Fig. 1
Basic MOSFET Transistor Test Circuits
by Lewis Loflin
Updated version on this subject: Test Power MOSFET Transistors, Results, Observations
See the video Simple Circuits for Testing MOSFET Transistors.
In many of the projects on this website and my YouTube videos I use 5-volts with either an Arduino or Microchip PIC to switch on power MOSFETs. The question becomes does 5-volts switch on such a MOSFET? What if the specification sheet for the device the graphs create a doubt? What if one uses a different MOSFET?
The circuit designs above allow those without access to sophisticated test instruments check the gate turn on voltage for any MOSFET. The Zener diode limits the gate voltage where most have a max Vgs of 20-volts. Check the spec sheets for max Vgs!
If one wants to use a 12-volt power supply change B1 and B2 to a single 12-volt light bulb. The Zener diodes and 5.2K resistors can be eliminated.
Most of the test I conducted on various power MOSFETs most switched on around 3.6-4.0 volts.
Update Dec. 2019. Many micro-controllers today are using 3.3-volt Vcc. This is also true of Raspberry Pi. I found two MOSFETs that work at 3.3-volts.
The IRFZ44N is an N-channel device rated at 55V and RDS(on) resistance of 0.032 Ohms max. The other is a P-channel device rated at 55V and a RDS(on) of 0.02 Ohms max.
See the following spec sheets:
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