Hi guys,
tl;dr: Im trying to reinvent the solder reflow oven using LM35 and PID Controller as a training exercise.
I would definitely love some feedback and guidance for a project I have in mind...
The project that I planing to do is to implement a PID Controller on an old toaster oven that I have laying around the house. I saw many tutorial on the web on how to implement the project to become a solder reflow oven and most of them also share an excellent sketch too... However being the hacker that I am, I would like have this project ( at the very least the PID controller part ) from the ground up. I am an electric/electronic student that learn control theory however I'm amaze that how different the theory is compared to the real life application. Therefore I would like to used this project as my introduction to real life application of PID controller. Well I guess thats enough as my back ground story.
For the hardware part of this project I guess I got that covered. I'll be using a relatively cheap temperature sensor the LM35. The Arduino will control a Solid State Relay that will be the switch that turn on/off the heating element of the Oven and because i wanted this project to be a stand alone project, for the user interface I would be using the humble 2x16 LCD Screen and 4 switch representing select, enter, up and down.
Below I have attach a ( sorry for using Fritzing ) general overview of my connection. A simple mechanical relay is used to represent the Solid State Relay but other than that I guess that all?
I had played around with LM35, LCD, relay control and also Switch Debounce and Change State beside then Switch short and long press too. So in essence it look like not really a big task but as always the devil is in the detail. I hope I could use this forum to record and communicate with the member of this forum for guidance thus making this project as open source as possible.
For those that are wondering why use LM35 as its range can only go ( in some model) from 0oC to 100oC. Well although its not hard to find a K type thermocouple and its amplifier, cost wise its kinda restrictive. I have time to spend but not money though therefore i would love to use part I have on hand. On the bright side, I may used this oven from 60oC to 80oC only, this is located nicely in LM35 temperature range.
On the programming side of things, I have a relatively vague idea of what the end result would be but would love to have some feedback too.
So far I based on my previous search, I saw that there is a PID library written by Brett and his amazing tutorial had help me a lot on understanding how PID work in real life application. The example in the library are amazing and the library help guide me a lot. Many have used his library in so much success but hey I'm trying to reinvent the wheel if I could say so myself all in the name of learning and experience.
If anyone could give me a feedback about this project are very much welcome. If anyone could share their experience and potential down fall or flaws in my logic are welcome too.
