Easy DIY Induction Heater Guide

James Andrews

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8 min read

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Feb 26, 2021

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Figure 1. Using my induction heater to heat up a fork in seconds.

Introduction

Induction heating is so fascinating. The coil is not hot but can still heat any magnetic and conductive object to hundreds of degrees within seconds! The craziest part is that you can get your hands on a device like this for under $15. I have several of them, and I love to show how cool they are on my YouTube, as shown below:

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Background

There are many great industrial uses for induction heating. In the industrial world, induction heating can be used for annealing, welding, forging, etc. Additionally, many bike and auto hobbyists use induction heating to remove old rusted nuts and bolts using a Bolt Buster, although they are somewhat pricey.

I personally think induction heaters are simply too cool of a concept to not have fun with, so I use mine mostly to heat up random objects or cut through food items with a hot knife.

Induction Heating Basics

Induction heating is rather complicated but can be simplified for those without a strong technical background. There are four main concepts you need to understand. If you are more of a visual learner, you may want to check out my YouTube video, where I discuss the following.

Magnetic and Conductive Objects

Induction heating only works with objects capable of conducting electricity and works much better on objects that are magnetic. In order for an object to be conductive, it must have free electrons that are capable of moving around the object. Most metals are conductive. Magnetic objects have a magnetic field around them. Although you cannot see a magnetic field visually, magnetic fields will interact with other magnetic fields. For example, when you place two magnets near each other, they will be pulled towards each other.

Ampere’s Law

When you pass current through a wire, a magnetic field is produced around the wire. The wire was not originally magnetic, but now has a magnetic field. When you wind a coil out of wire and then pass current through it, the magnetic field within the coil is much stronger.

Figure 2. Ampere’s Law

Faraday’s/Lenz’s Law

When you place two opposing magnetic fields next to each other, they affect each other. The electrons within the objects move to become oriented with the new magnetic field. This movement (flow) of electrons is called current.

So, changing the magnetic field of a conductive object will produce tiny currents within the object, known as eddy currents. Once the electrons have finished aligning with the new magnetic field, the electrons become stationary again. There is no more current. In order to continuously produce eddy currents within the object, you must keep changing the magnetic field.

The best way to do this is using alternating current (AC). The direction in which current flows through the coil matters. You can see this by looking at the North and South poles of the induced magnetic field in previous figure above (Figure 1). If you switch the direction of current, the polarity of the magnetic field switches direction as well.

If this AC current has a high frequency, the direction of current flow is switching many times per second, meaning you are changing the magnetic field many times per second. Therefore, the electrons never stop moving and the object constantly produces eddy currents.

Resistance Produces Heat

The final piece to the puzzle is understanding how current produces heat. When the electrons are constantly moving (current), there is a resistance (like friction) that produces heat. This is similar to the way friction creates heat when you rub your hands back and forth. By constantly producing eddy currents, you are able to heat up the object very quickly.

Main Components

Available on Amazon

There is an induction heating module available on Amazon that is typically under $15 dollars. While it is possible to make your own, that is well beyond the scope of this article. This induction heating module is rated for between 5 and 12 volts. I included the written safety instructions that the manufacturer provides at the bottom of this article. The module comes with a coil that must be soldered to the device.

Available on Amazon

You need a power supply that can provide at least a few amps of current and a voltage between 5 and 12 volts. The power supply that I have is linked above gets you the max power for this device, which is 12V and 10 A. According the the manufacturer, the device is not rated for anything higher.

I used to use a variable voltage power supply before I got this nice power supply. If you have a variable voltage power supply, you can use it, but MAKE SURE YOU DO NOT SET IT ABOVE 12 VOLTS FOR THIS MODULE.

Available on Amazon

This socket adaptor connects directly to the power supply so you do not have to worry about loose connections.

Alternatively, you could use Alligator Clips and 18 Gauge Wire. The alligator clips require less work, but are less secure. I have used both, but I really like having a female connector that is secured snugly.

Tools/Materials for Assembly

Soldering Iron/Solder

You will need a soldering iron to solder the coil to the module. You can theoretically use the screw terminals instead, but the manufacturer warns that the plastic terminals can melt. As a result, I chose to solder the coil leads directly.

Drill/Drill-bits

You need to make a hole that the female jack connector can be pressed into. A 3/8th inch drill bit works well.

Wood/Wood Glue

This is optional, but I recommend making a small base like I did in my video so that you can move your induction heating device around without touching it directly.

Super Glue (or Tape)

You need something to secure the induction heater to you wood base.

Instructions

Disclaimer: Improper use of equipment or failure to comply with proper safety protocols can result in harm to the user. Please use caution when working with electricity. Do not attempt if you do not have an understanding of basic electrical circuitry and these components. Attempt at your own risk.

1. Remove the induction heating coil from its packaging. (Optional: bend the coil to a new desired shape and orientation if you want to change it. FYI: the shape of the coil affects its performance, so be careful.)
2. Solder the coil ends to the induction heating module.

Figure 3. An example of one coil end soldered to the module.

3. Create your base (wood structure) and attach your induction heating coil.

4. Take the red (+) and black (-) wires from the female jack connector and screw them into the backside screw terminals. Since the wire is in many strands, consider adding solder to the ends before screwing it down.

Figure 4. Properly secured wires.

5. Drill a 3/8th inch hole in the middle of the top wood piece. See the image below if you are confused.

6. Press-fit the female jack connector. Make sure it does not come out easily.

7. Plug in the DC Power Supply and connect the power jack to the female connector. A blue led light on the induction heater will light up to indicate the circuit is working. (FYI: the power supply takes about a second to turn on once it is plugged in)

Figure 5. Final Configuration

Additional Notes:

• If your power supply is only capable of drawing a few amps, the device may not have enough power to handle a large metal object. In addition, if you stick the metal object in too quickly, this also may be too large of a load for the power supply. When this happened to me (when I was using a different power supply than that listed above), you will notice that the LED on the induction heating module turns off.
• While the coil itself does not need to be hot in order to heat up the objects placed inside, the coil can start to get hot after prolonged use. Always treat the coil as if it is hot when you are using the device. The manual warns not to use for more than 5 minutes without allowing it to cool off.

Manufacturer’s Product Description and Notes

“Specification：
Input Voltage：DC 5V~12V
Max Power：120W
PCB Size：55 x 37 x 1.6 mm

Note:
1. When inductive heating, usually work for 5 minutes to power off cooling. Because the current is relatively large during induction heating, the coil heat is also relatively large. When heating, part of the heat generated by the heated object is transmitted to the heating coil. For a long time, the temperature of the heating coil is high. If the heating coil is connected to the terminal, the plastic part of the terminal will be melted. Therefore, when induction heating, it is best to solder the heating coil directly to the PCB
2. Only some types of materials can be effectively induction heated — mostly magnetic materials such as steel. Materials such as brass, copper and aluminum will be very difficult to heat.
3. A large capacitor placed in parallel with the supply voltage can help reduce the voltage/current drop that prevents the unit from starting.
4. This module should not be operating when no load, otherwise it might burn out the circuit.
5. You can check whether the blue LED indicator light up to see if the power is supplied or the module can functionally work. When the indicator is dim, maybe the power supply is insufficient, should use a higher power supply. Just make sure the power supply is within DC 5–12V.
Remark: You can solder the heating coil on the board.”

Disclaimer: I make a small cut of all sales through affiliate links, at no extra charge to the purchaser.