WARNING! This induction heater produces hundreds of volts across its output. DO NOT touch the circuit OR workcoil while powered on! Or you risk being electrocuted! Once the power is switched off, the capacitor bank instantly discharges and the circuit is safe to work on. Downloads: Circuit Schematic PCB Gerber Files Watch Build Video Specifications: PCB Size: 86 x 284mm Input voltage: 40~65VDC Max input current: 50A Max power consumption: 3,250watts Assembling the PCB You’ll find all the components & their specifications listed below. You can download a detailed schematic to identify what component goes where on the PCB. PCB Components: C1~14 – 330nF 600VAC Capacitors C15, C16 – 2.2uF 100V Ceramic Capacitors D1, D2 - 12V 5W Zener Diode D3, D4 – FR307 Fast Diode D5 – 5mm LED D6 - SB5H100 200A 100V Schottky Diode L1, L2 – 60uH 25A Custom made inductors ( watch video ) R1, R3 – 150R 5W Metal Oxide Resistor R2, R4 – 1K 5W Metal Oxide Resistor R5, R6 – 10K 1/2W Metal Oxide Resistor R7 – 4.7K 1/2W Metal Oxide Resistor R8, R9, R10, R11 – 18R 1/2W Metal Oxide Resistor Q1, Q2, Q3, Q4 - IRFP4668PBF MOSFET Bolstering the PCB traces The traces on the PCB that are exposed on the underside need to be bolstered by either cutting out copper busbars from a sheet of copper (1.5mm or thicker) Or by using 14AWG, 2.5mm core electrical cable, soldered to the PCB traces. I used the latter method in the build video, and although it’s not very aesthetically pleasing. It’s proven to work without any issues Workcoil Design The workcoil is the business end of all induction heaters. When it comes to designing a workcoil several design elements should be taken into account. This is an area where I’d admit, I’m still learning myself, so I don’t consider my advice on this topic to be all that helpful. But, a good starting point is to have a workcoil with 6 turns of 3/8” copper tubing to make the workcoil. The internal diameter should be around 10~20mm larger than the piece of metal you’re intending to heat. Using a workcoil that has a much larger diameter than the piece of metal you’re heating, will reduce performance & lead to longer heat times. The air gap between turns has a significant role in determining the input current consumption and power output. Increasing the air gap also increases input current consumption. And the opposite is also true, smaller airgap = lower input current consumption. Calculating the correct air gap on paper before you construct your workcoil is very doable however, it's also possible to use a trial & error method. Start by keeping the windings tight (around 2mm air gap), operate the induction heater, and monitor the current consumption, if you wish to increase the current, then gently spread the winding further apart to increase the airgap. You can repeat this process until you achieve your ideal power input/output. (Don't forget to have the induction heater OFF while making alterations to the workcoil) A company called ‘Ambrell’ published a 28-page guide around workcoil design. You can request a free copy of their guide by using this link Click Here (They do ask for your name & email, but it’s 100% free) Cooling During normal operation, the MOSFET heatsinks & capacitors will get hot! You will need to use a fan to blow air over the components to keep the temperatures at acceptable levels. For runtime more than 30 secs or so, the workcoil will get very hot. I’d highly recommend cooling the workcoil by continually pumping water through it. Printed Circuit Board Order your own custom printed circuit board using the files below: Download PCB Gerber Files Inductors I made my own custom inductors for this project. I used a total of 4x T157-26 Inductor Toroid Rings. Each inductor has 2 toroid rings stacked on top of one another. I have found this to be the most cost-effective solution for this project. A total of 16 turns of 2mm (12AWG) magnet wire is wrapped around the toroids to produce an inductor with approximately 60uH of inductance. You can customize the inductance by adding or subtracting turns around the toroids. If you’re heating smaller pieces of metal, to maximize power output from the induction heater into the piece of metal you’re heating, you may want to consider lowering the inductance to around 30~40uH. Similarly, the inverse is true. If you’re heating large pieces of metal & your induction heater is drawing more current than the maximum allowed (50A) Then increasing the inductance to 60~200uH will bring the input current down to a safe level. If you’re using 2x T157-26 stacked together, below is a cheat sheet to quickly customize the inductance. Number of turns for inductance: 36uH = 13 Turns 60uH = 16 Turns 100uH = 21 Turns 150uH = 26 Turns 200uH = 30 Turns Alternatively, you can use this calculator to help you customize the inductance Components: 4x T157-26 Inductor Toroid Ring · Size: 40x24x15mm · Material: Iron Powder · Magnetic Permeability: 75 4x Wakefield-Vette 694-5 MOSFET Heatsink · Size: L:50 W:22 H: 35mm · To fit: TO-247 package 14x WIMA MKP1O133306F00KSSD 330nF 600VAC Capacitors · Size: L: 31.5 W: 15 H: 26mm · Lead Spacing: 27.5mm · Voltage: 600VAC, 1000VDC · Capacitance: 330nF 2x TDK FG20X7R2A225KRT06 2.2uF 100V Ceramic Capacitors · Size: L:7 W: 5.5 H: 4mm · Lead Spacing: 5mm · Voltage: 100VDC · Capacitance: 2.2uF 2x ON Semiconductor 1N5349BRLG 12V 5W Zener Diode · Package: 017AA-2 · Power: 5W · Zener Voltage: 12V 2x Rectron FR307-B Fast Diode · Package: DO-201AD · Voltage: 1000V · Current: 3A · Type: Fast recovery 500ns 1x 5mm LED · Forward Current: 20ma · Regular Through hole 5mm LED · Color of your choosing 1x Vishay SB5H100-E3/54 Schottky Diode · Package: DO-201AD · Voltage: 100V · Surge current: 200A 2x 150R 5W Metal Oxide Resistor · Size: L: 17.5 D: 6.5mm · Power: 5W 2x 1K 5W Metal Oxide Resistor · Size: L: 17.5 D: 6.5mm · Power: 5W 2x 10K 1/2W Metal Oxide Resistor · Size: L: 6.5 D: 2.5mm · Power: 1/2W 1x 4.7K 1/2W Metal Oxide Resistor · Size: L: 6.5 D: 2.5mm · Power: 1/2W 4x 18R 1/2W Metal Oxide Resistor · Size: L: 6.5 D: 2.5mm · Power: 1/2W 4x IRFP4668PBF MOSFET · Package: TO-247-3 · N-Channel MOSFET · Vds: 200V · Id: 130A · Rds On Resistance: 9.7mOhms Other Components & hardware: · 3.2meters (11ft) of 2.0mm (12AWG) Magnet Wire (aka ‘enamel copper wire’) for winding the inductors · 2~3 meters of 3/8” Copper Tubing to make workcoil · 2mm (14 Gauge) thick Copper sheet to cut into PCB busbars OR 2.5mm core electrical cable to solder to PCB traces

Resources: Build & demo video: Click here Coil form tool Download STL file PCB Gerber files Download gerbers Schematic Download Schematic Details: Voltage input: 12~48VDC Current input: up to 30A (@48VDC) Peak power input: 1,400watts The Circuit This induction heater is based on the popular "Royer induction heater" schematic. I believe this is the original post/author? Click here Changes made to the design include: Higher rated MOSFETs Bigger Zener diodes RC filter on the Gates Flyback Diode (D8) Gate resistors to limit ringing (R8, R9) In short, all of the changes help to improve the durability of the induction heater. It has been reported with the original design, often the MOSFET gate's would be damaged from flyback after extended use. To be fair, I haven't tested the circuit without my additions so I can't confirm or deny this. Gate resistors have to be added as ringing was quite a problem without them. The ringing would cause the MOSFETs to become quite hot & this can lead to premature failure. With the addition of a pair of 18R gate resistors. The ringing was reduced to an acceptable level. Components: 2x Wakefield-Vette, 694-50 Heatsink Click here 2x IRFP4668PBF MOSFETs Click Here 10x WIMA, MKP1J034706B00KB00, 470nF, 630VAC Capacitor Click here 2x 2.2uF Ceramic 100v Capacitor Click here 2x FR307 Fast Diode Click here 2x 47R, 5w Metal Oxide resistor Click here 2x 470R, 5w Metal Oxide resistor Click here 2x 12v, 5w Zener Diode Click here 1x SB5H100 Schottky Diode Click here 2x 100uH, 15A inductor Click here (see below for details) 2x 10k, 1/2w resistor 1x 4.7k, 1/2w resistor 1x 5mm LED of your choice (power indicator LED) The inductors For the inductors, I opted to wind my own. Options for this size are somewhat limited & it was cheaper to make my own anyhow. If you don't wish to make your own, then alternatively you can buy them from banggood Click here Toroid details: Size: 42x22x17mm Material: Iron Powder, HY2 Color Code: Yellow/White For the wire, I used 1.25mm (16AWG) enamel insulated copper wire. Each toroid used approx 1.6m (63inch) of wire. This length of wire yields 30~32 turns around the toroid giving an approx inductance of 100uH. Tinning the high current traces Located on the underside of the PCB is several exposed traces that should be tinned with PLENTY of solder after all the components have been installed. These traces carry very high current that pulses through the work coil. Failure to adequately bolster these traces with copious amounts of solder will result in the solder melting off the PCB, which will result in the trace burning out, which in turn blows up one of the MOSFETs (not that I'd have done anything like that :P ) I'd recommend laying down some fairly heavy copper wire on top of the traces & solder it in place just to be on the safe side. The Coil This is the work coil. I made my coil from 3/8" copper tubing (the type used for aircon, fridges.etc) It's pretty inexpensive & easy to find at most hardware stores or aircon shops. The inside diameter of my coil is 70mm to accommodate almost anything I'd need to heat. The coils consist of 6 & 1/2 turns. The amount of turns does play a role in determining the resonating frequency (and also power output/consumption). If you know what you are doing & are willing to experiment