Fig. 1
Basic MOSFET Transistor Test Circuits
by Lewis Loflin
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.
Updated version on this subject: Test Power MOSFET Transistors, Results, Observations
See the video Simple Circuits for Testing MOSFET Transistors.
See the following spec sheets:
- N-Channel Power MOSFET Switching Tutorial
- P-Channel Power MOSFET Switch Tutorial
- H-Bridge Motor Control with Power MOSFETs
- More Power MOSFET H-Bridge Circuit Examples
- Build a High Power Transistor H-Bridge Motor Control
- Basic MOSFET Transistor Test Circuits
- High Voltage MOSFET Switching Circuits
- LM317 Adjustable Voltage, Current Boost Power Supply
- Constant Current Circuits LM334, LM317
- Build LM317 0-34 Volt Power Supply
- LM334 Constant Current Source with Resistive Sensors
- LM317 High Power Constant Current Source Circuit
- LM317 Constant Current Source Circuits
- Test SCRs and Triacs
- 3 Amp LM741 Op-Amp Constant Current Source
- Current Limiter Testing of Zener Diodes
- Current Limiter for Opto-Coupler Inputs
- LM317 CCS for Light Emitting Diodes
- Experiments with TL431 Shunt Regulator
- TL431A Precision Current Regulator Circuits
- TL431A Based Current Limiter Constant Current Source Circuits
- TL431A Shunt Regulator Circuits
- Using TL431A Li-Ion Battery Charger Tutorials
- TL431A Lithium-Ion Cell Charging Circuits
- Charging Multi-Cell Lithium-Ion Battery Packs
- TL431 Over-Voltage, Under-Voltage Detector Circuits
- TL431A Constant Current Source Working Circuits Demo
Related YouTube video TL431A Lithium-Ion Cell Charging Circuits
Related YouTube video TL431 Battery Charger Circuit Calculations Revised
Related YouTube video TL431 10-Volt Charger Short Version
Related YouTube video Charging, Charge-Balancing 18V Li-Ion Battery with TL431
Related YouTube video 18.5V Li-Ion Battery Charger with TL431 (short)
- Arduino Measures Current from Constant Current Source
- Constant Current Source Theory Testing
- Arduino Controlled Power Constant Current Source
You Tube Videos
- Adjustable LM317 High Power Current Source
- Current Boost LM317 Adj. Power Supply
- LM317 Constant Current Source Circuits
Other Circuits
- Hall Effect Magnetic Switches and Sensors
- Comparator Theory Circuits Tutorial
- ULN2003A Darlington Transistor Array with Circuit Examples
- Transistor-Zener Diode Regulator Circuits
- AC Power Supply Rectification
- Coils for Highly Selective Crystal Radio
- Neon (NE-2) Circuits You Can Build
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- Photodiode Op-Amp Circuits Tutorial
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