The Heart of an Induction Heater

Heart of an Induction Heater
Hello everyone! I started this morning out with a beautiful walk along the gulf coast for the American Heart Association. I wanted to share two things with you today, a couple photos from the event and one more thing (keep reading).
Gulf Coast Heart Walk American Heart Association American Heart Association Heart Walk American Heart Association

Generosity Begets Generosity

All the giving got me thinking, after all, you know what they say about giving. Generosity Begets Generosity. Generosity is a gift that keeps on giving—so many of the gifts we receive in life turn us into givers.
I wanted to show my appreciation to the Patrons who continue to believe in this project even when life slows its progress way more than I’d like! I was reminded today that I actually did not start this project for myself. I am not a blacksmith, I have no immediate need for an induction heater, but I am a creator. Each and every human has this incredible capacity to imagine and to change things. I wanted to bring a tool within the reach of others that remained out of reach for most. Not a wimpy, “doesn’t deliver on what the box said kind of tool”, but one of a caliber that is not matched in the consumer market at all today.

The Heart of an Induction Heater

I would like to offer the “heart of an induction heater” to all of my existing Patrons (as of today September 22, 2018).
U-I Core Set
E/I Core from two U/I cores
U-I Core Set
At about twice the size of a human heart and just about as difficult to source, the matching transformer is by far the most critical, specialized component of the induction heater. Coolant flows around its core in two directions keeping it cool as huge amounts of energy flow through it, making it possible to pump power from your wall outlet into your workpiece. Without it, the IH is just an inverter with some other not really all that exciting electronics. It would be akin to a truck without a transmission. You can’t just connect the crankshaft to the wheels and expect anything good!
I’m including two massive U & I core sets. The same ones that make up the large E/I matching transformer in the newest revision.
Material: 3C85
  • Single U-I core set AL: ~8400
  • Single U-I core set µe: ~2000
  • Single U-Core Dimensions: 93mm x 76mm x  30mm thick
  • Single I-Core Dimensions: 93mm x 28mm x 30mm thick
  • Overall Dimensions: U-I Set: 104mm x 93mm
  • Opening Dimensions: 47mm x 36mm
3C85 Material Technical Data:
  • Optimal frequency: < 200kHz
  • Permeability ui:           2000 +/- 20%
  • Induction at 100kHz, 250 A/m, Bs:   > 400mT
Heart of an Induction Heater

But Wait There’s More

Since driving your IGBT properly is a big deal and kind of important for the whole setup, I’m also including a new driver PCB with two Powerex VLA504-01 Hybrid IC Gate Drivers and two Powerex VLA106-15242 DC to DC Converters. Just those four components are about a $70 value alone if you buy them from Digi-Key. The remaining components on the board are just a few dollars worth of passives. The full schematics and bill of materials for the Hybrid Driver board can be found here: https://github.com/ThingEngineer/ReactorForge/blob/master/hardware/Hybrid%20Driver/BOM.txt
Recap, what I’m giving my Patrons:
  • 2 x 93mm x 76mm x  30mm 3C85 Ferrite U Cores
  • 2 x 93mm x 28mm x 30mm 3C85 Ferrite I Cores
  • 2 x Powerex VLA504-01 Hybrid IC Gate Drivers
  • 2 x Powerex VLA106-15242 DC to DC Converters
  • 1 x New Hybrid Driver PCB

Send Me Free Stuff!

