you are passing good days.
As you know, i am using the audio schematic (#339 post in this thread) for my HHD.
In addition, i added a DISC schematic for Fe detection (you can see its end part, output) and it works but its output is uV.


Now, i want to connect my DISC output to the audio schematic so that my audio generates a silent or cut off sound if the DISC pcb have an output.
Is is possible to guide me which points are better to be connected together?
Thank you.

From which schematic is this circuit part?

[h9361]

Connect to the other side of R24, and increase the 2.2k to 10k.

Thank you dear Carl for your kindness.

[GeoMax]

Hi H9361,

from which detector schematic have you taken the "DISC output" circuit part below?

[h9361]

Connect to the other side of R24, and increase the 2.2k to 10k.

Dear Carl
I have a question about HHD.
I have heard that some people has increased voltage of search coil.
Other words, they transmits higher voltage levels from search coil.
Is it possible to give me a brief explanation about this?
I want to test this on my HHD. Can you tell me which point of HHD i can play for different voltage levels?
Thank you.

[GeoMax]

To what voltage level do you want to increase the search coil voltage? If you use the ICL7660 in your circuit you do not have much "room" to increase the voltage level. If you using a LT1054 you can go upto 15 volt input voltage. Just increase your battery voltage. If you need more voltage like 24V or more you need to modify the HHD circuit accordingly.

Others...
Can you reply to my question #394 above?

[h9361]

Hi H9361,

from which detector schematic have you taken the "DISC output" circuit part below?

Read Voodoo thread, it is inside it.

[h9361]

To what voltage level do you want to increase the search coil voltage? If you use the ICL7660 in your circuit you do not have much "room" to increase the voltage level. If you using a LT1054 you can go upto 15 volt input voltage. Just increase your battery voltage. If you need more voltage like 24V or more you need to modify the HHD circuit accordingly.

Others...
Can you reply to my question #394 above?

Thank you.
My mean is increasing voltage of transmitted signal into coil.
For exp, Minelab is also using this method (DVT) .

[GeoMax]

Hi h9361,

yes, you can increase the battery voltage to 15V if your circuit uses a genuine LT1054 IC chip within the power supply. If your LT1054 chip "burns" at 15V it is probably one of these Chinese fake IC chips (7660 re-labeld to 1054). If your circuit has a ICL7660 chip, you actually can not increase the battery voltage. Based on the Datasheet the ICL7660 chip can handle 10,5V battery input voltage only. In regards to the (HHD) power supply circuit, check out also the schematic for details. The search coil with the MosFet and the 1 Ohm resistor in series is directly connected between battery minus (-VB) and battery plus (VB) poles.

[h9361]

Hi h9361,

yes, you can increase the battery voltage to 15V if your circuit uses a genuine LT1054 IC chip within the power supply. If your LT1054 chip "burns" at 15V it is probably one of these Chinese fake IC chips (7660 re-labeld to 1054). If your circuit has a ICL7660 chip, you actually can not increase the battery voltage. Based on the Datasheet the ICL7660 chip can handle 10,5V battery input voltage only. In regards to the (HHD) power supply circuit, check out also the schematic for details. The search coil with the MosFet and the 1 Ohm resistor in series is directly connected between battery minus (-VB) and battery plus (VB) poles.

Thank you for your tip.

[h9361]

Connect to the other side of R24, and increase the 2.2k to 10k.

Dear Carl
I tried different RX inductance (DD) with different resistor for finding best damping resistor+inductance.
Unfortunately, i could not find the best values.
Have you already measured this for HHD?

[h9361]

Dear Carl
Finally, i could find the best values.
Thank you.

[h9361]

Hi h9361,

yes, you can increase the battery voltage to 15V if your circuit uses a genuine LT1054 IC chip within the power supply. If your LT1054 chip "burns" at 15V it is probably one of these Chinese fake IC chips (7660 re-labeld to 1054). If your circuit has a ICL7660 chip, you actually can not increase the battery voltage. Based on the Datasheet the ICL7660 chip can handle 10,5V battery input voltage only. In regards to the (HHD) power supply circuit, check out also the schematic for details. The search coil with the MosFet and the 1 Ohm resistor in series is directly connected between battery minus (-VB) and battery plus (VB) poles.

Dear Sir,
If i increase supply voltage to 15V, do you think i should increase also 1 ohm resistor?

[h9361]

Connect to the other side of R24, and increase the 2.2k to 10k.

Dear Carl
Please read the attached picture, it belongs to Minelab method ( it used for increasing sensitivity to small targets).
Do you think i can increase sensitivity of my HHD to small object via increasing voltage supply to 15V ( off course, by changing 7660 to 7662 or LT1054) ?

[Carl-NC]

Minelab's DVT uses short high-voltage pulses combined with long low-voltage pulses to implement an improved ground balance. You can increase sensitivity by just increasing the TX voltage but power (heat) will also increase. You can also increase sensitivity by increasing either the TX pulse width or the TX pulse frequency, but again power (heat) will also increase. If you just want to find small targets (small gold nuggets) then you can decrease the pulse width and increase the frequency to improve sensitivity. I would try this before increasing the TX voltage. If you want excellent sensitivity to both small and large targets then you probably need a multi-pulse design.