Creators
Rojony Khatun Author
Rojony Khatun
CalculatorToolsProjectExpert
Reviewers
Małgorzata Koperska, MD Steven Wooding
Last updated: January 14, 2026

MOSFET Tester Circuit Using IRFZ44N for Electronics Projects

🇺🇸
English
Default
🇪🇸
Español
Spanish
🇫🇷
Français
French
🇩🇪
Deutsch
German
Mini Push Button Switch

Mini Push Button Switch

A simple mechanical switch used to make or break a circuit when pressed. It returns to its original position once released. Commonly used in doorbells, calculators, reset buttons, and control panels.

220µF Capacitor

220µF Capacitor

Medium-value film or ceramic capacitor for AC/DC circuits

270-ohm Fixed Resistor 1/4W

270R Fixed Resistor 1/4W

A 270-ohm resistor rated for 0.25 watts

22K Fixed Resistor 1/4W

22K Fixed Resistor 1/4W

A 22,000-ohm resistor rated for 0.25 watts

3V LED 5mm

3V LED 5mm

3V, 5mm round light-emitting diode

*Please note: These are affiliate links. I may make a commission if you buy the components through these links. I would appreciate your support in this way!

How Make MOSFET Tester

Test IRFZ44N MOSFETs easily with this simple MOSFET tester circuit. Ideal for hobbyists, students, and DIY electronics projects to check MOSFET functionality.

transistor and MOSFET checker

MOSFET tester IRFZ44N is a tester that enables it to check the switching capacity and functionality of the MOSFETs. It also shows gate control, load conduction, and MOSFET testing concepts of home-made electronics work.

diy electronics projects​

A dimmer circuit for a 220V AC fan is a simple and effective way to change the speed of ceiling or table fans in your home. You can change the firing angle of the AC voltage to change the fan speed smoothly with a TRIAC and DIAC triggering circuit. This saves energy, makes the fan last longer, and lets users choose how comfortable the airflow is. The circuit is small, easy to put together, and great for people who like to build their own electronics. This guide will show you how to build a reliable fan dimmer circuit by going over the parts you need, the circuit diagram, how it works, how to put it together, and safety tips. You can control the speed of a 220V AC fan smoothly without damaging the appliance or putting yourself at risk of electric shock if you follow the instructions carefully.

Features of the 220V Fan Dimmer Circuit

Smooth Fan Speed Control

  • Gradual adjustment from low to high speed.
  • Minimizes flicker or jerky fan movement.

Energy Saving and Efficiency

  • Reduces power consumption at lower speeds.
  • Extends fan motor life.

Compact and Easy to Build

  • Small PCB design.
  • Low component count, ideal for DIY projects.

Components Required

TRIAC (e.g., BTA16, BT136)

  • Acts as a switch to control the AC load.
  • Requires proper heat sinking for safe operation.

DIAC (e.g., DB3)

  • Provides triggering pulse for TRIAC.
  • Ensures smooth conduction and reduces voltage spikes.

Potentiometer (AC Rated)

  • Adjusts phase angle, controlling the fan speed.
  • Typically 500Ω to 1kΩ, AC-rated.

Resistors and Capacitors

  • Resistor-capacitor (RC) network sets TRIAC triggering delay.
  • Ensures smooth fan speed transition.

Heat Sink

  • Dissipates heat generated by TRIAC during conduction.

Working Principle

Phase Control Using TRIAC and DIAC

  • TRIAC acts as a bidirectional AC switch.
  • DIAC triggers the TRIAC once the capacitor voltage reaches its breakover point.

Triggering Circuit for Adjustable Firing Angle

  • Potentiometer and RC network adjust the charge time of the capacitor.
  • Faster or slower charging changes the TRIAC firing angle.

Voltage and Speed Control of AC Fan

  • TRIAC switches the AC voltage to the fan motor at different points in the cycle.
  • Effective AC voltage varies, controlling fan speed.

Circuit Diagram and Assembly Steps

AC Input Connections

  • Connect live and neutral lines from the mains supply to the circuit input.
  • Ensure proper insulation and fuse protection.

AC Input Connections

  • Connect live and neutral lines from the mains supply to the circuit input.
  • Ensure proper insulation and fuse protection.

TRIAC and DIAC Trigger Circuit

  • Connect the DIAC in series with the capacitor and potentiometer to the TRIAC gate.
  • TRIAC MT1 and MT2 terminals connected to the AC fan and mains.

Potentiometer Adjustment

  • Adjust the potentiometer to vary the charging time of the capacitor.
  • Smoothly controls TRIAC conduction angle, adjusting fan speed.

Testing and Fine-Tuning

  • Power ON circuit without a fan to check firing pulses.
  • Connect the fan and adjust the potentiometer gradually.
  • Ensure TRIAC stays within temperature limits.
  • Observe smooth speed control and check for noise or flicker.

Applications

  • Household ceiling or table fans
  • Small AC appliances requiring speed control
  • Energy-saving home automation projects
  • DIY electronics learning projects

Safety Precautions

  • Ensure mains power is OFF during assembly.
  • Use insulated tools and AC-rated components.
  • Keep TRIAC on the heat sink to avoid overheating.
  • Fuse or circuit breaker for protection.
  • Avoid touching live wires while operating.

Troubleshooting and Maintenance

  • Fan not running: Check TRIAC and DIAC connections.
  • Fan running erratically: Inspect RC network and potentiometer.
  • Overheating TRIAC: Add a larger heatsink or reduce the load.
  • No speed variation: Potentiometer may be faulty or incorrectly rated.

Frequently Asked Questions - How Make MOSFET Tester:

What is IRFZ44N?

It is an N-channel power MOSFET used for switching and amplification.

Can this tester check any MOSFET?

Yes, similar N-channel MOSFETs can be tested.

What voltage is required?

Typically 12V DC, depending on MOSFET rating.

Do I need a load?

Yes, LED or small motor to observe conduction.

Is it beginner-friendly?

Yes, simple circuit with minimal components.

Can I test multiple MOSFETs?

Yes, one by one using the same setup.

Do I need a heatsink?

Optional for low current testing.

How to apply gate voltage?

Using a resistor or small DC supply to MOSFET gate.

Can it damage the MOSFET?

No, if gate voltage and load current are within ratings.

Applications?

Checking MOSFET functionality before using in circuits.

Comments

Please login to comment.

Rojony Khatun

Rojony Khatun

Calculator Tools Project

Rojony Khatun is the creator of a free online tools website designed to simplify everyday and engineering-related calculations for students, professionals, and hobbyists. The platform offers a wide variety of basic and advanced calculators across key categories, including Electrical Calculators, Electronic Calculators, and Time & Date Calculators, helping users solve problems quickly and accurately.