If you are currently a Patron as of the date of this post and would like me to send you this thank you gift, just send me a private message on Patron saying hello and include your shipping address. The only thing I would ask is that you only request this gift if you are going to use it. We’ll go on the honor system here.
I look forward to working on this project more and hearing your and feedback as well, as you either work on your own or use an IH I’ve built for you in the future.
Thank you!!!
Q: Is it possible to drive a tank circuit in an Induction Heater with one IGBT?
A: Yes.  This is actually how my brothers old IH is set up now. Here is a quick schematic. The capacitors were all off eBay for cheap.
Single IGBT Inverter
Matching transformer and coupling caps
Single IGBT Inverter
Filter Cap & Coupling Caps
Single IGBT Inverter
Single IGBT driver and brick
Single IGBT Inverter Schematic
Single IGBT inverter schematic
Q: Can you share more details on the matching transformer?
A: Of course but I need some more space to do it properly. I’m working on a post about just that. In the meantime here is a photo and a short explanation to give you something to start with.
  • The Matching transformer is wound with 1/4″OD inch copper tubing.
  • All windings are wrapped in x2 overlapping Scotch Professional Grade Vinyl Electrical Tape Super 88. Meaning as you spiral down the length of the copper tube the electrical tape covers 50% of the layer before it resulting in a 50%+50% overlap (no gaps) and a 200% layer thickness overall (better electrical and mechanical isolation).
  • The primary winding (connected to the inverter) is composed of 13-14 turns. It has terminals made of copper soldered near the ends to accommodate a high current connection while leaving the ends of the tube free to hook up to the cooling system.
  • The secondary winding (connected to the tank cap and work coil) is a single turn composed of 4 individual 1/4″ copper tubes connected on each end with a 1/2″ manifold. One side of the manifold connects to one side of the tank capacitor, the other connects to one side of the work coil via a copper plate. The other side of the work coil connects back to the other side of the tank capacitor via another copper plate in close proximity to the first plate. This whole set up ensure the flux is fully enclosed in the system. Were it not you would heat up surrounding metal and loose usable power. (An issue in the first model with the toroidal matching transformer and large tank setup.)
Matching Transformer
Q: If I’m not a Patron could I just purchase one or some of these items from you?
A: I’m not set up to do this formally yet but I can accept Paypal and work something out. I’m also still working on a bulk order for the passives to get the entire driver kit complete. The price difference with and without the passives will likely be less than a couple bucks, keep that in mind if ordering those parts would be an issue for you.
Q: What about the other parts of the system like the main board, AC rectification & filtering, liquid cooling setup, etc. Can I get one of those?
A: Although I do have fairly complete designs worked out on the rest of the system I don’t have a stock on the parts. I am going to start making posts on the individual components starting with the matching transformer to give you what you need to duplicate each part. The main board schematic and board design are on GitHub although I will be making some changes to it on the next go around.

Happy March!

Jeremiah's Knives
Good morning and can you believe it’s March already? Wow! Now that Chinese New Year is past the last of the packaging materials for the IGBT Hybrid Driver kits have shipped. I’m now looking forward to getting it all packaged up. I have some fun and unique ideas for the packaging as well. 🙂
Between ice and snow days, three kids with the flu, then me with it for a couple of days and throw some travel in there I’ve been working on the guide for the kit a bit more. It is coming together beautifully, and I enjoy working on it. But to be honest, I’m most excited to get back to work on finishing the main code. However since the drivers are a crucial part of the overall kit, this is time well spent.

Forging Ahead

On another note, while my brother Daniel is in the process of moving I let a friend, Jeremiah borrow the original induction heater. Jeremiah has been making knives for the better part of last year using stock blanks and handcrafting the handles from various materials. He wanted to get his feet wet forging his own blades from scratch but doesn’t have the area or set up for a flame forge. Maybe we’ll get some nice pictures or even a video or three. He is new to forging but has been studying the last few months, so he was ready for the IH!
Here is some of Jeremiah’s recent work. I believe he said these were Christmas presents this past year. 
 Jeremiah's Knives
I’ve met others with impressive talents in blade crafting like Larry Fahnoe, check out his creations too! I am truly excited to see more people with access to induction heating and what they’ll do with it.

Bluetooth Telemetry Link

Bluetooth Telemetry

This Bluetooth serial link is nothing new. I had it working on the existing setup to send data from the ReactorForge control board to the Processing visualization program. The HC-06 Bluetooth module enabled me to see the live telemetry coming from the ReactorForge. That helps you to understand what is going on and tweak parameters such as the PID settings.

Consolidation of Development Process

I’m excited to get the entire development process in one operating system. Before, I was bouncing between macOS, Windows in VMWare Fusion on the Mac, and a separate Windows machine. It’s a long story, but this was partly due to the Windows-only compiler I used at the time. Other shortcuts I made early in the process just to get things working enough to get the induction heater to Daniel’s shop also helped put me in that spot.

Problems Connecting to the HC-06 Bluetooth Module on Mac

Getting the HC-06 Bluetooth to Serial module working on macOS wasn’t hard, but I did have one issue. The HC-06 seemed to just disconnect randomly after a minute or two of being connected. Then when I would try to reconnect to it, the port would be busy. I knew it wasn’t busy or open using lsof | grep HC-06 or whatever your’s is named, Reactor-Link in my case.

