Testing MOS-FET with Multimeter.

[Krister Persson]

I have problems when testing a Nch MOS-FET. I have learned how to do it on YouTube. However after I have touched the gate with the red pin the MOS FET does not close and I get no readings between the drain and the source.
The gate threshold voltage (Vth) on this particular MOS FET ls Min 3V and Max 4.5V. I have a FLUKE 75 Multimeter.
Can it be that the voltage on the pins are to low to close the MOS FET? And what voltage is it on the pins?
When I think about it, this is maybe not the right forum to ask electronics questions?

 

[mainline]

I have problems when testing a Nch MOS-FET. I have learned how to do it on YouTube. However after I have touched the gate with the red pin the MOS FET does not close and I get no readings between the drain and the source.
The gate threshold voltage (Vth) on this particular MOS FET ls Min 3V and Max 4.5V. I have a FLUKE 75 Multimeter.
Can it be that the voltage on the pins are to low to open the MOS FET? And what voltage is it on the pins?
When I think about it, this is maybe not the right forum to ask electronics questions?

Have you measured the mosfet ? can you measure the a parasitic diode ?

You may need to drive the gate with more voltage, especially if it's a fake one.

 

[Krister Persson]

Have you measured the mosfet ? is there a parasitic diode ?

You may need to drive the gate with more voltage, especially if it's a fake one.

I have measured it stand alone. It's not on a board. What do you mean if it's a fake one?

 

[mainline]

I have measured it stand alone. It's not on a board. What do you mean if it's a fake one?

A copy of original ones, usually Chinese copies.

Take a look at these, do you have a power supply.

View: https://www.youtube.com/watch?v=XXcEgddzjnI

View: https://www.youtube.com/watch?v=ElTTOsj3y-Q

 

[Avo Mk8]

O

Can it be that the voltage on the pins are to low to open the MOS FET? And what voltage is it on the pins?

The Fluke 75 uses a constant current source when measuring resistance, which seems to typically provide just microamps.
A random Google suggests the max voltage on meter pins doing resistance measurements is 3V, so it may not be enough to switch the mosfet.

 

[Krister Persson]

A copy of original ones, usually Chinese copies.

Take a look at these, do you have a power supply.

View: https://www.youtube.com/watch?v=XXcEgddzjnI

View: https://www.youtube.com/watch?v=ElTTOsj3y-Q

Oh my Gosh! I bought them from AliExpress - China so I guess they are fake then? But they don't look like in your linked video. I attach a picture so you can see. The left one is supposed to be a STP4NK60Z and the right one a 2SK3868. No I haven't a power supply so I can't measure them.

 

[mainline]

Oh my Gosh! I bought them from AliExpress - China so I guess they are fake then? But they don't look like in your linked video. I attach a picture so you can see. The left one is supposed to be a STP4NK60Z and the right one a 2SK3868. No I haven't a power supply so I can't measure them.

If they were very cheap then i doubt they are genuine, but should work just to a much lesser degree than an original one.