1. http://www.instructables.com/id/Hack-a-Toaster-Oven-for-Reflow-Soldering/?ALLSTEPS
This is a very detailed project that basically gives us step-by-step of what to do for this project. In order to control the oven’s temperature, he created his own controller circuit implementing a ATmega32U4 micro-controller to monitor the oven’s temperature using thermocouple and AD595AQ, and then control the oven’s heating element using a solid state relay. Thus the temperature data are logging from the sensor and the micro-controller is communicated using the AVR programming language. The controller features USB logging/debugging, USB bootloading, a graphic LCD display and 3 buttons. All the source codes, schematics, circuit drawings are provided for free.
2. https://www.sparkfun.com/tutorials/60
In this project, the temperature data is also logged using the sensor, which is a type-K thermocouple. They used the 16F88 PIC micro-controller and communicated with it using the Windows VB program. The PC software is not available.
3. https://courses.cit.cornell.edu/ee476/FinalProjects/s2006/ki38/Webpage/index.html
In this project, they also used the temperature sensor, which is a thermistor, to collect the oven’s temperature. The micro-controller that they used is an Atmel MEGA32 chip, which they communicated and programmed using the STK 500 board. The PC software that they used is available.
4. http://zavax.wordpress.com/2013/04/16/convert-a-toaster-oven-into-a-pcb-reflow-oven/
In this project, they used a TPI GK11M thermocouple and a thermocouple conditioner IC MAX6675 from Digikey. MAX6675 is Cold-Junction-Compensated K-thermocouple-to-digital convertor that has micro-controller-friendly SPI interface. Their micro-controller is the PIC32-base RTM that runs at 80MHz and the data can be transferred in and out through its USB2.0 port with little programming required. The PC software is not available.
5. http://reprap.org/wiki/Toaster_Oven_Reflow_Technique
They used the K-type thermocouple to log the temperature data and the Arduino board as the micro-controller. The Arduino can be programmed and connected easily on the PC. The PC software is also provided.
6. http://hforsten.com/toaster-oven-reflow-controller.html
He used the ATmega8U2 micro-controller as it is the cheapest AVR with hardware USB support. He also used the MAX31855 as a thermocouple-to-digital convertor, instead of cheaper temperature sensor ICs. The micro-controller will read the temperature and output PWM signal for the solid state relay which can be used to accurately control the temperature of the oven. The schematics and PC software are available.
7. http://hobbybotics.com/projects/hobbybotics-reflow-controller-v8-03/
This past project is the most detailed and closest to what we want to achieve. He explained all the details and theories behind the project and provided basically everything that we need to know. The circuit makes use of a MAX6675 Thermocouple IC, a MAX3232 for programming and serial communication, a header FTDI Basic 5V USB breakout board, a 4×20 HD44780 Parallel LCD, a buzzer for audio feedback and a connection for a Adafruit DS1307 Real Time Clock. He built his own controller circuit around the PIC16F877A (or PIC16F887). All the documentations are provided, including the PC software.
8. http://danstrother.com/2011/01/15/reflow-oven-controller/
In this one he used the Type-K thermocouples model 9251T93 to measure the oven’s temperature. To interface the thermocouples to a micro-controller, he used two of Maxim’s MAX6675 chip, both are cold-junction-compensated thermocouple ADCs with an SPI bus interface. The AT90USB1286 micro-controller is used as they are pre-programmed with a USB bootloader and so no other development tools are required. Part of the source code is avaliable.
This is a very good review. Today we will focus on the software options and their links to the microcontroller. We can also discuss an outline for documenting this first design phase. A centrial piece will be the top level block diagram.
Some other questions that you can explore on Monday:
Is there room in the toaster oven for the controller circuitry?
If there is room, what are the pros and cons of a separate control box?
Is the toaster oven well insulated? If not, is there room to add a high temperature insulation?
Is there any good reason to leave either of the current manual controls, or should they be removed?