I fired up Windows in VMware Fusion and paired the HC-06 Bluetooth module. Then I opened a connection to it using a terminal program. I also began a screen session (terminal) on the Mac side with a USB to serial adapter. The USB serial adapter was connected to the HC-06 Bluetooth module to monitor it (and send data from it).

Anyway, this worked fine, and the HC-06 Bluetooth module never lost connection on the Windows side. I did notice that on the Windows side, the HC-06 Bluetooth module asked me for asked me for the pin number during the pairing process, but it did not ask on the Mac side. I removed the device from on the Mac side in the Bluetooth manager and re-Paired it. To my annoyance and relief, this fixed the disconnecting issue. Maybe I changed the pin in the past since the last time it had been connected to the Mac.

Bluetooth on macOS

So this is the simple test setup. The photos say it all I think.

Bluetooth Telemetry

Bluetooth Telemetry

Bluetooth HC-06.pdf

Libraries, Drivers, Etc.

With that working, I’m going to work on the libraries now. I’m looking at whether or not to get the existing libraries working in the new environment or use new libraries.  I’m leaning toward new libraries because there are quite a few compiler warnings and even some errors from the old ones. I’ll have to update function names and setup code, but I’d prefer to start with something cleaner and updated. I’m pushing it all to GitHub as I go!

Addition Terminal Jargon

The astute reader might notice that I am using the /dev/tty.* version of the device rather than the /dev/cu.* version. So, what’s the difference? TTY devices are for calling into UNIX systems, whereas CU (Call-Up) devices are for calling out from them (e.g., modems). We want to call-out, so /dev/cu.* is the correct device to use.

The technical difference is that /dev/tty.* devices will wait (or listen) for DCD (data-carrier-detect) e.g., someone calling in, before responding. /dev/cu.* devices do not assert DCD, so they will always connect (respond or succeed) immediately. Since neither the HC-06 Bluetooth module or the USB to serial adapter support DCD it’s not an issue. Still, following best practice, you should use the correct port.

So why did I use the wrong one in the photos? I switched to /dev/tty.* when I was having the connection issue and just forgot to switch back before documenting it.

Development Environment

Development Environment

If you follow the GitHub repository https://github.com/ThingEngineer/ReactorForge by clicking [Watch] you may have noticed work on the firmware. I’ve begun setting up the new development environment. Going forward, I don’t want to deal with switching to Windows to work in AVR Studio. I never liked that environment anyway. I had talked about possibly moving everything into the Arduino environment because of its popularity, however that has its own set of issues. For starters, support for the AT90PWM family of chips isn’t there, and I don’t want to spend the time to add it. Then there’s this:

https://atom.io + https://atom.io/packages/platomformio = frickin awesome

Beginning Development Environment

Arduino is a great prototyping platform and IDE to get started on if you have never worked with microcontrollers. As a beginner, it can get you building projects faster than any other platform out there. But eventually, the features that make it convenient and easy to use can hold you back. It lacks many features which make writing code quicker, easier, and have become quite standard in modern text editors. There are also bits of code that get inserted into your code that can cause some very head-scratching issues.

Moving Beyond Arduino

The next logical step is to leave the Arduino IDE behind. We do that by working in a more fully-featured development environment. Atom + PlatformIO is my new favorite open source cross-platform IDE. It even comes with the Arduino framework among others. That lets you test drive it with a code structure you are familiar. When you are ready, you can remove the training wheels and go full native C++. There is so much more I could brag about with both of these tools. But I’ll let you discover the awesomeness yourself!

Development Environment

Next Steps

What’s next? I’m going to begin porting over the libraries used in the existing project. Then the main code, and start rewriting, optimizing, etc. The photo above is a test rig I used for setting up the new IDE. I will continue to use it throughout the porting process. Once the code is stable in its new environment, I’ll switch over to the ReactorForge!

I had also planned on using this setup to demo and explain the basics behind the AT90PMW software PLL setup. I’ll get to that but for now, it’s back to work in the new development environment!

Patreon Charges and 260 Pound Parts Delivery for IH Kit

Patreon Charges

There has been a lot of confusion created by they way Patreon charges its patrons and paying creators. You can find the official information can here: https://patreon.zendesk.com/hc/en-us/articles/115005631963 And here is another excellent article on the topic by TechCrunch.

TLDR; The short version is, Patreon moved its credit card processing service fees from the creator to the patron. Because of this change, Patreon was able to lower the overall fee amount and give more to the creator. The fee amount is (2.9% + $0.35) for each monthly pledge.

Because I have worked on unique e-commerce projects, I understand the intricacies and complications of bulk credit card processing, multiple payees, and the associated charges and chargeback liabilities. However, I do not support Patreon’s decision, and I firmly believe there is a better solution. Because Patreon is a goodwill engine, I think this move is, for lack of better terms, just weird. In addition, I won’t personally be canceling any of my Patreon pledges. Nevertheless, as a patron myself and now a fledgling creator, I do hope that we see these processing fees moved back to the creator.

Other Support Options

Your support is much appreciated, but entirely voluntary. You may continue to make a small donation to support the project and website using Patreon. If you decide to cancel out of principal, I understand entirely. If you prefer I’ve added a PayPal button on the pledge page “Coffee” to enable you to make a small reoccurring monthly pledge that you can change or cancel it at any time.


Support the ReactorForge via PayPal



Or you can send a one-time pledge. Please include a note to let me know it’s a gift and what made you decide to support ReactorForge!




I may add members only functionality to the website linked to Patreon PayPal as well, to mirror and even enhance the capabilities Patreon offers. But I’m not sure there is indeed a need for that yet, or possibly ever. Thank you all again for your support, be it monetary, intellectual, or constructive criticism. I value all of it!

ReactorForge Parts Delivery

I just received the first shipment of parts for building more ReactorForge induction heaters, 258 pounds worth. This component is of one particular importance and one I have settled on despite other possible changes I will be making to the design. Anyone care to take a guess what part this is?

ReactorForge Induction Heater Parts Shipment ReactorForge Induction Heater Parts Shipment

Mains Power Feed Complete

Mains Power

This is the last mains power update for the ReactorForge Induction Heater. It will be the last because it’s complete! Here is how the last couple days of that process went.

Mains Power

I started by connecting the jumpers from the custom splice connector to the 60 Amp 240-volt dual pole breaker and ground bus. The photo shows green hooked to the neutral bus. I later moved this as I did not need to tap 120-volt like I thought I would have to since the ATX power supply runs on 240-volt now. (I just forgot, it’s been a while.)

Mains Power

And here is the 240-volt quick disconnect assembly installed and ready. I will print another version of the slide lock. The slides should be solid so the splice connectors are not accessible while the wires are disconnected.

Mains Power

Next, I prepared the 2 AWG mains power feeder lines. These will connect the splice block directly to the input of the ReactorForge.

Mains PowerMains Power

The splice block side has thick metal tabs that are double layered with heat-shrink tubing. These provide a high current, high durability connection to the screw terminal that will stand up to multiple connect/disconnect cycles.

Mains Power

The Induction Heater side has heavy duty lugs that will accept the terminal post. These are also insulated with double layers heat-shrink.

Mains Power

Bringing It All Together

And here you can see the feeder lines connected to the input of terminal posts on the back of the ReactorForge. I also ran a USB extension with a small hub for connecting the Atmel ISP programmer. I put the Bluetooth dongle here as well. It communicates with the mainboard to send/receive commands and system telemetry.

Mains PowerMains Power

I then installed a variac between the mains contactor and the inverter input filter.

Mains Power Variac

When software activates the contactor, 240 volts directly feeds the inverter typically. Since I have a decent amount of testing to do, I severed that connection and installed the variac to allow lower power testing.

Mains Power

I taped up the small areas where 240 volts was accessible in the front to avoid accidental contact or tools shorting things out. Getting my fingers across 240-volt mains power is not something I want to experience twice!

Mains Power VariacMains Power

On To The CODE!

That’s it for cooling and mains power connections. The next step is to get the programming environment set back up. I will turn things up as is and do some testing to make sure everything is still good. Once that is done I will get right to the next big task, I’ve decided to port the entire thing to Arduino. This won’t be too difficult since the code is already in C and I will be glad to get away from AVR Studio, to be honest. I made the choice to move to Arduino due to is massive use and rise in popularity over the last few years. Since this is an open source project I want to use a platform that people are familiar with. Let’s put industrial level induction heaters right up there with open source 3D printer firmware!

