LOOKING FOR GOLDSCAN 4 Schematic.

[tuntunlin]

Hello tuntunlin , sorry for the delay in replying; I’ve been very busy with work. I haven't tested the detector in the field yet—only on the bench. Since I built this unit specifically for use with the 11" Mono Commander coil, I reduced the pulse to 80µs and the frequency to 2650Hz, and I used a high-wattage damping resistor because the coil has low resistance (0.9 ohms).

Greetings, Emerson Paz. Thank you for your reply.
Based on my current tests, after your detector rejects hot rocks, does it still have good depth performance? In that condition, does the detector produce any chatter or vibrating noise?

I would also like to know: are you using the original LT1114 IC as specified, or have you used any substitute? Please let me know.

Thank you.

[Emersonpaz]

Greetings, Emerson Paz.
I would like to ask you with respect.

After you have fully built your GS5 Lite, could you please share your data and results as well?

I would like to know: does your unit work well across the delay range from 10µs to 25µs, or does it only work at a specific fixed delay setting? Also, does the ground balance function properly throughout the 10µs to 25µs delay range?

I would also like to know what frequency and pulse width settings you are currently using.

Additionally, after the ground balance rejects hot rocks, have you observed any improvements in target discrimination and sensitivity?

Please kindly reply. Thank you.

Hello tuntunlin , sorry for the delay in replying; I’ve been very busy with work. I haven't tested the detector in the field yet—only on the bench. Since I built this unit specifically for use with the 11" Mono Commander coil, I reduced the pulse to 80µs and the frequency to 2650Hz, and I used a high-wattage damping resistor because the coil has low resistance (0.9 ohms).

[GeoMax]

Since I cannot upload images on the forum, I will upload a video on YouTube and show it there.

If you're having trouble uploading images, they're probably too large. I always have to reduce the image resolution to be able to upload images; otherwise, it doesn't work either.

[tuntunlin]

Since I cannot upload images on the forum, I will upload a video on YouTube and show it there.

[tuntunlin]

To modify the pulse width, you need to change the value of resistor R13, which is currently 6.8kΩ. You should replace it with a 10kΩ potentiometer in series with a 2.2kΩ fixed resistor. With the potentiometer, you could adjust the pulse width below and above 100µs. The wire I used to use for my coils was 24AWG stranded wire with PVC insulation. Now I use Litz wire for all my coils. You should use graphite paint instead of aluminum foil for shielding your coils. The coaxial cable is also very important, as its capacitance can significantly affect the detection of low-conductivity targets. If you lower the pulse width to 80µs, you could increase the frequency to 3kHz. What you're experiencing with the coils, I believe, is due to their high capacitance, or the high capacitance of the coaxial cable. I'd like to see an oscilloscope image showing the measurement at pin 6 of the NE5534. That way we can see the waveform and draw some conclusions.

Thank you very much for the complete and thorough answer, Eduardo.
I will now show you the waveform at pin 6 of the NE5534.

[eduardo1979]

Thank you, Eduardo. I appreciate your explanation.
Based on my current tests, I have found the best results with the damping resistor at 680Ω when using an oscilloscope. I tested both a small coil and a large coil (both 300µH). The small coil works best at a 15µs delay, while the large coil works best at a 22µs delay.

My question is: what could be the possible issues preventing a single coil from working across all delay ranges?

The 470Ω damping resistor I mentioned in my previous post was a value I adjusted while using aluminum tape wrapped around the 300µH coil. Now I am using 25 SWG coil wire wound to 300µH. The fact that it only works at a fixed delay rather than across all delays—could this be due to the wire gauge size?

The current DC resistance of my coil is approximately 1.6Ω.

Therefore, I would also like to know what wire gauge size you (the teachers/mentors) are using for your coils.

My step-by-step adjustments so far are as follows:

· Damping resistor: set to 680Ω (optimized with oscilloscope)
· Frequency: set to 2.8 kHz
· NE5534 offset: adjusted to 0V DC
· Supply voltage: 14.5V

I am looking forward to your answers. Thank you all very much.

