Superscan PI

[nasios]

Hello. This is abnormal; it heats up rapidly, becoming scalding to the touch within 1-2 minutes.

maybe is too fast the hz and work fast the mosfet you have to use oscilloscope
you can share the pcb for i try?

[ZOUjiarui]

maybe is too fast the hz and work fast the mosfet you have to use oscilloscope
you can share the pcb for i try?

Hello, the handheld oscilloscope is on its way, and I will remeasure it. There are no secrets to the circuit board; just solder the components according to the hand-drawn circuit diagram.

[ZOUjiarui]

The PCB itself is fine; the problem lies with the characters. My test results are still not quite right, and I need someone with experience to give us some pointers.

[ZOUjiarui]

The 555 timer frequency is correct, but the frequency of the 1k resistor at pin 3 is fluctuating wildly, while the coil frequency is correct. The MOSFET is still generating heat, and the coil is still making noise. Please help me, thank you very much.

[ZOUjiarui]

The waveform at position 1kHz is the same 90Hz, which was my mistake. Figure 2 is correct; the pulse width is 0.47ms, and the waveform is clearly not a square wave.

[ZOUjiarui]

correct

[nasios]

correct

in my eye all is correct, the heat maybe is in normal degree (i finish before few days the felejoo pi and have heat and when i use aluminium for cooling is ok) the coil i don't understand why make noise , you can shere a photo of coil? maybe is very open the loop?

[ZOUjiarui]

Yes, it's operating at high power. The coil might be unsuitable; it's wrapped in paper. The diameter is 10 cm, the resistance is 1 ohm, and the wire diameter is 0.6 mm. After adjusting the frequency, it's indeed much more normal; a 2W high resistance can be detected at around 5 cm. I'm glad it's working fine; the rest is just precise adjustment, which is also difficult.

[nasios]

Yes, it's operating at high power. The coil might be unsuitable; it's wrapped in paper. The diameter is 10 cm, the resistance is 1 ohm, and the wire diameter is 0.6 mm. After adjusting the frequency, it's indeed much more normal; a 2W high resistance can be detected at around 5 cm. I'm glad it's working fine; the rest is just precise adjustment, which is also difficult.

i think you have try with other coil bigger size and maybe bigger wire 0.8
before many year i build a coil for demagnetization and make noise, after i use bigger wire is stop, i am not sure if you are in same problem but i say maybe is this

[ZOUjiarui]

The inductance is only 460uH, while Eric's data shows 500uH and 1.5Ω, which should be the specifications for a large coil. I was originally using a 1-meter long 30-core cable with 0.5mm² copper cores per strand, an inductance of 520uH, and 1.2Ω, and it also had noise; I suspect it had large parasitic capacitance. Now I've disassembled it, and the inductance is only around 420uH. I'll reconnect it and try again. It's also possible that interference from household appliances is causing the problem.

[ZOUjiarui]

A diameter of 0.5 mm² is approximately equal to 0.8 mm; I will try again. We cannot find any information about the original small coil.

[ZOUjiarui]

The depth is good, but the coil waveform is not quite normal.https://youtube.com/shorts/6s5XVtqB-...RGd4gyDwIWXTUD

[ZOUjiarui]

https://youtube.com/shorts/6s5XVtqB-vM?si=szICPJaxbzlC65FC

[ZOUjiarui]

https://youtube.com/shorts/baPQpnV0dMY?si=BOJGUrRl3_0wKN-z

2

[GeoMax]

Can you change the time base on your oscilloscope? Then you can see better the coil decay path. Maybe the damping resistor is not right.