Low-Power Induction Heater using ZVS Oscillator

Induction heating is how industry hardens gears and solders without flame: a high-frequency magnetic field induces eddy currents in the metal, and the metal's own resistance turns those currents into heat. The ZVS oscillator is the hobbyist-grade route to the same physics — a self-resonating push-pull stage that switches its MOSFETs at zero voltage, keeping switching losses low enough for a student build. This project constructs one: a center-tapped copper work coil, two power MOSFETs with heatsinks, resonant tank capacitors, and a 12–24 V supply. A K-type thermocouple with a MAX6675 module and LCD show the workpiece temperature climbing, so the demo is quantitative, not just "it glows". The report works through resonance, skin effect and eddy-current heating, and the safety section is treated as first-class content, not a footnote.

1. The 12–24 V DC supply powers the ZVS stage; on switch-on the oscillator self-starts, alternately driving the two MOSFETs.
2. The MOSFETs drive the center-tapped work coil in push-pull; the tank capacitors and coil inductance set the resonant frequency (tens of kHz, design target).
3. The high-frequency alternating magnetic field inside the coil induces eddy currents in the inserted steel workpiece.
4. The workpiece's own resistance converts the eddy currents to heat — the metal temperature climbs with no contact and no flame.
5. The K-type thermocouple pressed near the workpiece feeds the MAX6675; the Arduino displays live temperature on the LCD.
6. The student varies the tank capacitance and supply voltage (within ratings) and records the heating rate for the report's resonance study.

Tech stack:

• ZVS oscillator (2x IRFP250-class N-MOSFETs)
• Hand-wound copper-tube work coil, center-tapped
• Resonant tank capacitors (selectable)
• K-type thermocouple + MAX6675 module
• Arduino Nano + 16x2 LCD (temperature display)
• 12–24 V DC supply, input fuse, heatsinks + fan

• [ZVS resonant driver] Classic zero-voltage-switching push-pull oscillator (two IRFP250-class MOSFETs) self-resonates with the tank capacitors — efficient switching the student can probe on a scope.
• [Hand-wound work coil] Copper-tube work coil, center-tapped, sized for the tank resonance — the student winds it and learns the inductance-capacitance relationship firsthand.
• [Contactless heating demo] A steel bolt or similar workpiece placed inside the coil heats via eddy currents with no electrical contact and no flame.
• [Live temperature display] K-type thermocouple + MAX6675 module and 16x2 LCD show the workpiece temperature in real time during the heating demo.
• [Resonance tuning] Tank capacitors are selectable so the student tunes the resonant frequency and observes the effect on heating rate.
• [Over-current protection] Input fuse and MOSFET heatsinks with a fan; firmware-free analog design keeps the protection simple and visible.
• [Safety-first documentation] Rated as a supervised lab demo: workpiece handling procedure, burn and EMI precautions, and a mandatory cool-down routine.

• Working ZVS induction-heater prototype (driver board, work coil, thermocouple, display)
• Arduino temperature-display firmware
• Wiring diagram, coil-winding guide and tank-capacitor selection table
• Resonance-tuning and heating-rate test procedure
• Safety guide (burn, EMI, supervision, cool-down routine)
• Project report PDF (resonance, skin effect, eddy currents, test results template)
• PPT presentation for final review
• Viva Q&A preparation document

• Low-power educational demo only — it heats small steel items; it is not a hardening furnace and cannot melt metal.
• Runs on 12–24 V DC at up to ~10 A: high-current wiring must be respected, and the demo is strictly supervised with the cool-down routine.
• The work coil and workpiece get hot enough to burn — handling procedure in the safety guide is mandatory.
• Generates strong high-frequency EMI near the coil; keep sensitive electronics and magnetic media away during the demo.
• Only ferromagnetic workpieces heat efficiently; aluminum and copper barely respond at this power.
• Heating rate figures are buyer-measured during their own test — no heating performance is claimed in advance.