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What makes ControLeo2 the best reflow oven controller?
  • Four outputs
    Control convection fans and heater elements individually.
  • Better heat distribution
    Having control over individual heating elements allows you to keep heat away from sensitive components.
  • Hot-spot elimination
    Intelligent software manages element on-time, reducing hot and cold spots in the oven.
  • Better heat direction
    Intelligent software controls whether heat comes from the top or bottom, depending on the reflow phase
  • Better current management
    Elements are turned on and off independently eliminating the current spikes common in single-relay controllers
  • Ready-to-run
    No programming needed. Just configure the fans/elements your oven has and the reflow wizard will do the rest. No need to connect ControLeo2 to a computer or write any software!
  • Proven hardware
    ControLeo2 is based on the original ControLeo, which has been field tested for more than a year. ControLeo was based on the Arduino Leonardo - another proven design.
  • Open-source
    ControLeo2 is fully compatible with the Arduino programming environment, and runs Arduino Leonardo sketches. A library and 15 sample programs for ControLeo2 has been posted to GitHub.
  • Reflow Wizard
    Intelligent software makes it easy to get your oven up and running. Ensures consistent results, run after run.
  • Reflow feedback
    If you connect ControLeo2 to a computer you can track the reflow progress and get data to plot a reflow temperature graph.
  • Servo support
    Supports industry-standard servos, so the oven door is automatically opened at the end of the reflow cycle.
  • J-STD-020 compliance
    The Reflow Wizard is aware of the standards governing reflow ovens, and will auto-tune your oven so that it conforms to them.


Reflow Wizard software
ControLeo2 ships with the "Reflow Wizard" software installed. The software has 3 parts:
  1. Test the outputs - helps you verify that the heater elements and convection fan (if applicable) work.
  2. Oven setup - this part allows you to configure what each output controls. You also set the maximum reflow temperature here.
  3. Reflow - This is where the magic happens!
The Reflow Wizard starts off in "learning mode". It looks at the configured hardware and maximum temperature, then takes an educated guess at how to achieve the correct reflow profile. It takes a few test runs to tune the duty cycle settings for each phase of the reflow cycle. Once it conforms to the J-STD-020 reflow standard, it exits learning mode. From then on, you'll get consistent runs time after time. The Wizard will continuously monitor the runs and make tiny adjustments if necessary.

You can follow the Wizard's performance and commentary by connecting ControLeo2 to a computer using USB.

The firmware running on ControLeo2 can be easily updated, following these instructions.


Step-by-step build instructions

Complete step-by-step instructions for building your own reflow oven can be found here.


ControLeo2 Test and Setup menu


ControLeo2 in action


ControLeo2 is open
There is no need to program ControLeo2 at all, but if you're a software guru you can tinker to your heart's content. We've open-sourced all the software we've written for ControLeo2, including the Reflow Wizard. The software consists of a single Arduino library that controls all of ControLeo2's functions, as well as 15 sample programs. You can find everything on GitHub (https://github.com/engineertype/ControLeo2)

ControLeo2 uses the standard Arduino environment. The library should be installed into your Arduino environment using the instructions found here: http://arduino.cc/en/Guide/Libraries. The single ControLeo2 library gives you access to all of ControLeo2's functionality. Installing the library also installs all the sample code we've written for it.

In Arduino, select the board as "Arduino Leonardo". Your sketches can then be sent to ControLeo2 using its micro-USB port.


ControLeo2 is expandable
ControLeo2 provides both 5V and 3.3V (max 80mA) to power additional components. There are 4 pins available for digital I/O (D3 supports PWM).


ControLeo2 enclosure
ControLeo2 uses a quality off-the-shelf flame-retardant ABS plastic enclosure with a textured finish. The holes are CNC machined to perfectly fit ControLeo2. The result is a high quality, tight fitting case that looks very good. We are thrilled with this enclosure. Only the lid has holes; you'll need to make a hole to route your wires through the case.


ControLeo2 specifications and features
  • ATmega32u4 microcontroller with Arduino Leonardo boot loader
    • 32Kb Flash memory
    • 2.5Kb SRAM
    • 1Kb EEPROM
  • LCD display - 2 lines x 16 characters.
  • 4 relay outputs - relays are connected using screw terminals or the 6-pin relay header (4 outputs, +5V, GND). The outputs provide up to 220mA at 5V. The outputs support connections to solid-state relays (SSRs) or mechanical relays
  • Buzzer - 80db at 10cm
  • 2 momentary switches - for user input.
  • ABS plastic case - custom fit, flame-retardant (UL94-5VA)
  • MAX31855KASA thermocouple - capable of reading temperatures from -200°C to 1350°C using a k-type thermocouple.
  • Input voltage: 5V (USB or screw terminals) - For reliability and longevity, the screw terminals should be used to power ControLeo2. For solid-state relays, the 500mA provided by USB is sufficient to power ControLeo2 and the relays. For mechanical relays please use a 1000mA 5V power supply connected to the screw terminals.
  • Pre-loaded software - Reflow Wizard


You can buy ControLeo2 here.