Practical or differential integrator?

[eduardo1979]

Hi Carl.
My MOSFET is an SMD type, an IRF740S, and it's soldered directly to the PCB, just like in the TDI SL. It doesn't have an external aluminum heatsink.

[Carl-NC]

Either you MOSFET has a higher channel resistance or it has a lower breakdown voltage. There is variation in parts.

[eduardo1979]

Thanks, Carl. I'll try other IRF740S. All the electronic components I use are originals purchased from Mouser. If I can't improve the results, I'll try a more powerful MOSFET. I'll try an "IPB65R110CFD7ATMA1" MOSFET.

[Op04]

Hi Altra.
I'm using the same configuration as the TDI SL. I'm not using a resistor in series with the coil, as in the original TDI.
The truth is, I don't understand why the MOSFET in my detector gets hotter than the MOSFET in the TDI SL, even though I'm using the same gate driver, the same frequency (2.8kHz +/-), and the same pulse width (100µs). Perhaps Carl could help me.

Hi Eduardo,

I wonder will you share this project?
there are two FQT7N10 in PSU part makes this up (FET not too hot)

[eduardo1979]

The problem was related to the power supply. My TDI SL is powered by eight 1.5V batteries, and the detector I was building was powered by 12V, 3.6Ah lithium batteries. The batteries don't supply as much current as the lithium batteries, which is why the IRF740S was overheating. I ended up reducing the pulse width to 80µs, and the problem was solved, allowing me to continue using the lithium batteries without the MOSFET overheating. I know the TDI SL has two FQT7N10 MOSFETs in series. I've also added them to my detector, but again, the problem stemmed from excessive current draw.

[Op04]

The problem was related to the power supply. My TDI SL is powered by eight 1.5V batteries, and the detector I was building was powered by 12V, 3.6Ah lithium batteries. The batteries don't supply as much current as the lithium batteries, which is why the IRF740S was overheating. I ended up reducing the pulse width to 80µs, and the problem was solved, allowing me to continue using the lithium batteries without the MOSFET overheating. I know the TDI SL has two FQT7N10 MOSFETs in series. I've also added them to my detector, but again, the problem stemmed from excessive current draw.

Glad it solved, alright then

Edit:
I forgotten since you mention post #18 on another machine back then I have use IPW65R150CFD I was satisfy with it, I also try lower coss FET but less deep, there are still some mystery why some FET not suite