So I'll ask here only because it's relevant to what I'm doing but If I only have multi meter and common electrical stuff how do I determine N or P type MOSFET? And 250khz? Are they all that fast or do I need special type there?
For testing Through Hole Power Mosfets. For small MOSFETs the pin orientation may be different. To determine orientation, with multimeter in diode test, connect the probes to different pins until you get a voltage reading of the body diode.Body Diode reading can anywhere between 0.3V to 1V depending on MOSFET. Those 2 pins are the Drain and Source Small MOSFETs the gate is usually the centre pin.
Set your multimeter to diode. With the pins toward you, Power MOSFET pin orientation will be from left to right Gate Drain Source. For this test "Clip" = "Probe"
Take appropriate ESD precautions.
N-Channel
Attach the Multimeter Positive to Drain and Negative to Source.
For N-Channel you should get a reading OL . If you get a reading then it's the body diode and it a P-channel. Go down to P-Channel testing
With Negative Source clip attached move the Positive Drain clip to Gate. This will charge the gate. Then move that clip back to Drain. You should get a voltage reading at 0V or near 0V. With finger and thumb, touch the gate and source pins. Reading should go to OL again.
P-Channel
Attach the meter clips Positive to Source and Negative to Drain.
For P-channel you should get a reading OL. If you get a reading then it's the body diode and it's N-Channel. Go to N-Channel testing.
With Positive Source clip attached, move the Negative Drain clip to the Gate. This will charge the gate. Then move the clip back to Drain. You should get a voltage reading of 0V or near 0V. With finger and thumb, touch the Gate and Source pins. Reading should go back to OL again
For very large MOSFETs you can use a 9V battery to charge the gate. A used 9V battery will also work.
Simply determine what polarity the Drain and Source clips should be attached to pins according to the previous test. Take 9V battery and touch the Gate and Source. By changing the orientation of the battery, the transistor will turn On or Off (OL) when you observe the multimeter.
Do Not use a 9V battery on small MOSFETs as some have very low VGS and could be damaged. For small MOSFETs, simple using your finger and thumb from gate to either the source or drain is plenty enough to charge and discharge the gate.
If any of these procedures fail then recheck with the Ohms setting to see if the MOSFET is shorted.
I train many people in my field and tend to be very precise and repetitive. Don't take it the wrong way.