Superscan PI

[ZOUjiarui]

hell The damping resistor is 150Ω, and I'm not very familiar with using oscilloscopes yet. I can't zero the 061 and 072, and the 740 keeps getting hot, but it hasn't burned out.

[nasios]

hell The damping resistor is 150Ω, and I'm not very familiar with using oscilloscopes yet. I can't zero the 061 and 072, and the 740 keeps getting hot, but it hasn't burned out.

is normal to be hot is 24v, now i look your youtbe video and i look you use to many wire cable, maybe make capacitance
look this video for help you with R
https://www.youtube.com/watch?v=Gr__N4_k2Mc&t=3s

[ZOUjiarui]

Hello, I retested the coil waveform, and it's not a square wave; it's not normal.

[eduardo1979]

It's very likely that the MOSFET overheating is due to the 24V voltage, as our colleague NASIOS stated. I built the Superscan, but I never powered it with 24V. My Superscan was powered by 12V, and I remember that the MOSFET didn't get hot at all; it was just lukewarm. I used an IRF840, as it has a higher breakdown voltage than the IRF740. I recall that the depth of my Superscan was quite good; it detected a 33mL can of Coca-Cola at a depth of 1.5m with a 1m x 1m frame coil. I did this test in a moderately mineralized soil section. The coil had two turns of Category 5 UTP cable, which is a total of 16 turns, since the cable has 8 wires. I don't remember the value of the damping resistor, but it's quite important, as it can greatly influence the detector's depth. I used an NE5534 in the preamplifier. It's also important that the op-amp be original. I'll repeat that this detector isn't suitable for searching in highly mineralized clay soils, like red clay. For that, you need a detector with ground balance. I abandoned this project many years ago for this very reason. If you want a good detector that's suitable for all types of terrain, you can opt for the GS-5 Lite with the same timings and operating frequency as the Superscan. Don't waste your time and money on things that have already been tried and tested and didn't produce good results.

[ZOUjiarui]

Hello eduardo1979, I would be very happy to build a ground-balanced metal detector, like the SD2000, or a genuine GS6, using an 80cm diameter detection coil. I'm not sure if the GS5Lite is suitable for large coils.

[eduardo1979]

Hello eduardo1979, I would be very happy to build a ground-balanced metal detector, like the SD2000, or a genuine GS6, using an 80cm diameter detection coil. I'm not sure if the GS5Lite is suitable for large coils.

The GS-5 LITE requires some modifications to function properly with 80cm x 80cm or 1m x 1m frame-style coils. This detector operates at a very high frequency and is designed for small, low-conductivity objects. The frequency would need to be lowered, the first main sample delay increased to over 40µs, and the synchronization times adjusted, similar to the GS-6 or Superscan.

[ZOUjiarui]

I have to get to the task at hand: superscan, readjusting another detector, which is still quite difficult for me.

[ZOUjiarui]

我重新测试了线圈波形：1. 空载条件下。2. 阻尼电阻从 150Ω 增加到 300Ω。（图 3 显示的是 150Ω 时的波形，未做任何修改。）我怀疑问题出在线圈上，但更换阻尼电阻后，波形中出现了一条额外的直线。

[ZOUjiarui]

The frequency and pulse width displayed on the oscilloscope waveform may be incorrect when manually adjusted; they only display correctly when automatically adjusted.

[ZOUjiarui]

I retested the coil waveform: 1. Under no-load conditions. 2. The damping resistor was increased from 150Ω to 300Ω. (Figure 3 shows the waveform at 150Ω without any modifications.) I suspected the problem was with the coil, but after changing the damping resistor, an extra straight line appeared in the waveform.