To modify the pulse width, you need to change the value of resistor R13, which is currently 6.8kΩ. You should replace it with a 10kΩ potentiometer in series with a 2.2kΩ fixed resistor. With the potentiometer, you could adjust the pulse width below and above 100µs. The wire I used to use for my coils was 24AWG stranded wire with PVC insulation. Now I use Litz wire for all my coils. You should use graphite paint instead of aluminum foil for shielding your coils. The coaxial cable is also very important, as its capacitance can significantly affect the detection of low-conductivity targets. If you lower the pulse width to 80µs, you could increase the frequency to 3kHz. What you're experiencing with the coils, I believe, is due to their high capacitance, or the high capacitance of the coaxial cable. I'd like to see an oscilloscope image showing the measurement at pin 6 of the NE5534. That way we can see the waveform and draw some conclusions.

[tuntunlin]

Eduardo,
I would like to know which component(s) need to be changed in order to adjust the pulse width from 100µs down to 80µs.

[tuntunlin]

Hello. The detector works correctly with any delay level, but if you change the delay, for example from 10µs to 15µs, you always have to readjust the ground balance. The delay is a feature of the detector that helps eliminate certain low-conductivity non-ferrous metals, such as aluminum foil, etc. If you want to search for gold nuggets, I recommend setting the delay to 10µs and properly adjusting the ground balance. If your intention is to search for jewelry on the beach, you should use a slightly higher delay, such as 15µs, since the effect of salinity could affect the detector, causing it to emit false signals continuously. Also, on white sand beaches without mineralization, you could detect with the ground balance at the minimum level, thus gaining a little more depth for small gold targets. The frequency I used was approximately 2.8 kHz, and the TX pulse width was 100µs. Obviously, with a pulse width of 100µs, the IRF740 heats up more and power consumption increases. I recommend a pulse width of 80µs to avoid all these problems. A very high pulse width is useless if your coil saturates. To answer your last question, I'd like to know if there are any hot rocks in your search area. If there are, you'll have to avoid them to search for other targets, but by increasing the ground balance level, you'll notice a slight loss of depth. Keep in mind that this detector doesn't discriminate between ferrous and non-ferrous metals; instead, it discriminates based on conductivity (high and low). If you want to learn how this detector actually works, search online for the instruction manual for the Whites TDI SL detector; that will greatly help you understand the true operation of the GS-5.

Thank you, Eduardo. I appreciate your explanation.
Based on my current tests, I have found the best results with the damping resistor at 680Ω when using an oscilloscope. I tested both a small coil and a large coil (both 300µH). The small coil works best at a 15µs delay, while the large coil works best at a 22µs delay.

My question is: what could be the possible issues preventing a single coil from working across all delay ranges?

The 470Ω damping resistor I mentioned in my previous post was a value I adjusted while using aluminum tape wrapped around the 300µH coil. Now I am using 25 SWG coil wire wound to 300µH. The fact that it only works at a fixed delay rather than across all delays—could this be due to the wire gauge size?

The current DC resistance of my coil is approximately 1.6Ω.

Therefore, I would also like to know what wire gauge size you (the teachers/mentors) are using for your coils.

My step-by-step adjustments so far are as follows:

· Damping resistor: set to 680Ω (optimized with oscilloscope)
· Frequency: set to 2.8 kHz
· NE5534 offset: adjusted to 0V DC
· Supply voltage: 14.5V

I am looking forward to your answers. Thank you all very much.

[eduardo1979]

Greetings to all the brothers who have successfully built the GS5 Lite.
I would like to ask you with respect.

On the GS5 Lite, does it work well across the delay range from 10µs to 25µs, or does it only work at a specific fixed delay setting? I would like to know.

Does the ground balance function properly throughout the 10µs to 25µs delay range?

I would also like to know what frequency and pulse width settings you are currently using.

Additionally, after the ground balance rejects hot rocks, have you observed any improvements in target discrimination and sensitivity?

Please kindly reply. Thank you.

