When buying field-effect transistors, you can purchase a fake.The fake will be like a field-effect transistor, but the real characteristics will be worse than the original transistor.Such a transistor will fail very quickly or will not work well in the device.How to distinguish an original transistor from a fake one?
To do this, you need to check the input capacitance of the transistor and compare it according to technical data.If the capacity is much smaller than the original one, then you have a fake in front of you.The fake transistor has a smaller crystal, so its input capacitance is smaller.And if the crystal is smaller, then the drain current will also be smaller.
I bought two IRF3205 transistors, one is more expensive and the other is cheaper.An expensive transistor has an input capacity of about 4300pF, a cheap transistor will have a capacity of about 1500pF.
I broke the transistors and you can see that the expensive transistor crystal has dimensions of about 4.5*4 mm
The crystal of a cheap transistor is smaller, about 2mm*2mm
Here is what should be noted.This applies to high-voltage field-effect transistors.You can buy a fake, and its input capacity will be about the same as the original, but the transistor will fail.The fake crystal will have the dimensions of the original.What’s the matter? And the fact is that you were sold a low-voltage transistor, which is cheaper than a high-voltage one
