Build a High Voltage Flyback Driver Using IRFP250N and DIY Frequency Generator (25kV Output!)

Ever wanted to generate jaw-dropping high voltage arcs at home? In this project, I’ll walk you through how I built a DIY high voltage flyback driver that outputs around 25,000 volts, using common components like the IRFP250N MOSFET, a 2N2222 transistor, and a homemade frequency generator I built earlier and shared on Instructables.

We’ll go deep into how this circuit works, why I made certain design choices, and how you can improve it. Expect flying sparks, a lot of learning, and yes — a solid 2.5 cm arc.

Disclaimer

WARNING: This project involves dangerously high voltages (25kV+), which can be lethal if mishandled. Do not attempt this unless you have prior experience with high voltage electronics. Always work in a dry area, wear rubber gloves, and never touch the transformer while it’s powered. Keep flammable objects away and work in a ventilated area.

IRFP250N MOSFET : 1

2N2222 Transistor : 1

Flyback Transformer (from old crt tv or buy one its very cheap ) : 1

1kΩ Resistor : 1

10kΩ Resistor : 1

100Ω Resistor : 1

DC Power Supply (12–24V) : 1

Thick Wire (for primary) : 1–2 ft ( around 7 turns)

DIY Frequency Generator : 1 (For How to make it checkout mt previous post)

Heatsink : 1

Frequency Generator (The Brain)

A few days ago, I shared a separate Instructable about a DIY frequency generator I built inside a 3D-printed orange case. That project is the heart of this setup.

Key Features:

1. Adjustable frequency (tested at 1hz to 20000hz)
2. Modes: Manual, Sweep, Step, and Continuous
3. Controlled via tactile push buttons: MODE, UP, DOWN, STEP, SWEEP, OUT
4. Output: Square wave at 3.3V logic level

This signal is too weak to drive a power MOSFET directly, so I added a transistor level shifter in the next step.

Most flyback transformers have a built-in primary, but it's designed for 100+V direct DC. At 12–24V, it's inefficient.

So I wound my own 7-turn primary coil using thick wire directly on the ferrite core. This gave me better control, efficiency, and reduced heating.

Frequency Generator to Gate Driver:

1. Frequency Generator Output Pin (3.3V square wave) ---> 1kΩ resistor ---> Base of 2N2222 transistor
2. use 8000hz for best result

2N2222 Transistor:

1. Emitter (Pin 1) ---> GND
2. Base (Pin 2) ---> From 1kΩ resistor connected to frequency generator output
3. Collector (Pin 3) ---> One end of a 100Ω resistor ---> IRFP250N Gate (Pin 1)

Also:

1. Connect a 10kΩ resistor from IRFP250N Gate (Pin 1) to +12V (this ensures full high logic)

IRFP250N MOSFET:

1. Gate (Pin 1) ---> From collector of 2N2222 (through 100Ω resistor)
2. Source (Pin 3) ---> GND
3. Drain (Pin 2) ---> One end of the 7-turn primary coil

Primary Coil:

1. Other end of the primary coil ---> +12V from power supply i used a 12v 2amps transformer and rectified it to DC

Flyback Transformer:

1. Use your own 7-turn coil wound on the core as the primary (ignore built-in primary)
2. The high voltage output comes from the internal secondary — one of the thick red wires (usually the one with the suction cup or insulated cable). Leave the other wires disconnected unless you know their internal winding structure.

Use a Gate Driver IC

Replace the 2N2222 with a proper gate driver like IR2110 or TC4420 for faster switching and cooler MOSFET operation.

Add Snubber Circuit

Protect the MOSFET from voltage spikes using a snubber (e.g., 1kΩ + 100nF across drain and source) or a fast diode (UF4007).

Duty Cycle Control

Add a knob or button to adjust the duty cycle. You’ll be able to modulate spark strength and power.

Active Cooling

If running for long durations, add a heatsink and a small 12V fan to keep your MOSFET cool.

This project was an absolute blast to build! I started with just a signal generator and a dream of making sparks fly — and ended up with a solid high-voltage arc generator powered by 12V.

With a bit of care and some common parts, you too can make a safe and powerful high voltage driver at home. Let me know if you build it — and please, be careful!

If you liked this project, drop a comment, vote, or favorite! Thanks for reading — now go make some sparks!