Hello. The detector works correctly with any delay level, but if you change the delay, for example from 10µs to 15µs, you always have to readjust the ground balance. The delay is a feature of the detector that helps eliminate certain low-conductivity non-ferrous metals, such as aluminum foil, etc. If you want to search for gold nuggets, I recommend setting the delay to 10µs and properly adjusting the ground balance. If your intention is to search for jewelry on the beach, you should use a slightly higher delay, such as 15µs, since the effect of salinity could affect the detector, causing it to emit false signals continuously. Also, on white sand beaches without mineralization, you could detect with the ground balance at the minimum level, thus gaining a little more depth for small gold targets. The frequency I used was approximately 2.8 kHz, and the TX pulse width was 100µs. Obviously, with a pulse width of 100µs, the IRF740 heats up more and power consumption increases. I recommend a pulse width of 80µs to avoid all these problems. A very high pulse width is useless if your coil saturates. To answer your last question, I'd like to know if there are any hot rocks in your search area. If there are, you'll have to avoid them to search for other targets, but by increasing the ground balance level, you'll notice a slight loss of depth. Keep in mind that this detector doesn't discriminate between ferrous and non-ferrous metals; instead, it discriminates based on conductivity (high and low). If you want to learn how this detector actually works, search online for the instruction manual for the Whites TDI SL detector; that will greatly help you understand the true operation of the GS-5.

[tuntunlin]

Greetings to all the brothers who have successfully built the GS5 Lite.
I would like to ask you with respect.

On the GS5 Lite, does it work well across the delay range from 10µs to 25µs, or does it only work at a specific fixed delay setting? I would like to know.

Does the ground balance function properly throughout the 10µs to 25µs delay range?

I would also like to know what frequency and pulse width settings you are currently using.

Additionally, after the ground balance rejects hot rocks, have you observed any improvements in target discrimination and sensitivity?

Please kindly reply. Thank you.

[tuntunlin]

If you have a clear photo of your board with the ICs mounted and everything looks correct, it seems like you might be using a counterfeit IC.

Greetings, Emerson Paz.
I would like to ask you with respect.

After you have fully built your GS5 Lite, could you please share your data and results as well?

I would like to know: does your unit work well across the delay range from 10µs to 25µs, or does it only work at a specific fixed delay setting? Also, does the ground balance function properly throughout the 10µs to 25µs delay range?

I would also like to know what frequency and pulse width settings you are currently using.

Additionally, after the ground balance rejects hot rocks, have you observed any improvements in target discrimination and sensitivity?

Please kindly reply. Thank you.

[tuntunlin]

Hi. I've been working on this circuit for about ten days, and I exactly built Eduardo's schematic. But when I set the frequency knob to 1k, the 7912 regulator gets overly hot. When I change the knob to 25k and use a frequency of 1300Hz, the regulator voltage fluctuates by 5 volts. The VR3 potentiometer really doesn’t do much. The loop resistance is 2 ohms and its inductance is 440 microhenries. If I use a 25k knob instead of 1k, the heating problem is solved, and it can detect a 3 cm coin at 30 cm. But the GEB is off and it also detects broken ceramics. When I turn on the GEB, the board’s sensitivity drops drastically. Overall, this circuit wasn’t what I expected and it can’t really work in the field.

Greetings.
Because I am not satisfied with the current op-amp I am using, I have ordered an authentic/genuine NE5534. Once it arrives, I will test and verify it, and then share the results and data. I am also still in the process of testing. Thank you to all the teachers and mentors on the forum.

[David222]

Hi David!

These are José's PCB files. [ATTACH]n450564[/ATTACH] [ATTACH]n450565[/ATTACH]

Hi. I have seen these. And Jose said that this circuit needs some changes, but the changes are stated in a scattered manner. I have read this thread more than 4 times. I apologize for the bad English. Thanks for the file and the effort you put in. I thank all the friends present in this forum for their efforts.

[Ruben2000]

Thanks. Yes, it's different. I have seen José's circuit films. His GS4 works much better than the GS5. But unfortunately, its PCB file is not in the forum. Or maybe I can't find it. I have read these 48 pages three times, but I didn't find anything.

Hi David!

These are José's PCB files. GoldScan 4 Yerleşim Planı (1).pdf GoldScan 4 PCB (4).pdf

[David222]

7912 regulator pinout is NOT as 7812. look in google.

Thanks. Yes, it's different. I have seen José's circuit films. His GS4 works much better than the GS5. But unfortunately, its PCB file is not in the forum. Or maybe I can't find it. I have read these 48 pages three times, but I didn't find anything.