Aftermarket toaster oven controller.

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Whether you are doing advanced engineering on a limited budget, or you just really like toast, ToastDuino is for you. ToastDuino is an aftermarket temperature controller for retrofitting your average toaster oven into a piece of extraordinary equipment.

ToastDuino design is based on the Arduino Pro Mini schematic, and also the KTA-259 thermocouple shield by Ocean Controls.


- eight K-type thermocouple inputs

- two 16 amp 250VAC relay outputs

- FTDI serial interface

- 0.25° C resolution

- many I/O features

- program with Arduino IDE

It is intended for semi-permanent programming just like the Arduino Pro mini. Once the firmware is loaded, the algorithm can be adjusted with the potentiometers.

I designed this PCB because I was tired of using my ghetto-rigged toaster oven to reflow boards. It was a dangerous process.

This circuit is really useful, so I did a good job on the PCBs. It could be used for reflow soldering, curing glue, furnace, autoclave, biological processes etc.

Please feel free to tag onto this project. Share how you used Toast Duino!


Schematic Open Source <3 Share Alike

Adobe Portable Document Format - 981.36 kB - 05/02/2016 at 02:34


  • One year later: My ToastDuino Toaster Reflow demo

    Dean Gouramanis02/22/2017 at 19:44 0 comments

  • Official Release

    Dean Gouramanis05/02/2016 at 02:43 0 comments

    Toastduino is ready for the world.

    Toastduino Version 1.1 is the third generation design. This version is compatible with both 3.3v and 5v FTDI programming adapters. It also features an external 5VDC port for powering from an external supply, or tapping into the on-board 5VDC converter for external accessories.

    Several I/O pins and an SPI port are pinned-out, so Toastduino is a very general purpose device for any project involving temperature control.

    Buy one on Tindie. Share your build on Hackaday.

    : )

  • Website is almost ready

    Dean Gouramanis02/01/2016 at 21:19 0 comments

    The schematic and other specs are live on the new Toastduino website.

  • Project Status - V0.1

    Dean Gouramanis01/11/2016 at 22:03 0 comments

    So I began coding my toaster....

    I keep grinning every time I look up from the keyboard and see a toaster oven plugged into my PC. HA.

    I ran into a few bugs.

    1) I routed pins 10 and 11 for a Green and Red LED. Turns out they will not work because the Arduino SPI library dedicates them for serial communication. They are not actually used in this case, but they can not be re purposed easily.

    Thankfully I was able to connect the LEDs to pins A3 and A4, and configure those pins for output.

    2) The program reads the thermocouple once every second in order to throttle the heating elements. Everything was working beautifully except every 30 samples or so, the MAX31855 would return an error code. After alot of pondering I realized it was because of EMF noise. The thermocouple wires run parallel to the AC power lines so apparently there was too much noise. Once i connected circuit ground to earth ground the Toaster worked perfecty.

    Aside from those minor hiccups i'm really happy with my new reflow toaster.

    Next my plan is to perfect the PCB, and kick-off the Version 1.0 Open Source project!

    I will be changing two things in the new version.

    1) I will pin-out a really easy to use SPI port. This way people can connect LCD screens and other accessories.

    2) I am upgrading the power supply to the PBK-3 which can supply 500mA rather than the previously insufficient 200mA. Plenty of extra amperage to power accessories.

  • System Check

    Dean Gouramanis01/08/2016 at 15:46 0 comments

    I did an initial system check and everything is working great.

    I added an FTDI port to the front panel, this way programming and debugging will be a pleasure.

    These heating elements are rated for 220V operation, but i have them wired here to 110V. This provides a soft, even heat source.

    Two thermocouples (top and bottom) provide precise temperature measurements, and #toastduino makes the magic happen.

    Next on to firmware and documentation.

    The Tesla of toasters!

  • Wired up

    Dean Gouramanis01/07/2016 at 17:45 0 comments

    All I had was white wire.

    My hands are itchy from the fiberglass, but it was worth it. This is built to last a lifetime.

  • Thermal Insulation Installed

    Dean Gouramanis01/06/2016 at 16:38 0 comments

    A few years ago I planned to build a small brazing furnace, but I ran out of money before I finished buying parts. So I had this really fancy silica insulation laying around.

    I also had some adhesive-backed aluminum tape. I took my time and did a really nice job insulating the inside of the toaster oven.

    I was careful to seal-in the fiberglass behind tape, in order to prevent the glass fibers from getting all over my bedroom (which is where I do most of my reflow soldering unfortunately)...

    Anyway it came out fantastic. Now on to wiring.

  • PCB assembeled

    Dean Gouramanis01/06/2016 at 16:17 0 comments


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Hacker404 wrote 09/18/2017 at 22:34 point

Looks good. We don't have this type of toaster in my country. We have the ones where bread slots into the top vertically.

A bit off-topic ... my favorite joke about an 8-bit toaster ...

It has 256 settings as below

Value: 0 , Off

Value: 1 , Re-heat

Values: 2 to 255, 254 different densities of smoke.

  Are you sure? yes | no

Alex wrote 01/06/2016 at 17:39 point

This looks nice. What is this part with the blue heat shrink around? And I would realy like to see the shematic of this. 

  Are you sure? yes | no

Dean Gouramanis wrote 01/06/2016 at 18:07 point

Hi @al1

The blue part is a the PBK-1-5 power supply module from CUI. It powers the MCU and Relays from AC mains. 

So all you need to do to install it in a toaster is hook up AC mains to the ToastDuino, and then the heating elements to the relays. No need for an external power supply, which really simplifies things in this heat-intensive environment. 
My schematic is a mess right now. 

I will polish off a schematic and BOM once everything is tested.

PS. That is not blue heat shrink. It is a hard epoxy coating. Very nice.

  Are you sure? yes | no

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