with different coils, then go for it. Otherwise, I'd suggest making a coil with 6~8 turns. If you watched my build video, then you'll have seen me 3D print a form tool, used to wrap the copper around to form the coil into a spiral. Strictly speaking, It's not essential however, it does produce a nice uniform coil. You can download the STL file Here Performance With a 48V power input and a 140mm PC fan blowing air over the heatsinks & caps. Temperatures were quite acceptable at 80c (176f) for the MOSFETs, the capacitors were about the same. And the inductors never felt even slightly warm. I think for higher input voltages (above 48VDC) You'd have to start considering spacing the caps further apart for better cooling & depending on how far you push the envelope.... maybe water cooling the MOSFETs & work coil. Will it melt Aluminum? The original author demonstrates his induction heater melting an aluminum heatsink. I've attempted to melt alloy in my induction heater and it failed to do so. I'm not exactly sure why he was able to melt alloy and I was not but, I do wonder if he is tuning up his power input to achieve this? He seems to indicate this in his post. It's also possible different alloy's melt easier than others so perhaps this is something I'll explore later. What would it take to make this induction heater more powerful? In truth, the components used could probably handle 60V (just monitor the peak voltage across the caps & make sure to stay within their max voltage rating). However, at higher power levels, you certainly need to bolster the high current traces on the PCB to prevent failure. Keeping the caps & MOSFETs within temperate limits could also be a challenge. Perhaps water-cooling would be a viable solution? In any case, it's certainly possible for this circuit to handle higher voltage than 48VDC if appropriate measures are implemented.

Complete How-To-Build video: https://youtu.be/doCg0k0m-dA Description: This project came about because I wanted to have a cordless fume extractor. The extractor can be powered from either a 12VDC wall adaptor Or 3x 18650 lithium batteries making it rather unique. To prevent the batteries from being over-discharged & to prevent both power sources from competing to drive the fan, a low volt disconnect I build in another video is used. You can learn more about the Low-Volt-Disconnect here . If both power sources are present, by default the fan will run from the batteries. In an ideal world, I'd prefer the power adaptor to be the default power source. But hey, in reality, I'm only going to use the pwr adaptor as a back up if the batteries run flat. Selecting a high-performance 140mm fan is very important. The fan I used can be found below under components. However, you could select any other fan with similar performance figures. For comparison, these are the specs of the Noctua fan I used: Airflow: 158.5 CFM Static pressure: 10.52 mmH20 How effective is the filtration? That’s a good question. I don’t have specialized equipment to measure the air quality, however, I’m certain it doesn’t filter everything since I can visibly see some smoke exhaust out the back of the extractor. So does that mean it’s useless? Well not in my opinion. In my workshop, all I had to do was prevent the smoke from concentrating around my immediate work area. And this fume extractor does just that, it sucks away the concentrated smoke and blows it away from my work area. The housing for this project is entirely 3D printed. And the 3D files can be found here: https://www.thingiverse.com/thing:4597398 3D Print one of each except for the enclosure files. You only need to print a single enclosure and you must choose one that suits your power switch size, there are 16mm, 19mm & 22mm variants and there is also the option to print an enclosure that doesn't have any switch or DC power jack holes. This way you can print the enclosure and dill/cut holes to suit your hardware. If you purchase any products using the affiliate links below, you are helping support my content and that makes you awesome! 😎 Components: Noctua Industrial 140mm Fan, 3000rpm: https://amzn.to/3mv9R0r Carbon filter sheet (cut down to 138x138mm): https://amzn.to/2Flp837 3S 18650 battery compartment: https://ebay.to/3hxUXCA 16mm DPST On/Off switch: https://ebay.to/3kjVhHa 5.5x2.5mm DC power jack, female, panel mount: https://ebay.to/3c13ywC SB540 Schottky diode: https://ebay.to/3mwWvke Low volt disconnect: https://www.schematix.co.nz/forum/how-to-s/low-volt-disconnect-project Optional: 12VDC, 1A wall adaptor: https://amzn.to/3c1maN1 Hardware: 8x 4g 12mm countersunk, self-tapping screw (used to assemble the enclosure) 4x M4x40mm countersunk, screw (used to mount fan) 4x M4 nyloc nuts (used to mount fan) 4x 4g x 6mm pan head screws (Mount LVD to enclosure) 4x PC fan screw (secures the battery compartment to enclosure cover) Wiring Diagram: