Metal detector for medium-large objects

[eduardo1979]

Hi Eduardo1979,

What is actually the operating pps of the GS5, GS5lite and GS6?

Hi Geomax. The GS5 Lite's frequency is adjustable from 2.6 to 3 kHz. I set mine to 2.8 kHz and the TX pulse width to 100 µs.

I assume the GS5 has the same frequency, or very similar. The GS6 has the same frequency as the Surf Master Pi, around 615 Hz.

[GeoMax]

Hi Eduardo1979,

thanks for the reply.

[David222]

Hello friends. I have a strange problem. I made the GS5 Eduardo and chose its coil of 2 ohms and 412 uH. I chose a frequency between 1300 and 1500 Hz. Because more than this the 7912 regulator heats up. In this range its performance is better than all pi devices. I used 20 meters of enameled wire with a diameter of 0.5mm on a 30 cm core. With these specifications, it detects a coin with a diameter of 2.5 cm in the air at 35 cm. So far, no problem. But I made a coil with the same specifications of 2 ohms and 412 uH; but this time I increased its diameter to 40 cm. But this time, surprisingly, it did not detect the coin at a greater depth. I even increased the dimensions of the metal and used a large can of Lotfett brand soldering oil, which is 6.5 cm in diameter; but it still detected it at 55 cm, like a 30 cm loop. The depth should have increased as the loop got bigger, but this didn't happen. I don't understand why.

I'm planning to use a larger loop for more depth for the GS5 Eduardo. But I don't know if that's possible. But the sound of the GS5 Eduardo is unique. I love the beautiful sound it makes when it reveals the metal. The sound is smooth and high quality and very beautiful.

[gurdal]

Hello David222
This might be a classic question, but...
Does the GS5 discrimination work well?
Best regards,

Gurdal

[eduardo1979]

Hello friends. I have a strange problem. I made the GS5 Eduardo and chose its coil of 2 ohms and 412 uH. I chose a frequency between 1300 and 1500 Hz. Because more than this the 7912 regulator heats up. In this range its performance is better than all pi devices. I used 20 meters of enameled wire with a diameter of 0.5mm on a 30 cm core. With these specifications, it detects a coin with a diameter of 2.5 cm in the air at 35 cm. So far, no problem. But I made a coil with the same specifications of 2 ohms and 412 uH; but this time I increased its diameter to 40 cm. But this time, surprisingly, it did not detect the coin at a greater depth. I even increased the dimensions of the metal and used a large can of Lotfett brand soldering oil, which is 6.5 cm in diameter; but it still detected it at 55 cm, like a 30 cm loop. The depth should have increased as the loop got bigger, but this didn't happen. I don't understand why.

I'm planning to use a larger loop for more depth for the GS5 Eduardo. But I don't know if that's possible. But the sound of the GS5 Eduardo is unique. I love the beautiful sound it makes when it reveals the metal. The sound is smooth and high quality and very beautiful.

Hi David. With the new 40cm diameter coil, you'll probably need to change the damping resistor value, as this can sometimes happen. The NE5534 offset setting, the coaxial cable you're using, and the main sample delay setting can also influence the results. There are many factors to consider. Theoretically, with a larger coil, you should detect larger objects at greater depths than with a smaller diameter coil. The coaxial cable's capacitance is very important, as is the coil's. Try making a coil with Category 5 UTP cable (the kind used for internet networks), as it typically has lower capacitance than standard enameled copper cable. You should also try replacing R7 (2.2kΩ) with a 1kΩ resistor. This would give you a bit more depth and reduce thermal noise, but it might overload the preamplifier. If that happens, you should replace the 1M resistor R8 with a 470K resistor. This will maintain virtually the same gain, but reduce thermal noise and increase the preamp's speed.

[David222]

Hi David. With the new 40cm diameter coil, you'll probably need to change the damping resistor value, as this can sometimes happen. The NE5534 offset setting, the coaxial cable you're using, and the main sample delay setting can also influence the results. There are many factors to consider. Theoretically, with a larger coil, you should detect larger objects at greater depths than with a smaller diameter coil. The coaxial cable's capacitance is very important, as is the coil's. Try making a coil with Category 5 UTP cable (the kind used for internet networks), as it typically has lower capacitance than standard enameled copper cable. You should also try replacing R7 (2.2kΩ) with a 1kΩ resistor. This would give you a bit more depth and reduce thermal noise, but it might overload the preamplifier. If that happens, you should replace the 1M resistor R8 with a 470K resistor. This will maintain virtually the same gain, but reduce thermal noise and increase the preamp's speed.

Eduardo, I thank you. I will do this test as soon as possible.

[David222]

Hello David222
This might be a classic question, but...
Does the GS5 discrimination work well?
Best regards,

Gurdal

Hello. Yes, its differentiation works by changing the tone of voice.

[David222]

Hi David. With the new 40cm diameter coil, you'll probably need to change the damping resistor value, as this can sometimes happen. The NE5534 offset setting, the coaxial cable you're using, and the main sample delay setting can also influence the results. There are many factors to consider. Theoretically, with a larger coil, you should detect larger objects at greater depths than with a smaller diameter coil. The coaxial cable's capacitance is very important, as is the coil's. Try making a coil with Category 5 UTP cable (the kind used for internet networks), as it typically has lower capacitance than standard enameled copper cable. You should also try replacing R7 (2.2kΩ) with a 1kΩ resistor. This would give you a bit more depth and reduce thermal noise, but it might overload the preamplifier. If that happens, you should replace the 1M resistor R8 with a 470K resistor. This will maintain virtually the same gain, but reduce thermal noise and increase the preamp's speed.

Hi Eduardo. I followed your instructions and instead of the 2.2k resistor, I used two 2.2k resistors in parallel, which have good power and a value of 1.1k. You were right, it detects two cents more and the 7912 regulator runs cooler. I left the device on for 5 hours continuously and set the battery warning trimmer to 14.5 volts. As a result, the circuit was able to run for 5 hours continuously with 4 18650 and 2200 mAh batteries. After that, the battery warning light came on. And it took two hours for the batteries to fully recharge. Thank you. Do you know of another circuit that has the same quality but detects more depth?

[algan]

There are many versions of the GS-6 flying around the internet, but this is the correct one.

Hello, eduardo1979, do you have a video clip of how GS-6 works? Thank you.
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[eduardo1979]

Hello, eduardo1979, do you have a video clip of how GS-6 works? Thank you.
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Hi Algan.
I don't have any videos of the GS-6, but I found one on YouTube. Here's the link.
https://www.youtube.com/watch?v=RNjrlXEo_D0