PSA – Net Neutrality – README

Net Neutrality

Don’t silence humanities most successful form of communication!

Despite what country you live in the topic of Net Neutrality once again affects you. I will get back to updates and work on the ReactorForge Induction Heater tonight, but this is a pressing issue, and we should all be very concerned. More so than concerned we should be active and involved. Voicing your opinion requires only minimal effort. If you don’t have an opinion or have never even heard of the issue, don’t just repeat someone else’s. A quick google search of “Net Neutrality 2017” will help explain the problem. Yes, do include 2017, because this happened already, back in 2015. The following paragraph is my synopsis and view on the matter.

Net Neutrality 2017

I rarely voice my opinion publicly on political matters but hear me out. Our policymakers disgust me. Despite the fact that both parties support net neutrality, they yet again go against our voice. The internet is by far, the most successful form of communication humans have ever invented. We can not give away control of that medium to entities who would redefine it for their financial gain. ISPs or any corporate entity for that matter SHOULD NOT be in control of Internet services. Internet traffic should be treated equally – email, files, web content, can’t be blocked, slowed or discarded by ISPs. I hope our state reps continue to back us up. Call, Facebook, Twitter, and or snail mail your rep! https://www.house.gov/representatives/find-your-representative

ReactorForge History – A brief history lesson 01010010

ReactorForge History

There were many before it, after it and in-betweens, but these are the milestones! This is a brief ReactorForge History lesson.

ReactorForge History

From left to right.

  • The first MOSFET version on a PCB. It worked great but didn’t couldn’t handle the power level I wanted. I ended up pushing it to failure and moving to brick IGBTs.
  • The first IGBT version on a PCB. This design is based on a CD4046 PLL and uses gate drive transformer to drive the large brick IGBTs (the ReactorForge now uses hybrid drivers). If you are into electronics and you’ve never worked with a PLL, even if just on a breadboard you should. PLL’s are very well documented, fascinating little devices. This circuit works great but its frequency operation range was limited by the external passives for the VCO (voltage controlled oscillator). Due to its reliance on these passive components, it is also affected by temperature.
  • For mainly that and a few other reasons I decided to explore a software PLL solution. After going around the usual suspects and understanding how a PLL worked I thought there must be some way to do it with a low-cost MCU, not a freaking FPGA or high power processor. Maybe some type of PWM/comparator combination I thought. I found my solution in a motor controller, or power stage controller chip made by Atmel, the PSC216,316 microcontroller. That’s what this breadboard is, the early testing for what is now a rock-solid way to find the resonant frequency (Fr) and adjust power levels by offsetting that frequency from the current Fr all while soft switching (i.e. not making heat in the wrong places and exploding electronics). This was the result of those early tests…

ReactorForge History - Current

The Future:

One more board redesign may be in order but we’ll see. I may look into reducing the size of the board down the standard Eurocard PCB size of 100mm x 160mm. Although the current size is still within the free size limit of 160mm^2 for Autodesk Eagle.

That was the ReactorForge History, now let’s forge ahead to the future!

Cooling is a GO

Cooling - connected and flushed

I got the new fittings and hoses hooked up then flushed the water chiller and the induction heater. No leaks, cooling is a go!

Cooling - connected and flushed

Cooling - New metal base for cart

Before putting it back on the cart I replaced the top plastic liner with 16 gauge sheet metal that I cleaned and lightly wiped down with oil. I think I’ll go back and add a lip around 3 sides with the box break to catch any falling sparks and molten beads of metal that try to escape.

Back on the cart!

Cooling setup on cart

And here it is with cooling set up on the new cart.

Cooling setup on cart

Now to move on to power. I am making a quick disconnect near the breaker box. I will need to draw and 3D print a small enclosure for the 3/8″ dual splicers. More on that progress here.

Hooking up cooling water and power

Hooking up cooling water - parts laid out

Hooking up cooling water, but first, fittings!

Hooking up cooling water - fittings

One trip the hardware store later and I’m ready to hook utilities up to the induction heater. 

Hooking up cooling water - parts laid out

Hooking up cooling water isn’t the only step… Power!

I also ordered a larger variac, a 5000VA 220V model to aid in testing and firmware optimization. I have a small 2000VA 120V variac but running it on such low voltage skewed a lot of the readings. The variac is nice because running full power while testing new features can a bit nerve-racking and wasteful.