aurelius:
I'm looking to create a solder reflow oven similar to the one created on the Ben Heck show. I want to take the AT MEGA chip and put it on it's own circuit board. I know I'll need a crystal, but I'm not sure what else is needed exactly. What do I need to take 120v off the power supply cable to the toaster oven and get it to 5V DC for the arduino? I know I could pull apart a wall wart, but that seems a bit messy. Perhaps that is the best option though. Thought I would get everyone's take on that before starting.
May I suggest a different tack than going with the Sparkfun controller? For one, no control code is provided. Secondly, it runs on a PIC microprocessor. Third, the folk at Sparkfun have so much confidence re: the American legal system that the unit is only sold as kit.
My suggestion would be to wait for the folk at Rocketscream to make their Atmel-based controller available again. It may take a while to arrive, but the ease of use is great because they use the Arduino IDE to program the thing. I had my first experience with forking a open-source project when I modestly upgraded the code to include a switch between leaded and lead-free solder profiles, giving a abort message when the initial temperature is too high, and making use of the fan relay option.
So what I think makes this unit great is the hardware is based on the Arduino form factor (it's a shield that you can use with the Uno and similarly-sized units), it's fully assembled, it has two built-in switches, it uses a K-thermocouple (easy to source) and it leverages the great work by the Adafuit team (thermocouple support) as well as Brett Beauregards PID library. Simpletons like me can then easily make small improvements as described above.
Rather than follow in my footsteps as far as ripping out the existing control hardware and installing a Crydom D2425D SSR inside the toaster oven, a better option may be to buy a fully-assembled PowerSwitch Tail and ignore the fan setting. Should take a lot less time and less dangerous to those new to the business of line-voltage electronics. One thing you will likely have to do though is to insulate the inside of the oven cavity to allow heating rates that are compatible with the solder profiles published by manufacturers.
For those that also want to install the SSR on the inside, go over the circuit before ordering one. My circuit included a fat diode to reduce the duty cycle to 50%. If your circuit also has a similar diode, use a SCR-based SSR, not a Triac. On the other hand, if no diode is present, a Triac-based SSR will give you more output. As it were, the SCR-based toaster is running at 1300W when input is 100% and the heat sink on the back of the SSR is more than a good idea. I simply sandwiched the exterior casing of the toaster oven between the SSR and the heat sink, works great.
One other tip is the use of the great pre-crimped wires that Pololu sells, along with a plastic housing that the crimped connections click into. Makes for a very clean install, especially if you heat-shrink the wire harness after making the connector.